MIC33M350

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Document overview

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• PDF pages: 32

Technical content

Features

• 2.4V to 5.5V Input Voltage Range
• 3A Output Current
• Pin Strapping Voltage Selection: - Three-state pins (nine voltage combinations) or 3.3V output voltage
• Passes Automotive AEC-Q104 Reliability Testing
• Reduced Component Count (no feedback resistors)
• High Efficiency (up to 95%)
• Output Discharge when Disabled
• Constant On-Time Control with High Switching Frequency: - 1.2 MHz typical at 1.0V output voltage
• ±1.5% Output Voltage Accuracy Over Line/Load/Temperature Range
• 0.8 ms/V Soft Start Speed
• Supports Safe Start-up with Pre-Biased Output
• Typical 1.5 µA Shutdown Supply Current
• Low Dropout Operation (100% duty cycle)
• Ultra Fast Transient Response
• Latch-Off Thermal Shutdown Protection
• Latch-Off Current Limit Protection
• Power Good (PG) Open-Drain Output
• Meets CISPR32 Class B Radiated EMI
• Meets CISPR 25 Class 5 Radiated EMI
• Package: 3.0 mm × 4.5 mm × 1.8 mm, 24-Lead QFN

Applications

• Solid State Drives (SSD)
• Tablets, Netbooks and Ultrabooks
• FPGAs, DSP and Low-Voltage ASIC Power General Description The MIC33M350 device is a pin-selectable output voltage, high-efficiency, low-voltage input, 3A current, synchronous step-down regulator power module with integrated inductor. The Constant On-Time (COT) control architecture with HyperLight Load provides very high efficiency at light loads, while maintaining an ultra-fast transient response. The MIC33M350 output voltage is set by two V SEL (Voltage Selection) pins, between nine different values. This method eliminates the need for an external feedback resistor divider and improves the output voltage setting accuracy. The 2.4V to 5.5V input vo ltage range, low shutdown and quiescent currents make the MIC33M350 device ideal for single cell Li-Ion battery-powered applications. The 100% duty cycle capability provides Low Dropout operation, extending oper ating range in portable systems. The MIC33M350 pinout is compatible with the MIC33M356 I 2C-based programmable regulator version, such that applications can be easily converted. An open-drain Power Good output is provided to indicate when the output voltage is within 9% of regulation and facilitates the interface with an MCU. If set in shutdown (EN = GND), the MIC33M350 typically draws 1.5 µA, while the output is discharged through 10pull-down. MIC33M350 is available in a thermally efficient package: 24-Lead 3.0 mm x 4.5 mm x 1.8 mm QFN package, with an operating junction temperature range from -40°C to +125°C. MIC33M350 passes Automotive AEC-Q104 Reliability Testing. FIGURE 1: Radiated Emissions, CISPR32, Class B (VIN = 5V, VOUT = 1V, IOUT =3 A ) . Vertical Polarization Horizontal Polarization 3A, Pin Strapping Power Module with HyperLight Load® Mode and Output Voltage Select

 2020-2021 Microchip Technology Inc. DS20006348B-page 3 MIC33M350 Functional Block Diagram 0.47 µH VOUT/3A 0.6V 0.8V 0.9V 1.0V 1.2V 1.5V 1.8V 2.5V 3.3V VIN 2.4V to 5.5V MIC33M350 EN SW PGND SVIN Control Logic TON ADJUST PVIN MINIMUM TOFF PG 100k VIN PG HSD LSD VSEL1/VSEL2 DECODE LOGIC VSEL1 VREF DAC ZC VSEL1 VSEL2 RIPPLE INJECTION COMP VREF -9% DELAY 165°C/143°C OT AGND 2.225V/ 2.072V UVLO PD 10Ω 1 µF VREF PD EA 22µF µF 0.1 µF

DS20006348B-page 4  2020-2021 Microchip Technology Inc. NOTES:

 2020-2021 Microchip Technology Inc. DS20006348B-page 5 MIC33M350

1.0 ELECTRICAL CHARACTERISTICS

Absolute Maximum Ratings† ESD Rating(1) Note 1: Devices are ESD-sensitive. Handling precautions recommended. Human body model, 1.5 k in series with 100 pF. Operating Ratings(1) Note 1: The device is not ensured to function outside the operating range. † Notice: Stresses above those listed under “Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at those or any other conditions above those indicated in the operational sections of this specification is not intended. Exposure to maximum rating conditions for extended peri- ods may affect device reliability.

DS20006348B-page 6  2020-2021 Microchip Technology Inc. ELECTRICAL CHARACTERISTICS (1) Electrical Specifications: Unless otherwise specified, PVIN =5 V ; VOUT = 1.0V, COUT = 47 µF, TA = +25°C. Boldface values indicate -40°C  TJ  +125°C. Parameter Symbol Min. Typ. Max. Units Test Conditions VIN Supply Input Range PV IN 2.4 — 5.5 V Undervoltage Lockout Threshold UVLO 2.15 2.225 2.35 VS V IN rising Undervoltage Lockout Hysteresis UVLO_H — 153 — V SV IN falling (Note 3) Operating Supply Current I IN0 —6 0 100 µA V FB =1.2V, non-switching Shutdown Current I SHDN —1 . 5 10 µA V EN = 0V, PVIN = SVIN = 5.5V, 20 µA V EN = 0V, PVIN = SVIN = 5.5V, Output Voltage Output Accuracy V OUT_ACC 0.5910 0.6 0.6090 VV SEL2 = 0; VSEL1 = 0 0.7880 0.8 0.8120 VV SEL2 = 0; VSEL1 = Z 0.8865 0.9 0.9135 VV SEL2 = 0; VSEL1 = 1 0.9850 1 1.0150 VV SEL2 = Z; VSEL1 = 0 1.1820 1.2 1.2180 VV SEL2 = Z; VSEL1 = Z 1.4775 1.5 1.5225 VV SEL2 = Z; VSEL1 = 1 1.7730 1.8 1.8270 VV SEL2 = 1; VSEL1 = 0 2.4625 2.5 2.5375 VV SEL2 = 1; VSEL1 = Z 3.2505 3.3 3.3495 VV SEL2 = 1; VSEL1 = 1 Line Regulation — 0.03 — %V OUT = 1.0V, VIN = 2.5V to 5.5V, IOUT = 300 mA (Note 3) Load Regulation — 0.1 — %V OUT = 1.0V, IOUT = 0A to 3A (Note 3) Enable Control EN Logic Level High V EN_H 1.2 —V V EN rising, regulator enabled EN Logic Level Low V EN_L —— 0.4 VV EN falling, regulator shutdown EN Low Input Current I EN_L — 0.01 500 nA V EN = 0V EN High Input Current I EN_H — 0.01 500 nA V EN = 5.5V Enable Lockout Delay 0.15 0.25 0.4 ms VSEL Logic Level Control VSEL1,2 Logic Level High V SEL_H 1.2 — — V V SEL1,2 rising, regulator enabled VSEL1,2 Logic Level Low V SEL_L —0 . 4 V V SEL1,2 falling, regulator shutdown VSEL1,2 Logic Level Open V SEL_O —0 . 8 — V V SEL1,2 falling, regulator shutdown (Note 3) VSEL1,2 Low Input Current I VSEL_L -1 0.01 1 µA V SEL1,2 = 0V VSEL1,2 High Input Current I VSEL_H -1 0.01 1 µA V SEL1,2 = 5.5V Note 1: Specification for packaged product only. 2: Tested in open loop. The closed-loop current limit is affected by the inductance value. 3: Not production tested, data from bench characterization only

 2020-2021 Microchip Technology Inc. DS20006348B-page 7 MIC33M350 TON Control/Switching Frequency Switching ON Time T ON —1 8 0 — n s V IN = 5V, VOUT = 1V Switching Frequency FREQ —1 . 2 — MHz VOUT = 1.0V, IOUT = 3A (Note 3) —1 . 1 — V OUT = 3.3V, IOUT = 3A Maximum Duty Cycle DCMAX — — 100 % Note 3 Short Circuit Protection High-Side MOSFET Forward Current Limit ILIM_HS 45 6 . 5 A Note 2 Low-Side MOSFET Forward Current Limit ILIM_LS —4 . 2 — A Note 2, Note 3 Low-Side MOSFET Negative Current Limit ILIM_NEG -2 -3 -4 A Note 2 N-Channel Zero-Crossing Threshold IZC_TH —0 . 9 — A Note 3 Current Limit Pulses Before Hiccup HICCUP — 8 — Cycles Note 3 Hiccup Period Before Restart — — 1 — ms Note 3 Internal MOSFETs High-Side On Resistance R DS-ON-HS —3 06 0 m Ω ISW =1 A Low-Side On Resistance R DS-ON-LS —1 64 0 m Ω ISW =- 1 A Output Discharge Resistance R DS-ON-DSC —1 05 0 Ω VEN =0 V , VSW = 5.5V, from VOUT to PGND SW Leakage Current I LEAK_SW —1 10 µA P VIN = 5.5V, VSW = 0V, VEN =0 V , current flowing out of SW pin Power-Good (PG) Power Good Threshold PG_TH 87 91 95 %V OUT VOUT rising (good) Power Good Hysteresis PG_HYS — 4 — %V OUT VOUT falling (Note 3) Power Good Blanking Time PG_BLANK — 65 — µs Note 3 PG Output Leakage Current PG_LEAK — 30 300 nA V OUT =V OUT (NOM), VPG =5 . 5 V Power Good Sink Low Voltage PG_SINKV — — 200 mV V OUT = 0V; IPG =1 0m A Thermal Shutdown Thermal Shutdown T SHDN —1 6 5 — ° C T J rising (Note 3) Thermal Shutdown Hysteresis TSHDN_HYST —2 2 —° C T J falling (Note 3) Thermal Latch-Off Soft Start Cycles TH_LATCH — 4 — — Note 3 ELECTRICAL CHARACTERISTICS (1) (CONTINUED) Electrical Specifications: Unless otherwise specified, PVIN =5 V ; VOUT = 1.0V, COUT = 47 µF, TA = +25°C. Boldface values indicate -40°C  TJ  +125°C. Parameter Symbol Min. Typ. Max. Units Test Conditions Note 1: Specification for packaged product only. 2: Tested in open loop. The closed-loop current limit is affected by the inductance value. 3: Not production tested, data from bench characterization only

DS20006348B-page 8  2020-2021 Microchip Technology Inc. TEMPERATURE SPECIFICATIONS Electrical Specifications: unless otherwise specified, SVIN =P VIN =5 V ; VOUT = 1.0V, COUT =4 7µ F , TA =+ 2 5 ° C . Boldface values indicate -40°C  TJ  +125°C. Parameters Sym. Min. Typ. Max. Units Conditions Temperature Ranges Junction Temperature T J -40 — 125 °C Storage Temperature Range T A -65 — 150 °C Package Thermal Resistances Thermal Resistance, 24-Lead, 3 mm x 4.5 mm QFN

 2020-2021 Microchip Technology Inc. DS20006348B-page 9 MIC33M350

2.0 TYPICAL CHARACTERISTIC CURVES

Note: Unless otherwise indicated, PVIN =5 V , VOUT =1 V , COUT =4 7µ F , TA =+ 2 5 ° C . FIGURE 2-1: Operating Supply Current vs. Input Voltage, Switching. FIGURE 2-2: High-Side Current Limits vs. Temperature. FIGURE 2-3: Operating Supply Current vs. Temperature, Switching. FIGURE 2-4: RDS(on) vs. Temperature. FIGURE 2-5: Efficiency vs. Load Current (VOUT =0 . 6 V ) . FIGURE 2-6: Efficiency vs. Load Current (VOUT =1 V ) . Note: The graphs and tables provided following this note are a statistical summary based on a limited number of samples and are provided for informational purposes only. The performance characteristics listed herein are not tested or guaranteed. In some graphs or tables, the data presented may be outside the specified operating range (e.g., outside specified power supply range) and therefore outside the warranted range. 2SHUDWLQJ6XSSO\\&XUUHQW 9,1 9287 9 ,287 P$ +//PRGH 4.5 5.5 6.5 -40 -25 -10 5 20 35 50 65 80 95 110 125 High Side Current Limit (A) Ambient Temperature (°C) VIN = 5.0V VOUT = 3.3V VOUT = 1V 4.5 5.5 6.5 -40 -25 -10 5 20 35 50 65 80 95 110 125 High Side Current Limit (A) Ambient Temperature (°C) VIN = 5.0V VOUT = 3.3V VOUT = 1V 5'621 $PELHQW7HPSHUDWXUH +LJK6LGH215HVLVWDQFH /RZ6LGH215HVLVWDQFH (IILFLHQF\\ ,287 9,1 9 9,1 9 9,1 9 9287 9 (IILFLHQF\\ ,287 9287 9 9,1 9 9,1 9 9,1 9

 2020-2021 Microchip Technology Inc. DS20006348B-page 13 MIC33M350 Note: Unless otherwise indicated, PVIN = 5V, VOUT = 1V, COUT = 47 µF, TA = +25°C. FIGURE 2-25: Line Transient Response. VIN 2V/div PG 5V/div 1m s / d i v Step from 4.5V to 5.5V IOUT 2A/div VOUT 10 mV/div AC coupled

DS20006348B-page 14  2020-2021 Microchip Technology Inc. NOTES:

 2020-2021 Microchip Technology Inc. DS20006348B-page 15 MIC33M350

3.0 PIN DESCRIPTION

The descriptions of the pins are listed in Table 3-1. TABLE 3-1: PIN FUNCTION TABLE MIC33M350 Symbol Pin Function 1, 2, 3, 10, 11 P GND Power Ground Pin: PGND is the ground path for the MIC33M350 buck converter power stage. 4, 5, 6, 7, 8, 9 SW Switch Node Pin

17 PV IN Power Supply Voltage Pin

18 SV IN Analog Voltage Input Pin. The power to the internal reference and control sections of the MIC33M350 device. A 1.0 µF ceramic capacitor from SVIN to GND must be used. Internally connected to PVIN through a 10 resistor.

19 V SEL2 Output Voltage Selection Control Pin 2 (Input): The Logic state of the

VSEL1 and VSEL2 selects the register that sets the output voltage. This input has three Digital states: High, Low and Floating.

20 V SEL1 Output Voltage Selection Control Pin 1 (Input): The Logic state of the

VSEL1 and VSEL2 selects the register that sets the output voltage. This input has three Digital states: High, Low and Floating. 21 EN Enable Pin (Input): Logic high enables operation of the regulator. The EN pin should not be left open.

22 PG Power Good Pin (Output): This is an open-drain output that indicates

when the output voltage is lower than the 91% limit.

23 V OUT Output Voltage Sense Pin (Input): This pin is used to remote sense

the output voltage. Connect VOUT as close to the output capacitor as possible to sense output voltage. Also provides the path to discharge the output through an internal 10 resistor when disabled. 12, 13, 14, 15, 16 OUT Power Output Side Connection Pins

24 A GND Analog Ground: Internal signal ground for all low-power circuits

25 EP1_P GND Exposed Thermal Pad Pin: Internally connected to PGND

26 EP2_P GND Exposed Thermal Pad Pin: Internally connected to PGND

27 EP_SW Exposed Thermal Pad Pin: Internally connected to SW Node

28 EP_OUT Exposed Thermal Pad Pin: In ternally connected to Output side

DS20006348B-page 16  2020-2021 Microchip Technology Inc.

3.1 Power Ground Pin (P GND)

PGND is the ground path for the MIC33M350 buck converter power stage. The P GND pin connects to the sources of the low-side N-Channel MOSFETs, the negative terminals of input capacitors and the negative terminals of output capacitors. The loop for the Power Ground should be as small as possible and separate from the Analog Ground (A GND) loop.

3.2 Switch Node Pin (SW)

The SW pin connects directly to the switch node. The Switching Node output pin is connected to the internal MOSFETs and inductor. Due to the high-speed switching on this pin, the SW pin should be routed away from sensitive nodes. The SW pin also senses the current by monitoring the voltage across the low-side MOSFET during off-time.

3.3 Input Voltage Pin (PV IN)

This is an input supply to the source of the internal high-side P-channel MOSFET. The PV IN operating voltage range is from 2.4V to 5.5V. An input capacitor between PV IN and the Power Ground (P GND) pin is required and placed as close as possible to the IC.

3.4 Analog Voltage Input Pin (SV IN)

The power to the internal reference and control sections of the MIC33M350. A 1.0 µF ceramic capacitor from SV IN to ground must be used. Internally connected to PVIN through a 10 resistor.

3.5 Output Voltage Selection Control

Pin 2 (VSEL2) The Logic state of the V SEL1 and V SEL2 selects the output voltage. This input has three Digital states: High, Low and Floating. See Table 4-1.

3.6 Output Voltage Selection Control

Pin 1 (VSEL1) The Logic state of the V SEL1 and V SEL2 selects the output voltage. This input has three Digital states: High, Low and Floating. See Table 4-1.

3.7 Enable Pin (EN)

Logic high enables operation of the regulator. Logic low shuts down the device. In the OFF state, the supply current to the device is greatly reduced (typically 1.5 µA). The EN pin should not be left open.

3.8 Power Good Pin (PG)

This is an open-drain output that indicates when the output voltage is higher than the 91% limit. There is a 4% hysteresis, therefore, PG will return to low when the falling output voltage falls below 87% of the target regulation voltage.

3.9 Output Voltage Sense Pin (V OUT)

This pin is used to remote ly sense the output voltage. Connect it to VOUT as close to the output capacitor as possible to sense output voltage. This pin also provides the path to discharge the output through an internal 10 resistor when it is disabled.

3.10 Analog Ground Pin (A GND)

This is an internal signal ground for all low-power circuits. Connect it to ground plane. For the best load regulation, the connection path from AGND to the output capacitor ground terminal should be free from parasitic voltage drops.

3.11 EP1_P GND, EP2_PGND

These pins electrically connected to the P GND pins. They must be connected with thermal vias to the ground plane to ensure adequate heat sinking.

3.12 EP_SW Exposed Pad (SW)

This pin is electrically connected to the SW node.

3.13 OUT Exposed Pad (OUT)

This pin is electrically co nnected to the OUT pins. It must be externally connected to the output power connection.

 2020-2021 Microchip Technology Inc. DS20006348B-page 17 MIC33M350

4.0 DETAILED DESCRIPTION

4.1 Device Overview

The MIC33M350 device is a high-efficiency, 3A current, synchronous buck regulator power module with inte- grated inductor. The COT control architecture with automatic HyperLight Load m ode provides very high efficiency at light loads and ultra-fast transient response. The MIC33M350 output voltage is set by two V SEL three-state logic pins that can set the output voltage to nine different values (see Table 4-1). The 2.4V to 5.5V input voltage operating range makes the device ideal for single cell Li-ion battery-powered applications. The 100% duty cycle capability provides Low Dropout operation, ex tending battery life in portable systems. The au tomatic HyperLight Load mode provides very high efficiency at light loads. These devices focus on high output voltage accuracy. Total output error is less than 1.5% over line, load and temperature. MIC33M350 focuses on high output voltage accuracy. The MIC33M350 buck regulator uses an adaptive Constant On-Time control method. The adaptive on-time control scheme is employed to obtain a nearly constant switching frequency and to simplify the control compensation. Overcurrent protection is implemented without the use of an external sense resistor. The MIC33M350 device includes an internal soft start function which reduces the power supply input surge current at start-up by controlling the output voltage rise time.

4.2 HyperLight Load ® Mode (HLL)

HLL is a power-saving mode. In HLL, the switching frequency is not constant over the operation current range. At light loads, the minimum duty cycle is limited, which causes the switching frequency to decrease at light loads, this reduces switching and drive losses, and increases efficiency.

4.3 Enable (EN)

When the EN pin is pulled low, the IC is in a Shutdown state, with all internal circuits disabled and with the Power Good output low. During shutdown, the MIC33M350 part typically consumes 1.5 µA. When the EN pin is pulled high, the start-up sequence is initiated.

4.4 Power Good (PG)

The Power Good output is generally used for power sequencing, where the PG output is tied to the Enable output of another regulator. This technique avoids all the regulators powering up at the same time, which causes large inrush current. PG is an open-drain output that indicates that the output is above 87% of its voltage set value. During start-up, when the output voltage is rising, the Power Good output goes high when the output voltage reaches 91% of its set value. The Power Good threshold has 4% hysteresis, so the Power Good output stays high until th e output voltage falls below 87% of the set value. A built-in 65 µs blanking time is incorporated to prevent nuisance tripping. A pull-up resistor can be connected to V IN, VOUT, or an external source that is less than or equal to V IN. The PG pin can be connected to another regulator’s enable pin for sequencing of the ou tputs. The PG output is deasserted as soon as the Enable pin is pulled low or an input undervoltage condition, or any other Fault is detected.

4.5 Resistive Discharge (Soft

Discharge) To ensure a known output condition when the output is turned off, then back on again (i.e. in a brown output condition), the output is ac tively discharged to ground by means of an internal 10  resistor if the output is disabled.

DS20006348B-page 18  2020-2021 Microchip Technology Inc.

4.6 Output Voltage Setting

The MIC33M350 device has two pins, V SEL1 and VSEL2, which are used for choosing between nine predefined voltage settings: 0.6V, 0.8V, 0.9V, 1.0V, V IN, GND or left floating. The relationship between VSEL1/VSEL2 and the output voltage is shown in Table 4-1. VOUT should be connected exactly to the desired Point-of-Load (POL) regulation, avoiding parasitic resistive drops. It is possible to fine-tune the desired output voltage by adding a series resistor on the VOUT pin. This allows slightly higher output value programming, but should not exceed 5% deviation from the VSEL selected value. EQUATION 4-1:

4.7 Converter Stability/Output

The MIC33M350 device utilizes an internal compensation network and is designed to provide stable operation with output capacitors, from 47 µF to 1000 µF. This greatly simplifies the design, where you can add supplementary outp ut capacitance without having to worry about stability.

4.8 Soft Start

Excess bulk capacitance on the output can cause excessive input inrush cu rrent. The MIC33M350 soft start feature forces the output voltage to rise gradually, keeping the inrush current at reasonable levels. This is particularly important in battery-powered applications. When the Enable pin goes high, the output voltage starts to rise. Once the soft start period has finished, the Power Good comparator is enabled and the Power Good output goes high. The output voltage soft start time is determined by the soft start equation below. The Soft Start Time, t SS can be calculated by Equation 4-2. EQUATION 4-2: .

4.9 Dropout Operation

As the input voltage approaches the output voltage, the minimum on-time limits th e maximum duty cycle. To achieve 100% duty cycle, the high-side switch is latched when the duty cycle reaches around 92% and stays latched until the output voltage falls 4% below its regulated value. In drop out, the output voltage is determined by the input voltage minus the voltage drop across the high-side MOSFET. TABLE 4-1: OUTPUT VOLTAGE SETTINGS VSEL2 VSEL1 VOUT GND GND 0.6V GND OPEN 0.8V GND V IN 0.9V OPEN GND 1.0V OPEN OPEN 1.2V OPEN V IN 1.5V VIN GND 1.8V VIN OPEN 2.5V VIN VIN 3.3V RVOUT 8.2 k TRIM= Where: RVOUT =V OUT series resistance needed for a TRIM% output voltage increase tSS VOUT tRAMP= tss 800 s 0.8 ms== Where: VOUT =1 . 0 V tRAMP =8 0 0 µ s / V

 2020-2021 Microchip Technology Inc. DS20006348B-page 19 MIC33M350

4.10 Switching Frequency

The switching frequency of the MIC33M350 is determined by the internal On-Time (T ON) calculation. For an input voltage of 5V and an output voltage of 1V, the typical value of T ON is 180 ns. The resulting switching frequency can be estimated by Equation 4-3. EQUATION 4-3: Equation 4-3 is only valid in continuous conduction mode and for a lossless converter. In practice, losses cause an increase of the switching frequency compared to the ideal case. As the load current increases, losses increase too and so does the switching frequency. The on-time calculation is adaptive, in that the T ON value is modulated based on the input voltage and on the target output voltage to stabilize the switching frequency against their variations. Losses are not accounted for.

4.11 Undervoltage Protection (UVLO)

Undervoltage protection ensures that the IC has enough voltage to bias the internal circuitry properly and provide sufficient gate drive for the power MOSFETs. When the input voltage starts to rise, both power MOSFETs are off and the power good output is pulled low. The IC starts at approximately 2.225V and has a nominal 153 mV of hysteresis to prevent chattering between the UVLO high and low states.

4.12 Overtemperature Fault

The MIC33M350 monitors the die junction temperature to keep the IC operating properly. If the IC junction temperature exceeds +165°C, both power MOSFETs are immediately turned off. The IC is allowed to restart when the die temperature falls below +143°C. During recovery from a thermal shutdown event, if the regulator hits another th ermal shutdown event or a current limit event causing hiccup before Power Good can be achieved, the controller resets again. If this happens more than four times in a row, then the part enters the Latch-Off stat e, which turns off both MOSFETs permanently. The MIC33M350 part does not restart again unless the i nput power is cycled. This Latch-Off feature eliminates the thermal stress on the MIC33M350 during a persistent Fault event.

4.13 Safe Start-up Into a Pre-Biased

The MIC33M350 is designed for safe start-up into a pre-biased output in forced PWM. This feature prevents high negative inductor current flow in a pre-bias condition, which can damage the IC. This is achieved by not allowing forced PWM until the control loop commands eight swit ching cycles. After eight cycles, the low-side negative current limit is switched from 0A to -3A. The cycle counter is reset to zero if the enable pin is pulled low, or an input undervoltage condition or any other Fault is detected.

4.14 Current Limiting

The MIC33M350 regulator uses both high-side and low-side current sense for current limiting. When the high-side current sense threshold is reached, the high-side MOSFET is turned off and the low-side MOSFET is turned on. The low-side MOSFET stays on until the current falls to 80% of the high-side current threshold value, then the high side can be turned on again. If the overload condition lasts for more than four cycles, the MIC33M350 enters hiccup current limiting and both MOSFETs are turned off. There is a 1 ms cool-off period before the MOSFETs are allowed to be turned on. If the regulator has another hiccup event before it reaches the Power Good threshold on restart, turn both MOSFETs off again and wait for 1 ms. If this happens more than three times in a row, then the part enters the Latch-Off stat e, which turns off both MOSFETs permanently, unless the part is reset by cycling the input power.

4.15 Thermal Considerations

Although the MIC33M350 is capable of delivering up to 3A under load, the package thermal resistance and the device internal power dissipation may dictate some limitations to the continuous output current. If operated above the rated junction temperature, electrical parameters may drift beyond characterized specifications. The MIC33M350 is protected under all circumstances by thermal shutdown. VIN (V) V OUT (V) T ON 50 . 6 1 1 0 11 8 0 1.8 340 2.5 490 3.3 610 3.3 1 270 fSW VOUT VIN TON=

DS20006348B-page 20  2020-2021 Microchip Technology Inc. NOTES:

 2020-2021 Microchip Technology Inc. DS20006348B-page 21 MIC33M350

5.0 APPLICATION INFORMATION

5.1 Output Voltage Sensing

To achieve accurate output voltage regulation, the VOUT pin (internal feedback divider top terminal) should be Kelvin-connected as close as possible to the point of regulation top terminal. Since both the internal reference and the internal feedback divider’s bottom terminal refer to A GND, it is important to minimize voltage drops between the A GND and the point of regulation return terminal (typically the ground terminal of the output capacitor which is closest to the load).

5.2 Output Capacitor Selection

The type of the output capacitor is usually determined by its Equivalent Series Resistance (ESR). Voltage and RMS current capability are two other important factors for selecting the output capacitor. Recommended capacitor types are ceramic, low-ESR aluminum electrolytic, OS-CON, and POSCAP. The output capacitor’s ESR is usually the main cause of the output ripple. The output capacitor ESR also affects the control loop from a stability point of view. The maximum value of ESR is calculated using Equation 5-1. EQUATION 5-1: The peak-to-peak inductor current ripple can be calculated with the formula in Equation 5-2. EQUATION 5-2: The total output ripple is a combination of the ESR and output capacitance.The total ripple is calculated in Equation 5-3. EQUATION 5-3: The output capacitor RMS current is calculated in Equation 5-4. EQUATION 5-4: The power dissipated in the output capacitor is: EQUATION 5-5:

5.3 Input Capacitor Selection

The input capacitor for the power stage input V IN should be selected for ripple current rating and voltage rating. Tantalum input capacitors can fail when subjected to high inrush currents, caused by turning on the input supply. A tantalum input capacitor’s voltage rating should be at least two times the maximum input voltage, to maximize reliabi lity. Aluminum electrolytic, OS–CON, and multilayer pol ymer film capacitors can handle the higher inrush currents without voltage derating. The input voltage ripple depends on the input capacitor’s ESR. The peak input current is equal to the peak inductor current, as shown in Equation 5-6. EQUATION 5-6: The input capacitor must be rated for the input current ripple. The RMS value of input capacitor current is determined at the maximum output current. Assuming the peak-to-peak inductor current ripple is low: EQUATION 5-7: The power dissipated in the input capacitor is calculated in Equation 5-8. EQUATION 5-8: ESR COUT VOUT PP Where: VOUT(PP) Peak-to-peak output voltage ripple IL(PP) Peak-to-peak inductor current ripple IL(PP) VOUT VIN(MAX) VOUT– Where: L = 0.47 µH VOUT PP ILP P  2 ILP P  ESR COUT   2 Where: COUT Output Capacitance Value fSW Switching Frequency ICOUT RMS ILP P PDISS COUT ICOUT RMS

2 ESR COUT=

V IN ILP K CESR= PDISS CIN ICIN RMS

2 CESR=

DS20006348B-page 22  2020-2021 Microchip Technology Inc. NOTES:

 2020-2021 Microchip Technology Inc. DS20006348B-page 23 MIC33M350

6.0 PACKAGE MARKING INFORMATION

24-Lead QFN, 3.0 mm x 4.5 mm x 1.8 mm Legend: XX...X Customer-specific information Y Year code (last digit of calendar year) YY Year code (last 2 digits of calendar year) WW Week code (week of January 1 is week ‘01’) NNN Alphanumeric traceability code Pb-free JEDEC designator for Matte Tin (Sn) * This package is Pb-free. The Pb-free JEDEC designator ( ) can be found on the outer packaging for this package. Note: In the event the full Microchip part num ber cannot be marked on one line, it will be carried over to the next line, thus limiting the number of available characters for customer-specific information. Example 350 2110 256

DS20006348B-page 24  2020-2021 Microchip Technology Inc. BA 0.05 C 0.05 C C SEATING PLANE 2X TOP VIEW 0.08 C Microchip Technology Drawing C04-1220A Sheet 1 of 2 24X For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.com/packaging Note: 24-Lead Plastic Quad Flat, No Lead Package (N6A) - 3x4.5 mm Body [QFN] SIDE VIEW BOTTOM VIEW D E E (DATUM A) (DATUM B) NOTE 1

0.10 C A B

0.05 C 11X L D3 24X b e 6X L2 A (A3) 0.05 C NOTE 1 N N 2X b2 K1 0.20 K2 0.20

 2020-2021 Microchip Technology Inc. DS20006348B-page 25 MIC33M350 REF: Reference Dimension, usually without tolerance, for information purposes only. BSC: Basic Dimension. Theoretically exact value shown without tolerances. Notes: Pin 1 visual index feature may vary, but must be located within the hatched area. Package is saw singulated Dimensioning and tolerancing per ASME Y14.5M For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.com/packaging Note: Microchip Technology Drawing C04-1220A Sheet 2 of 2 24-Lead Plastic Quad Flat, No Lead Package (N6A) - 3x4.5 mm Body [QFN] Number of Terminals Overall Height Terminal Width Overall Width Terminal to Exposed Pad Exposed Pad Width Terminal Thickness Pitch Standoff Units Dimension Limits A b e E N

0.50 BSC

0.203 REF

2.35 0.20 0.20 1.80 0.00 0.25 2.40 1.85 0.02

4.50 BSC

2.45 0.30 1.90 0.05 MAX Overall Length Exposed Pad Length D D2 0.338

3.00 BSC

0.388 0.438 Exposed Pad Length D3 1.344 1.394 1.444 Exposed Pad Width E3 0.326 0.376 0.426 Terminal to Exposed Pad K2 0.20 - - b2 0.08 0.13 0.18Terminal Width Terminal Length L 0.35 0.40 0.45 Terminal Length L2 0.20 0.25 0.30

DS20006348B-page 26  2020-2021 Microchip Technology Inc. RECOMMENDED LAND PATTERN Dimension Limits Units Contact Pad Spacing Contact Pad Length (X7) Contact Pad Width (X24) Contact Pitch 0.30 3.00 MILLIMETERS E MAX 0.65 Exposed Pad Length X4 1.41 Microchip Technology Drawing C04-3220 Rev A NOM 24-Lead Plastic Quad Flat, No Lead Package (N6A) - 3x4.5 mm Body [QFN] Y1Contact Pad Length (X24) 0.80 Exposed Pad Width Y4 0.40 Thermal Via Diameter V Thermal Via Pitch EV 0.30 1.00 BSC: Basic Dimension. Theoretically exact value shown without tolerances. Notes: Dimensioning and tolerancing per ASME Y14.5M For best soldering results, thermal vias, if used, should be filled or tented to avoid solder loss during reflow process For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.com/packaging Note: E EV EV Y2 X5 EV 8X ØV SILK SCREEN EV Exposed Pad Width X5 0.43 Exposed Pad Length Y5 2.40 Terminal to Exposed Pad X6 0.20 Terminal to Exposed Pad Y6 0.50 Contact Pad Spacing C2 4.50 X3Contact Pad Width 0.20 Terminal to Exposed Pad Y7 0.20 Outer Features Inner Features

 2020-2021 Microchip Technology Inc. DS20006348B-page 27 MIC33M350 APPENDIX A: REVISION HISTORY Revision B (March 2021) The following is the list of modifications: 1. Added edits to incorporate the AEC-Q104 qualification. Revision A (May 2020)

• Initial release of this document.

 2020-2021 Microchip Technology Inc. DS20006348B-page 28 MIC33M350 NOTES:

 2020-2021 Microchip Technology Inc. DS20006348B-page 29 MIC33M350 PRODUCT IDENTIFICATION SYSTEM To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office. PART NO. X XX PackageDevice Device: MIC33M350 Junction Temperature Range: Y= - 4 0 C to +125C (Extended) Package: MP = QFN (Plastic Quad Flat, No Lead Package) Tape and Reel Option: Blank = Tube TR = Tape and Reel Qualification: Blank = Tube VAO = AEC-Q104 Automotive Qualification Vxx = AEC-Q104 Automotive Qualification; custom device, additional terms or conditions may apply. Examples: a) MIC33M350YMP-TR: Extended Temperature, 24-Lead QFN package, Tape and Reel b) MIC33M350YMP-VAO: Extended Temperature 24-Lead QFN package, Tape and Reel, Automotive Qualified c) MIC33M350YMP-TRVAO: Extended Temperature, 24-Lead QFN package, Tape and Reel, Automotive Qualified Note 1: Tape and Reel identifier only appears in the catalog part number description. This identifier is used for ordering purposes and is not printed on the device package. Check with your Microchip Sales Office for package availability with the Tape and Reel option. XX Tape and Reel Option(1) Junction Temperature Range XXX Qualification

DS20006348B-page 30  2020-2021 Microchip Technology Inc. NOTES:

 2020-2021 Microchip Technology Inc. DS20006348B-page 31 Information contained in this publication is provided for the sole purpose of designing with and using Microchip products. Infor- mation regarding device applications and the like is provided only for your convenience and may be superseded by updates. It is your responsibility to ens ure that your application meets with your specifications. THIS INFORMATION IS PROVIDED BY MICROCHIP "AS IS". MICROCHIP MAKES NO REPRESENTATIONS OR WAR- RANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED, WRITTEN OR ORAL, STATUTORY OR OTHERWISE, RELATED TO THE INFORMATION INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTIES OF NON- INFRINGEMENT, MERCHANTABILITY, AND FITNESS FOR A PARTICULAR PURPOSE OR WARRANTIES RELATED TO ITS CONDITION, QUALITY, OR PERFORMANCE. IN NO EVENT WILL MICROCHIP BE LIABLE FOR ANY INDI- RECT, SPECIAL, PUNITIVE, INCIDENTAL OR CONSEQUEN- TIAL LOSS, DAMAGE, COST OR EXPENSE OF ANY KIND WHATSOEVER RELATED TO THE INFORMATION OR ITS USE, HOWEVER CAUSED, EVEN IF MICROCHIP HAS BEEN ADVISED OF THE POSSIBILITY OR THE DAMAGES ARE FORESEEABLE. TO THE FULLEST EXTENT ALLOWED BY LAW, MICROCHIP'S TOTAL LIABILITY ON ALL CLAIMS IN ANY WAY RELATED TO THE INFORMATION OR ITS USE WILL NOT EXCEED THE AMOUNT OF FEES, IF ANY, THAT YOU HAVE PAID DIRECTLY TO MICROCHIP FOR THE INFORMATION. Use of Microchip devices in life sup- port and/or safety applications is entirely at the buyer's risk, and the buyer agrees to defend, indemnify and hold harmless Microchip from any and all damages, claims, suits, or expenses resulting from such use. No licenses are conveyed, implicitly or otherwise, under any Microchip intellectu al property rights unless otherwise stated. Trademarks The Microchip name and logo, the Microchip logo, Adaptec, AnyRate, AVR, AVR logo, AVR Freaks, BesTime, BitCloud, chipKIT, chipKIT logo, CryptoMemory, CryptoRF, dsPIC, FlashFlex, flexPWR, HELDO, IGLOO, JukeBlox, KeeLoq, Kleer, LANCheck, LinkMD, maXStylus, maXTouch, MediaLB, megaAVR, Microsemi, Microsemi logo, MOST, MOST logo, MPLAB, OptoLyzer, PackeTime, PIC, picoPower, PICSTART, PIC32 logo, PolarFire, Prochip Designer, QTouch, SAM-BA, SenGenuity, SpyNIC, SST, SST Logo, SuperFlash, Symmetricom, SyncServer, Tachyon, TimeSource, tinyAVR, UNI/O, Vectron, and XMEGA are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. AgileSwitch, APT, ClockWorks, The Embedded Control Solutions Company, EtherSynch, FlashTec, Hyper Speed Control, HyperLight Load, IntelliMOS, Libero, motorBench, mTouch, Powermite 3, Precision Edge, ProASIC, ProASIC Plus, ProASIC Plus logo, Quiet- Wire, SmartFusion, SyncWorld, Temux, TimeCesium, TimeHub, TimePictra, TimeProvider, WinPath, and ZL are registered trademarks of Microchip Technology Incorporated in the U.S.A. Adjacent Key Suppression, AKS, Analog-for-the-Digital Age, Any Capacitor, AnyIn, AnyOut, Augmented Switching, BlueSky, BodyCom, CodeGuard, CryptoAuthentication, CryptoAutomotive, CryptoCompanion, CryptoController, dsPICDEM, dsPICDEM.net, Dynamic Average Matching, DAM, ECAN, Espresso T1S, EtherGREEN, IdealBridge, In-Circuit Serial Programming, ICSP, INICnet, Intelligent Paralleling, Inter-Chip Connectivity, JitterBlocker, maxCrypto, maxView, memBrain, Mindi, MiWi, MPASM, MPF, MPLAB Certified logo, MPLIB, MPLINK, MultiTRAK, NetDetach, Omniscient Code Generation, PICDEM, PICDEM.net, PICkit, PICtail, PowerSmart, PureSilicon, QMatrix, REAL ICE, Ripple Blocker, RTAX, RTG4, SAM-ICE, Serial Quad I/O, simpleMAP , SimpliPHY , SmartBuffer, SMART-I.S., storClad, SQI, SuperSwitcher, SuperSwitcher II, Switchtec, SynchroPHY, Total Endurance, TSHARC, USBCheck, VariSense, VectorBlox, VeriPHY, ViewSpan, WiperLock, XpressConnect, and ZENA are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. SQTP is a service mark of Microchip Technology Incorporated in the U.S.A. The Adaptec logo, Frequency on Demand, Silicon Storage Technology, and Symmcom are registered trademarks of Microchip Technology Inc. in other countries. GestIC is a registered trademark of Microchip Technology Germany II GmbH & Co. KG, a subsidiary of Microchip Technology Inc., in other countries. All other trademarks mentioned herein are property of their respective companies. © 2020-2021, Microchip Technology Incorporated, All Rights Reserved. ISBN: 978-1-5224-7800-3 Note the following details of the code protection feature on Microchip devices:

• Microchip products meet the specifications c ontained in their particular Microchip Data Sheet.
• Microchip believes that its family of products is secu re when used in the intended manner and under normal conditions.
• There are dishonest and possibly illegal methods being used in attempts to breach the code protection features of the Microchip devices. We believe that these methods require using the Microchip products in a manner outside the operating specifications contained in Microchip's Data Sheets. Attempts to breach these code protection features, most likely, cannot be accomplished without violating Microchip's intellectual property rights.
• Microchip is willing to work with any customer who is concerned about the integrity of its code.
• Neither Microchip nor any other semic onductor manufacturer can guarantee the security of its code. Code protection does not mean that we are guaranteeing the product is "unbreakable." Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our products. Attempts to break Microchip's code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act. For information regarding Microchip’s Quality Management Systems, please visit www.microchip.com/quality.

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