MAX20004

DATASHEET SEARCH SITE | WWW.ALLDATASHEET.COM

Document overview

Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
PDF pages: 20

Technical content

The MAX20004/MAX20006/MAX20008 are small, synchro- nous, automotive buck converter devices with integrated high-side and low-side MOSFETs. The device family can deliver up to 8A with input voltages from 3.5V to 36V, while using only 25μA quiescent current at no load. Voltage qual- ity can be monitored by observing the RESET signal. The devices can operate in dropout by running at 98% duty cycle, making them ideal for automotive applications. The devices offer fixed output voltages of 5V and 3.3V, along with the ability to program the output voltage between 1V and 10V. Frequency is resistor programmable from 220kHz to 2.2MHz. The devices offer a forced fixed-fre- quency PWM mode (FPWM) and skip mode with ultra-low quiescent current. The devices can be factory programmed to enable spread-spectrum switching to reduce EMI. The MAX20004/MAX20006/MAX20008 are available in a small, 3.5mm x 3.75mm, 17-pin FC2QFN package and use very few external components.

Applications

Point-of-Load (PoL) Applications in Automotive
Distributed DC Power Systems
Navigation and Radio Head Units Benefits and Features
Multiple Functions for Small Size
Operating VIN Range of 3.5V to 36V
25µA Quiescent Current in Skip Mode
Synchronous DC-DC Converter with Integrated FETs
220kHz to 2.2MHz Adjustable Frequency
Fixed 5ms Internal Soft-Start
Programmable 1V to 10V Output, or 3.3V and 5.0V Fixed-Output Options Available
98% Duty-Cycle Operation with Low Dropout
RESET Output
High Precision
±2% Output-Voltage Accuracy
Good Load-Transient Performance
Robust for the Automotive Environment
Current-Mode, Forced-PWM and Skip Operation
Overtemperature and Short-Circuit Protection
3.5mm x 3.75mm 17-Pin FC2QFN
-40°C to +125°C Operating Temperature Range
40V Load-Dump Tolerant
AEC-Q100 Qualified Ordering Information appears at end of data sheet. 19-100239; Rev 8; 11/19 MAX20004/MAX20006/ MAX20008 36V, 220kHz to 2.2MHz, 4A/6A/8A Fully Integrated Automotive Step-Down Converters Typical Application Circuit CI N1 4.7µF L 1µH CBIAS 2.2 µF SUP EN SYNC RESET LX PGND BST BIAS GND OUT SUPSW FB 0.1 µF COUT CI N2 0.1µF RRESET 20 kΩ CBS T VOUT FOSC COMP BIAS 12 kΩ 22 kΩ 1n F 4.7 pF Click here for production status of specific part numbers.

Continuous Power Dissipation (TA = +70°C) (VSUP = VSUPSW = VEN = 14V. TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at T A = +25°C under normal conditions, unless otherwise noted.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Supply Voltage Range VSUP, VSUPSW 3.5 36 V Supply Voltage Range VSUP, VSUPSW After startup 3.0 V Supply Current ISUP Skip mode, no load VOUT = 3.3V 25 32 µA VOUT = 5.0V 30 42 Shutdown Supply Current ISHDN VEN = 0V 5 10 µA BIAS Regulator Voltage VBIAS VSUP = VSUPSW = 6V to 40V IBIAS < 10mA, BIAS not switched over to VOUT 5 V BIAS Undervoltage Lockout VUVBIAS VBIAS rising 2.7 3 3.3 V

17 FC2QFN

Land Pattern Number 90-100056 Thermal Resistance, Four-Layer Board: Junction to Ambient (θJA) 27°C/W Junction to Case (θJC) 2.6°C/W MAX20004/MAX20006/ MAX20008 36V, 220kHz to 2.2MHz, 4A/6A/8A Fully Integrated Automotive Step-Down Converters www.maximintegrated.com Maxim Integrated │ 2 Note 1: Self-protected from transient voltages exceeding these limits in circuit under normal operation. Absolute Maximum Ratings Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

Package Information

Electrical Characteristics

For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. Package thermal resistances were obtained using the EV kit. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.

(VSUP = VSUPSW = VEN = 14V. TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at T A = +25°C under normal conditions, unless otherwise noted.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS BIAS Undervoltage Lockout VUVBIAS VBIAS falling 2.5 2.9 V Thermal-Shutdown Temperature TSHDN TJ rising 175 °C Thermal-Shutdown Hysteresis T HYST 15 °C OUTPUT VOLTAGE PWM-Mode Output Voltage (Note 3) VOUT_5V VSUP = VSUPSW = 6V to 28V 4.9 5 5.1 V Skip-Mode Output Voltage (Note 4) V SKIP_5V Skip mode, no load, FB = BIAS 4.9 5 5.15 V PWM-Mode Output Voltage V OUT_3.3V VSUP = VSUPSW = 6V to 28V 3.23 3.3 3.37 V Skip-Mode Output Voltage (Note 4) V SKIP_3.3V Skip mode, no load, FB = BIAS 3.23 3.3 3.4 V Load Regulation LNREG VFB = VBIAS, 30mA < ILOAD < 6A, PWM mode, 5V 0.6 % Line Regulation LDREG VFB = VBIAS, 6V < VSUPSW < 36V, PWM mode 0.02 %/V BST Input Current IBST_ON High-side MOSFET on, VBST - VLX = 5V 1.5 mA BST Input Current IBST_OFF High-side MOSFET off, VBST - VLX = 5V 0.1 µA LX Current Limit ILX MAX20004 (4A) 5.25 7 8.75 AMAX20006 (6A) 7.5 10 12.5 MAX20008 (8A) 10.5 14 17.5 LX Rise Time (Note 4) tLX_TR 2 ns Spread Spectrum SS Spread spectrum enabled ±3 % High-Side Switch On-Resistance RHS VBIAS = 5V, ILX = 2A 38 76 mΩ High-Side Switch Leakage IHS_LKG High-side MOSFET off, VSUPSW = 36V, VLX = 0V, TA = +25°C 1 5 µA Low-Side Switch On-Resistance RLS VBIAS = 5V, ILX = 2A 18 36 mΩ Low-Side Switch Leakage ILS_LKG Low-side MOSFET off, VSUPSW = 36V, VLX = 36V, TA = +25°C 1 5 µA FB Input Current IFB TA = +25°C 30 100 nA FB Regulation Voltage VFB FB connected to an external resistive divider, 6V < V SUPSW < 36V 0.99 1.00 1.01 V Transconductance (from FB to COMP) gm VFB = 1V, VBIAS = 5V 500 780 1000 µS Minimum On-Time (Note 4) tON_MIN Load 500mA (Note 4) 75 ns MAX20004/MAX20006/ MAX20008 36V, 220kHz to 2.2MHz, 4A/6A/8A Fully Integrated Automotive Step-Down Converters www.maximintegrated.com Maxim Integrated │ 3 Electrical Characteristics (continued)

Note 2: All units are 100% production tested at T A = +25˚C. All temperature limits are guaranteed by design. Note 3: Device not in dropout condition. Note 4: Guaranteed by design. Not production tested. Note 5: Contact factory for SYNC frequency outside the specified range. Note 6: Contact factory for additional options. (VSUP = VSUPSW = VEN = 14V. TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at T A = +25°C under normal conditions, unless otherwise noted.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Maximum Duty Cycle DCMAX 97 98 % Oscillator Frequency fSW1 RFOSC = 73.2kΩ 360 400 440 kHz Oscillator Frequency fSW2 RFOSC = 12kΩ 2.0 2.2 2.4 MHz Soft-Start Time tSS 5 ms EN, SYNC External Input Clock Frequency RFOSC = 12kΩ (Note 5) 1.8 2.6 MHz SYNC High Threshold VSYNC_HI 1.4 V SYNC Low Threshold VSYNC_LO 0.4 V SYNC Leakage Current ISYNC TA = +25°C 0.1 1 µA EN High Threshold VEN_HI 2.4 V EN Low Threshold VEN_LO 0.6 V EN Hysteresis VEN_HYS 0.2 V EN Leakage Current IEN TA = +25°C 0.1 2 µA RESET UV Threshold UVACC Falling 89 91 93 % UV Hysteresis 3 % Hold Time (Note 6) tHOLD1 (Note 6) 0.2 ms UV Debounce Time tDEB 25 µs OV Protection Threshold OVPTHR Rising 104 107 110 % OV Protection Threshold OVPTHF Falling 105 % Leakage Current IRST_LKG VOUT in regulation, TA = +25°C 1 µA Output Low Level VROL ISINK = 5mA 0.4 V MAX20004/MAX20006/ MAX20008 36V, 220kHz to 2.2MHz, 4A/6A/8A Fully Integrated Automotive Step-Down Converters www.maximintegrated.com Maxim Integrated │ 4 Electrical Characteristics (continued)

(VSUP = VSUPSW = 14V, VEN = 14V, VOUT = 5V, VFSYNC = 0V, RFOSC = 12kΩ, TA = +25°C, unless otherwise noted.) 100 0.001 0.01 0.1 1 10 EFFICIENCY (%) LOAD CURRENT (A) VIN = 12V VOUT = 5V fSW = 2.2MHz EFFICIENCY vs. LOAD CURRENT toc03 PWM MODE SKIP MODE 100 0.001 0.01 0.1 1 10 EFFICIENCY (%) LOAD CURRENT (A) VIN = 12V VOUT = 5V fSW = 400kHz EFFICIENCY vs. LOAD CURRENT toc01 PWM MODE SKIP MODE 6 9 12 15 18 21 24 27 30 33 36 SUPPLY CURRENT (uA) SUPPLY VOLTAGE (V) SHUTDOWN CURRENT vs. SUPPLY VOLTAGE toc05 VEN = 0V 100 0.001 0.01 0.1 1 10 EFFICIENCY (%) LOAD CURRENT (A) VIN = 12V VOUT = 3.3V fSW = 400kHz EFFICIENCY vs. LOAD CURRENT toc02 PWM MODE SKIP MODE 6 9 12 15 18 21 24 27 30 33 36 SUPPLY CURRENT (uA) SUPPLY VOLTAGE (V) NO LOAD SUPPLY CURRENT vs. SUPPLY VOLTAGE toc06 VOUT = 3.3V fSW = 2.2MHz SKIP MODE 100 0.001 0.01 0.1 1 10 EFFICIENCY (%) LOAD CURRENT (A) VIN = 12V VOUT = 3.3V fSW = 2.2MHz EFFICIENCY vs. LOAD CURRENT toc04 PWM MODE SKIP MODE Maxim Integrated │ 5 www.maximintegrated.com MAX20004/MAX20006/ MAX20008 36V, 220kHz to 2.2MHz, 4A/6A/8A Fully Integrated Automotive Step-Down Converters Typical Operating Characteristics

(VSUP = VSUPSW = 14V, VEN = 14V, VOUT = 5V, VFSYNC = 0V, RFOSC = 12kΩ, TA = +25°C, unless otherwise noted.) 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 VBIAS (V) VSUP (V) VBIAS vs. VSUP toc09 VOUT = 3.3V fSW = 2.2MHz IOUT = 0.1A IOUT = 6A 250 500 750 1000 1250 1500 1750 2000 2250 2500 10 30 50 70 90 110 130 150 SWITCHING FREQUENCY (kHz) ROSC (kΩ) SWITCHING FREQUENCY vs. R FOSC toc07 4.80 4.85 4.90 4.95 5.00 5.05 5.10 5.15 5.20 0 1 2 3 4 5 6 7 8 VOUT (V) IOUT (A) LOAD REGULATION toc11 VIN = 14V PWM MODE 400kHz 2.2MHz 5V/div 1V/div toc08 200ns/div VLX VSYNC SYNC FUNCTION 4.80 4.85 4.90 4.95 5.00 5.05 5.10 5.15 5.20 0 1 2 3 4 5 6 7 8 VOUT (V) IOUT (A) LOAD REGULATION toc12 VIN = 14V SKIP MODE 400kHz 2.2MHz 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0 1 2 3 4 5 6 DROPOUT VOLTAGE (V) IOUT (A) DROPOUT VOLTAGE vs. I OUT toc10 VOUT = 95% of VSET L = COILCRAFT XAL6030-102 VSET = 5V VSET = 3.3V Typical Operating Characteristics Maxim Integrated │ 6 www.maximintegrated.com MAX20004/MAX20006/ MAX20008 36V, 220kHz to 2.2MHz, 4A/6A/8A Fully Integrated Automotive Step-Down Converters

(VSUP = VSUPSW = 14V, VEN = 14V, VOUT = 5V, VFSYNC = 0V, RFOSC = 12kΩ, TA = +25°C, unless otherwise noted.) 10V/div 5V/div toc15 4ms/div VIN IOUT VIN STARTUP BEHAVIOR VOUT VRESET 2V/div 2A/div EN = VIN 4.99 5.00 5.01 5.02 5.03 5.04 5.05 6 12 18 24 30 36 VOUT (V) VIN (V) VOUT vs. VIN toc13 PWM MODE ILOAD = 0A 400kHz 2.2MHz 100 110 120 130 140 1 2 3 4 5 6 7 8 TJ_RISE (°C) IOUT (A) TJ_RISE vs. IOUT toc17 fSW = 2.2MHz VIN = 14V PWM MODE TA = 25°C VOUT = 5V VOUT = 3.3V 5V/div 5V/div toc14 4ms/div VEN IOUT ENABLE STARTUP BEHAVIOR VOUT VRESET 2V/div 2A/div VIN = 14V 1 2 3 4 5 6 7 8 TJ_RISE (°C) IOUT (A) TJ_RISE vs. IOUT toc18 fSW = 400kHz VIN = 14V PWM MODE TA = 25°C VOUT = 5V VOUT = 3.3V 2V/div 10V/div 20A/div toc16 20ms/div VOUT VLX SHORT CIRCUIT AND RECOVERY IOUT Typical Operating Characteristics Maxim Integrated │ 7 www.maximintegrated.com MAX20004/MAX20006/ MAX20008 36V, 220kHz to 2.2MHz, 4A/6A/8A Fully Integrated Automotive Step-Down Converters

1 OUT Switching Regulator Output. OUT also provides power to the internal circuitry under certain conditions (see the Linear Regulator Output (BIAS) section for details). 2 RESET Open-Drain, Active-Low RESET Output. To obtain a logic signal, pullup RESET with an external resistor. 3 BST High-Side Driver Supply. Connect a 0.1μF capacitor between LX and BST for proper operation. 4, 5, 7, 8 PGND Power Ground. Connect all PGND pins together. 6 LX Inductor Connection. Connect LX to the switched side of the inductor.

9 SUPSW

Internal High-Side Switch Supply Input. SUPSW provides power to the internal switch. Bypass SUPSW to PGND with 0.1μF and 4.7μF ceramic capacitors. Place the 0.1μF capacitor as close as possible to the SUPSW and PGND pins, followed by the 4.7μF capacitor. 10 SUP Voltage Supply Input. SUP supplies the internal linear regulator. Connect SUP directly to SUPSW as close as possible to the IC. SUP and SUPSW are connected together internally. 11 EN SUP Voltage-Compatible Enable Input. Drive EN low to disable the device. Drive EN high to enable the device. For a safe startup, ensure that VSUP > 7.5V when EN is toggled high.

12 SYNC

Connect SYNC to GND or leave unconnected to enable skip-mode operation under light loads. Connect SYNC to BIAS or to an external clock to enable fixed-frequency forced-PWM-mode operation. When driving SYNC externally, do not exceed the BIAS or OUT voltage. 13 BIAS Linear Regulator Output. BIAS supplies the internal circuitry. Bypass with a minimum 2.2 µF ceramic capacitor to ground. The BIAS pin can transition from 5V to VOUT after startup.

14 GND Analog Ground

36V, 220kHz to 2.2MHz, 4A/6A/8A Fully Integrated Automotive Step-Down Converters www.maximintegrated.com Maxim Integrated │ 8 Pin Configuration Pin Description TOP VIEW FC2QFN 3.5mm x 3.75mm 3 9 5 7 4 8 FOSC 16 FB

15 COMP

14 GND

13 BIAS

15 COMP Error-Amplifier Output. Connect an RC network from COMP to GND for stable operation. See the Compensation Network section for more details. 16 FB Feedback Input. Connect an external resistive divider from OUT to FB and GND to set the output voltage. Connect FB to BIAS to set the output voltage to 5V or 3.3V. 17 FOSC Resistor-Programmable Switching Frequency Setting Control Input. Connect a resistor from FOSC to GND to set the switching frequency. MAX20004/MAX20006/ MAX20008 36V, 220kHz to 2.2MHz, 4A/6A/8A Fully Integrated Automotive Step-Down Converters www.maximintegrated.com Maxim Integrated │ 9 Internal Block Diagram Pin Description (continued) SKIP CURRENT COMP PEAK CURRENT COMP PWM COMP CONTROL LOGIC CURRENT-SENSE AMP BST LX BIAS PGND SUPSW LX PGND ZX COMP CLKFPWM RAMP GENERATOR CLK SOFT-START GENERATOR VREF POK PGOOD COMP ERROR AMPFEEDBACK SELECTFB MAIN CONTROL LOGIC VOLTAGE REFERENCE OTP OSC CLK FPWM SYNC EN POK RESET TRIMBITS VREF SEL GND BIAS LDO SUP BIAS FOSC GND COMP OUT MAX20004 MAX20006 MAX20008

The MAX20004/MAX20006/MAX2008 are 4A, 6A, and 8A current-mode step-down converters, respectively, with integrated high-side and low-side MOSFETs. The low-side MOSFET enables fixed-frequency FPWM opera- tion in light-load applications. The devices operate with 3.5V to 36V input voltages, while using only 25μA (typ) quiescent current at no load. The switching frequency is resistor programmable from 220kHz to 2.2MHz and can be synchronized to an external clock. The devices’ output voltage is available as fixed 5V or 3.3V, or adjust - able between 1V and 10V. The wide input voltage range, along with the ability to operate at 99% duty cycle during undervoltage transients, make these devices ideal for automotive applications. In light-load applications, a logic input (SYNC) allows the devices to operate either in skip mode for reduced current consumption, or fixed-frequency FPWM mode to eliminate frequency variation and help minimize EMI. Protection features include cycle-by-cycle current limit, and thermal shutdown with automatic recovery. Thermal Considerations The devices are available in 4A, 6A, or 8A versions; how- ever, the average output-current capability is dependent on several factors. Some of the key factors include the maxi- mum ambient temperature (TA(MAX)), switching frequency (fSW), and the number of layers and the size of the PCB. See the Typical Operating Characteristics for a guideline. Wide Input Voltage Range The devices include two separate supply inputs (SUP and SUPSW) specified for a wide 3.5V to 36V input voltage range. VSUP provides power to the device and V SUPSW provides power to the internal switch. When the device is operating with a 3.5V input supply, conditions such as cold crank can cause the voltage at the SUP and SUPSW pins to drop below the programmed output voltage. Under such conditions, the devices operate in a high duty-cycle mode to facilitate minimum dropout from input to output. Maximum Duty-Cycle Operation The devices have an effective maximum duty cycle of 98% (typ). The IC continuously monitors the time between low- side FET switching cycles in both PWM and skip modes. Whenever the low-side FET has not switched for more than 13.5µs (typ), the low-side FET is forced on for 150ns (typ) to refresh the BST capacitor. The input voltage at which the device enters dropout changes depending on the input voltage, output voltage, switching frequency, load current, and the efficiency of the design. The input voltage at which the device enters dropout can be approximated as: OUTSUP OUT HS VV IR 0.98= +× where R HS is the high-side switch on-resistance, which should also include the inductor DC resistance for better accuracy. Linear Regulator Output (BIAS) The devices include a 5V linear regulator (V BIAS) that provides power to the internal circuit blocks. Connect a 2.2μF ceramic capacitor from BIAS to GND. Under certain conditions, the BIAS regulator turns off and the BIAS pin switches to OUT (i.e., switches over) after startup to increase efficiency. For IC versions that are factory trimmed for 3.3V fixed output, BIAS switches to OUT under light load conditions in skip mode only. For IC versions that are factory trimmed for 5V fixed output, the BIAS pin switches to OUT after startup regardless of load or skip/PWM mode. In any case, BIAS only switches over if OUT is between 2.8V and 5.6V. In summary, BIAS can transition from 5V to VOUT after startup depending on load, mode and IC version. Soft-Start The devices include a fixed, internal soft-start. Soft-start limits startup inrush current by forcing the output voltage to ramp up towards its regulation point. Reset Output (RESET) The devices feature an open-drain reset output (RESET). RESET asserts when V OUT drops below the specified falling threshold. RESET deasserts when V OUT rises above the specified rising threshold after the specified hold time. Connect RESET to the output or I/O voltage of choice (within pin voltage limits) with a pullup resistor. Synchronization Input (SYNC) SYNC is a logic-level input used for operating-mode selection and frequency control. Connecting SYNC to BIAS or to an external clock enables forced fixed-frequen- cy (FPWM) operation. Connecting SYNC to GND enables automatic skip-mode operation for light load efficiency. The external clock frequency at SYNC can be higher or lower than the internal clock by 20%. If the external clock frequency is greater than 120% of the internal clock, con- tact the factory to verify the design. The devices synchro- nize to the external clock in two cycles. When the external clock signal at SYNC is absent for more than two clock cycles, the devices use the internal clock. There is a diode MAX20004/MAX20006/ MAX20008 36V, 220kHz to 2.2MHz, 4A/6A/8A Fully Integrated Automotive Step-Down Converters www.maximintegrated.com Maxim Integrated │ 10

between SYNC and BIAS, so it is important when driving SYNC with an external source that the voltage be less than or equal to BIAS (or OUT in the case of switchover). If this cannot be guaranteed, place a series resistor in-line with SYNC ≥ 20kΩ to limit the input current. If EN is low, BIAS is turned off so a voltage should not be present on SYNC without the series resistor. System Enable (EN) An enable control input (EN) activates the devices from their low-power shutdown mode. EN is compatible with inputs from automotive battery level down to 3.5V. EN turns on the internal linear (BIAS) regulator. Once VBIAS is above the internal lockout threshold (V UVBIAS = 3V (typ)), the converter activates and the output voltage ramps up with the programmed soft-start time. A logic-low at EN shuts down the device. During shut - down, the BIAS regulator and gate drivers turn off. Shutdown is the lowest power state and reduces the quiescent current to 5μA (typ). Drive EN high to bring the device out of shutdown. For safe startup, ensure that V SUP > 7.5V when EN is toggled high. In all applications, BIAS capacitance guide - lines must be followed to ensure safe operation of the IC. Note: In all applications, BIAS must start from < 0.3V or > 1.6V during startup. Spread-Spectrum Option The devices can be ordered with spread spectrum enabled. See the Ordering Information/Selector Guide section. When the spread spectrum is factory enabled, the operating frequency is varied ±3% centered on FOSC. The modulation signal is a triangular wave with a fre - quency of 4.5kHz at 2.2MHz. For operations at FOSC values other than 2.2MHz, the modulation signal scales proportionally (e.g., at 400kHz, the modulation frequency reduces by 0.4MHz/2.2MHz). The internal spread spectrum is disabled if the devices are synchronized to an external clock. However, the devices do not filter the input clock on the SYNC pin and pass any modulation (including spread spectrum) present driving the external clock. Internal Oscillator (FOSC) The switching frequency (f SW) is set by a resistor (RFOSC) connected from FOSC to GND. To determine the approximate value of RFOSC for a given fSW, use the graph in the Typical Operating Characteristics section or the following equation: FOSC SW 29,600R 1.48f= − where fSW is in kHz and RFOSC is in kΩ. For example, a 400kHz switching frequency is set with R FOSC = 72.5kΩ. Higher frequencies allow designs with lower inductor values and less output capacitance at the expense of reduced efficiency and higher EMI. Thermal-Shutdown Protection Thermal shutdown protects the device from excessive operating temperature. When the junction temperature exceeds the specified threshold, an internal sensor shuts down the internal bias regulator and the step-down con - verter, allowing the IC to cool. The sensor turns the IC on again after the junction temperature cools by the specified hysteresis. Current Limit/Short-Circuit Protection The devices feature a current limit that protects them against short-circuit and overload conditions at the out - put. In the event of a short-circuit or overload condition, the high-side MOSFET remains on until the inductor current reaches the specified LX current-limit threshold. The converter then turns the high-side MOSFET off and the low-side MOSFET on to allow the inductor current to ramp down. Once the inductor current crosses below the current-limit threshold, the converter turns on the high- side MOSFET again. This cycle repeats until the short or overload condition is removed. A hard short is detected when the output voltage falls below 50% of the target while in current limit. If this occurs, hiccup mode activates, and the output turns off for four times the soft-start time. The output then enters soft-start and powers back up. This repeats indefinitely while the short circuit is present. Hiccup mode is disabled during soft-start. Overvoltage Protection If the output voltage exceeds the OV protection rising threshold, the high-side MOSFET turns off and the low- side MOSFET turns on. Normal operation resumes when the output voltage goes below the falling OV threshold. MAX20004/MAX20006/ MAX20008 36V, 220kHz to 2.2MHz, 4A/6A/8A Fully Integrated Automotive Step-Down Converters www.maximintegrated.com Maxim Integrated │ 11

Electrical Characteristics table. to ensure full output current capability. the converter’s switching frequency is load-dependent. and switching losses are lower and efficiency is increased. device, not the maximum load current in the application. Figure 1. Adjustable Output-Voltage Setting

To satisfy both LMIN1 and LMIN2, LMIN must be set to the larger of the two as follows: ( )MIN MIN1 MIN2L max L , L= The maximum nominal inductor value recommended is 2 times the chosen value from the above formula: MAX MINL 2 L= × Select a nominal inductor value based on the following formula: MIN NOM MAXLL L << The best choice of inductor is usually the standard induc - tor value closest to LNOM. Input Capacitor The input filter capacitor reduces peak currents drawn from the power source and reduces noise and voltage ripple on the input due to high speed switching. Place a 0.1μF capacitor as close as possible to the SUPSW and PGND pins, followed by a 4.7μF (or larger) ceramic capacitor. A bulk capacitor with higher ESR (such as an electrolytic capacitor) is normally required as well to lower the Q of the front-end circuit and provide the remaining capacitance needed to minimize input voltage ripple. The input capacitor RMS current requirement (I RMS) is defined by the following equation: ( )OUT SUP OUT RMS LOAD(MAX) SUP V VV II V = × IRMS has a maximum value when the input voltage equals twice the output voltage: SUP OUTV 2V = × therefore: ( )LOAD MAX RMS I I 2= Choose an input capacitor that exhibits less than +10°C self-heating temperature rise at the RMS input current for optimal long-term reliability. The input-voltage ripple is composed of ∆V Q (caused by the capacitor discharge) and ∆VESR (caused by the ESR of the capacitor). Use low-ESR ceramic capacitors with high ripple-current capability at the input. Calculate the input capacitance and ESR required for a specified input voltage ripple using the following equations: LOT IN U ESRVESR II 2 ∆= ∆+ where: ( )SUP OUT OUT L SUP SW VV VI Vf L and: ( )OUT IN Q SW I D1 DC Vf ×−= ∆× OUT SUPSW VD V= where: IOUT is the maximum output current and D is the duty cycle. Output Capacitor The output filter capacitor must have enough capacitance and sufficiently low ESR to meet output-ripple require - ments. In addition, the output capacitance must be high enough to maintain the output voltage within specification while the control loop responds to load changes. When using high-capacitance, low-ESR capacitors, the filter capacitor’s ESR dominates the output-voltage ripple, so the size of the output capacitor depends largely on the maximum ESR allowed to meet the output-voltage ripple specifications as follows: RIPPLE(P P) LESV RI− = ×∆ When using low-ESR (e.g. ceramic) output capacitors, size is usually determined by the capacitance required to maintain the output voltage within specification during load transients and can be estimated as follows: OUT C IC V2 f ∆= ∆ × π× where ∆I is the load change, ∆V is the allowed voltage droop, and fC is the loop crossover frequency, which can be assumed to be the lesser of f SW/10 or 100kHz. Any calculations involving COUT should consider capacitance tolerance, temperature, and voltage derating. MAX20004/MAX20006/ MAX20008 36V, 220kHz to 2.2MHz, 4A/6A/8A Fully Integrated Automotive Step-Down Converters www.maximintegrated.com Maxim Integrated │ 13

Figure 3. Compensation Network

function is the product of the product of the modulator, compensator, and feedback transfer functions as follows: REF OUT EA EA OUT CS z_esr z_comp p_load p1_comp p2_comp VRF(s)C(s)M(s) G RVR ss11 ss s11 1 = × ×× The goal of compensation design is to reduce the loop transfer function to an approximate single-pole system with -20dB/decade gain slope and 90 degrees phase margin at the crossover frequency. To achieve this, the compensator zero is used to cancel the load pole, and the compensator high frequency pole is used to cancel the ESR zero. Assuming these cancellations, the loop transfer function reduces to the following: REF OUT OUT CS EA EA p1_comp VRF(s)C(s)M(s) VR 1GR s1 = × To derive the compensation components, the magnitude of the loop gain at the crossover frequency is set equal to 1 and solved for CC as follows (assuming the magnitude of the compensator pole at the crossover frequency is >>1): ( ) REF OUT EA EA OUT CS C EA C VR GRVR 1 12fR C × ×× ×= π× × × REF OUT EAC C OUT CS VR GC 2f V R Setting the compensator zero frequency equal to the load pole frequency and solving for R C yields: C C OUT OUT 2R C 2R C =π× × π× × OUT CS OUT CC REF EA 2C R V fR VG The above leads to an alternative equation for C C as follows: OUT OUTC C RCC R Finally, setting the high-frequency compensator pole equal to the minimum of the ESR zero frequency or 1/2 the switching frequency and solving for C F yields: SW C F ESR OUT 1 f1 Min ,2R C 2 2R C F SWC ESR OUT f12 R Min , 22 R C The above equation leads to the following compensation design procedure: 1) Select a crossover frequency equal to one tenth of the switching frequency (fSW/10) or 100kHz, which- ever is lower. 2) Calculate and select the compensation resistor, RC. 3) Calculate and select the compensation capacitor, CC. 4) Calculate and select compensation capacitor CF. 5) Evaluate the gain and phase of the final loop transfer function at the crossover frequency and adjust cross- over frequency and/or compensation as required. 6) Verify the final design with transient line/load response testing and gain-phase measurements and adjust as required. MAX20004/MAX20006/ MAX20008 36V, 220kHz to 2.2MHz, 4A/6A/8A Fully Integrated Automotive Step-Down Converters www.maximintegrated.com Maxim Integrated │ 16

Careful PCB layout is critical for stability, low-noise/ EMI and overall performance. Use a multilayer board whenever possible for better noise immunity and power dissipation. See Figure 4 for the following guidelines for good PCB layout: 1) Use the correct footprint for the IC and place as many copper planes as possible under the IC foot- print to ensure efficient heat transfer. 2) Place the ceramic input bypass capacitors (CBP and CIN) as close as possible to the SUPSW and PGND pins on the same side as the IC. Use low-impedance connections (no vias or other discontinuities) be- tween the capacitors and IC pins. CBP should be located closest to the IC and should have very good high-frequency performance (small package size, low inductance, and high. Use flexible terminations or other technologies instead of series capacitors for these functions if failure modes are a concern. This approach provides the best EMI rejection and minimizes internal noise on the device, which can degrade performance. 3) Place the inductor (L), output capacitors (COUT), boost capacitor (CBST) and BIAS capacitor (CB) on the same side as the IC in such a way as to minimize the area enclosed by the current loops. Place the inductor (L) as close as possible to the IC LX pin and minimize the area of the LX node. Place the output capacitors (COUT) near the inductor and the ground side of COUT near the CIN ground connection so as to minimize the current the loop area. Place the BIAS capacitor (CB) next to the BIAS pin. 4) Use a contiguous copper GND plane on the layer next to the IC to provide an image plane and shield the entire circuit. GND should also be poured around the entire circuit on the top side. Use a single GND: do not separate or isolate PGND and GND connec- tions with separate planes or copper areas. Ensure that all heat-dissipating components have adequate connections to copper for cooling. Use multiple vias to interconnect GND planes/areas for low impedance and maximum heat dissipation. Place vias at the GND terminals of the IC, input/output/bypass capacitors, and other components. 5) Place the compensation network (CF, CC, RC) near the COMP pin so that the ground connections are as short as possible to the GND pin. Keep high frequency signals away from these components. 6) Place the oscillator set resistor (RF) near the FSET pin so that the ground connection is as short as possible to the GND pin. Keep high-frequency signals away from this component. 7) Place the feedback resistor-divider (if used) near the IC and route the feedback and OUT connections away from the inductor and LX node and other noisy signals. MAX20004/MAX20006/ MAX20008 36V, 220kHz to 2.2MHz, 4A/6A/8A Fully Integrated Automotive Step-Down Converters www.maximintegrated.com Maxim Integrated │ 17

Figure 4. Simplified Layout Example

For variants with different options, contact factory. /V Denotes an automotive-qualified part. +Denotes a lead(Pb)-free/RoHS-compliant package. PART VOUT (FB TIED TO BIAS) VOUT (EXTERNAL RESISTOR- DIVIDER) (V) MAXIMUM OPERATING CURRENT (A) THOLD (ms) SPREAD SPECTRUM MAX20004AFOA/VY+ 5.0 4.5–10 4 0.2 Off MAX20004AFOB/VY+ 3.3 1–10 4 0.2 Off MAX20004AFOC/VY+ 5.0 4.5–10 4 0.2 On MAX20004AFOD/VY+ 3.3 1–10 4 0.2 On MAX20006AFOA/VY+ 5.0 4.5–10 6 0.2 Off MAX20006AFOB/VY+ 3.3 1–10 6 0.2 Off MAX20006AFOC/VY+ 5.0 4.5–10 6 0.2 On MAX20006AFOD/VY+ 3.3 1–10 6 0.2 On MAX20008AFOA/VY+ 5.0 4.5–10 8 0.2 Off MAX20008AFOB/VY+ 3.3 1–10 8 0.2 Off MAX20008AFOC/VY+ 5.0 4.5–10 8 0.2 On MAX20008AFOD/VY+ 3.3 1–10 8 0.2 On MAX20004/MAX20006/ MAX20008 36V, 220kHz to 2.2MHz, 4A/6A/8A Fully Integrated Automotive Step-Down Converters www.maximintegrated.com Maxim Integrated │ 19 Chip Information PROCESS: BiCMOS Ordering Information/Selector Guide

0 3/18 Initial release — 1 5/18 Removed future product status from MAX20006AFOA/VY+ and MAX20008AFOC/VY+ variants in the Ordering Information/Selector Guide table 19 2 8/18 Updated the Package Information table, and Reset Output (RESET), Setting the Output Voltage, Output Capacitor, and Compensation Network sections ; reformatted the Typical Operating Characteristics charts; replaced TOC17 and TOC18; and removed future product designation from MAX2006AFOB/ VY+, MAX2006AFOB/VY+, MAX2006AFOB/VY+, MAX2006AFOB/VY+, MAX2006AFOB/VY+, and MAX2006AFOB/VY+ 2, 5–7, 10 12–16, 19 3 11/18 Removed future product status from MAX20004AFOA/VY+, MAX20004AFOB/ VY+, MAX20004AFOC/VY+, and MAX20004AFOD/VY+ variants in the Ordering Information/Selector Guide table 4 1/19 Updated land pattern number in Package Information table 2 5 1/19 Updated thermal resistance values in Package Information table and added VOUT (external resistor-divider) column to Ordering Information/Selector Guide table 2, 19 6 2/19 Added “automotive” to product description 1–19 7 9/19 Updated Typical Application Circuit, Pin Description, and Detailed Description 1, 8, 11 8 11/19 Updated Pin Description, and Detailed Description 8, 11 Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance. Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc. © 2018 Maxim Integrated Products, Inc. │ 20 MAX20004/MAX20006/ MAX20008 36V, 220kHz to 2.2MHz, 4A/6A/8A Fully Integrated Automotive Step-Down Converters

Revision History

For pricing, delivery, and ordering information, please visit Maxim Integrated’s online storefront at https://www.maximintegrated.com/en/storefront/storefront.html.

Summary

36V, 220kHz to 2.2MHz, 4A/6A/8A Fully Integrated Automotive Step-Down Converters Rev 8; 11/19

Description