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Technical content
Features
4.5V to 18V Input Voltage Range Internal N-Channel MOSFETs Current Mode Control Adjustable PWM Frequency Adjustable Output from 0.8V to 15V Adjustable Soft-Start Time Stable with Ceramic Output Capacitors Cycle-by-cycle Current Limit Input Under-Voltage Lockout Output Under-Voltage Protection Adjustable Current Limit : 75mA to 2580mA Meet USB Current-Limiting Requirements Reverse Input-Output Voltage Protection Built-in Soft-Start 120mΩΩΩΩΩ High-Side MOSFET Operating Range : 2.5 V to 5.5 V RoHS Compliant and Halogen Free Marking Information 1A= : Product Code YMDNN : Date Code1A=YM DNN 3A, 18V Synchronous Step-Down Converter with Adjustable Current Limited Power Switch RT7249 RLIM FB BOOT LX ROSC VOUT PGND EN_SWEnable ENEnable SW_OUT SW_OUT VIN SW_IN VIN SW_IN COMP
DS7249-02 March 2017www.richtek.com ©Copyright 2017 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Function Pin Description Pin No. Pin Name Pin Function 1 SS Soft-start time setting. SS controls the soft-start period. Connect a capacitor from SS to GND to set the soft-start period. An internal current source (6 A) charges 0.1F capacitor and sets the soft-start period to 13.5ms. If SS is floating, the SS charge current will decrease to 1/128 A and charge 30pF capacitor to set the soft-start period to 4ms.
2 COMP
Compensation node. COMP is used to compensate the regulation control loop. Connect a series RC network from COMP to GND. In some cases, an additional capacitor from COMP to GND is required. 3 ROSC Switching frequency setting.
4 RLIM
Current limit setting. Switch current limit threshold can be set by an external resistor. Current limit value is from 75mA to 2580mA. The value of 10k RLIM 210k is recommended. 5 EN_SW Enable control input for power switch.
Applications
Wireless AP/Router Set-Top-Boxes Industrial and Commercial Low Power Systems LCD Monitors and TVs Green Electronics/Appliances Point of Load Regulation of High-Performance DSPs USB Bus/Self Powered Hubs USB Peripheral Ports ACPI Power Distribution Battery Power Equipment 3G/3.5G Data Card
Ordering Information
Note : Richtek products are : RoHS compliant and compatible with the current require- ments of IPC/JEDEC J-STD-020. Suitable for use in SnPb or Pb-free soldering processes. RT7249 Package Type QW : WQFN-16L 4x4 (W-Type) Lead Plating System G : Green (Halogen Free and Pb Free) Pin Configuration WQFN-16L 4x4 (TOP VIEW) PGND VIN V5V EN SS COMP ROSC RLIM SW_OUT AGND EN_SW SW_IN BOOT LX FB 5678 1316 1415 PGND FAULT
DS7249-02 March 2017 www.richtek.com ©Copyright 2017 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Functional Block Diagram Pin No. Pin Name Pin Function 6 FAULT Active-Low Open-Drain Output. Asserted during over current, over temperature, or reverse voltage conditions. 7 AGND Analog Ground. 8 SW_OUT Power Switch Output. 9 SW_IN Power Switch Input. Supply voltage range is from 2.5V to 5.5V. 10 FB Feedback Voltage Input. This pin is connected to the converter output. It is used to set the output of the converter to regulate the desired value via an resistive divider. 11 LX Switch Node. Output of the internal high-side MOSFET. Connect this pin to external low-side N-MOSFET, inductor and bootstrap capacitor. 12 BOOT Bootstrap Supply for High-Side Gate Driver. Connect a 1 F ceramic capacitor between the BOOT and LX pins. 13, 17 (Exposed Pad) PGND Power Ground. The exposed pad must be soldered to a large PCB and connected to PGND for maximum thermal dissipation. 14 VIN Power Input. Supply voltage range is from 4.5V to 18V. Must bypass with a suitable large ceramic capacitor. 15 V5V BG Driver Bias Supply. Decouple with a 1 F X5R/X7R ceramic capacitor between the V5V and GND pins. 16 EN Enable Control Input for Buck Converter. A logic-high enables the converter; a logic-low forces the device into shutdown mode. VA+ UV Comparator Oscillator Foldback Control 0.4V Internal Regulator 1.7V Shutdown Comparator Current Sense Amplifier BOOT VIN PGND LX FB EN COMP VA VCC Slope Comp Current Comparator 0.8V Control SS 1.2V Lockout Comparator +EA SS Control ROSC 10ms Deglitch 5ms Deglitch Current Limit Thermal Sense Drive CSSW_IN Switch Well SW_OUT Reverse Voltage Comparator UVLO EN_SW FAULT AGND RLIM Current SenseV5V
DS7249-02 March 2017www.richtek.com ©Copyright 2017 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Operation Buck The RT7249 is a current-mode synchronous step-down converter with adjustable frequency from 300kHz to 1.4MHz. In normal operation, the high-side N-MOSFET is turned on when the S-R latch is set by the oscillator and is turned off when the current comparator resets the S-R latch. While the high-side N-MOSFET is turned off, the low-side N-MOSFET is turned on to conduct the inductor current until next cycle begins. Switch The RT7249 has a single P-MOSFET high-side power switch with active high enable input, optimized for self- powered and bus-powered Universal Serial Bus (USB) applications. The switch's low R DS(ON) meets USB voltage drop requirements and a flag output is available to indicate fault conditions to the local USB controller. Error Amplifier The error amplifier adjusts its output voltage by comparing the feedback signal (V FB) with the internal 0.8V reference. When the load current increases, it causes a drop in the feedback voltage relative to the reference. The error amplifier's output voltage then rises to allow higher inductor current to match the load current. Oscillator The internal oscillator provides adjustable frequency from 300kHz to 1.4MHz with an external resistor. When ROSC is short to Ground, the frequency is set to 300kHz. When ROSC is floating or connected to V5V, the frequency is set to 600kHz. When ROSC is connected to a 54k Ω resistor, the frequency is set to 500kHz. Internal Regulator The regulator provides low voltage power to supply the internal control circuits and the bootstrap power for high- side gate driver. Enable The Buck converter is turned on when the EN pin is higher than 2V. When the EN pin is lower than 0.4V, the converter will enter shutdown mode and reduce the supply current to 1μA. Foldback Control When V FB is lower than 0.4V, the switching frequency will be decreased up to half of oscillation frequency. If VFB is lower than 0.2V, the switching frequency will be decreased up to 1/4 of oscillation frequency. Soft-Start (SS) An internal current source (6μA) charges an extra capacitor to build the soft-start ramp voltage (V SS). The VFB voltage will track the internal ramp voltage during soft-start interval. If SS is floating, the soft-start period is 4ms. Enable SW The switch is turned on when the EN pin is higher than 2V. When the EN pin is lower than 0.4V, the switch will enter shutdown mode. Current Limit and Short-Circuit Protection When a heavy load or short-circuit situation occurs while the switch is enabled, large transient current may flow through the device. The RT7249 includes a current limit circuitry to prevent the devices from damaging by these large current. The RT7249 provides an adjustable current limit threshold from 130mA to 2.58A (typ.) via an external resistor, R LIM, between 10kΩ and 210kΩ. However, if the RLIM pin is connected to VIN, the current limit threshold will be 75mA (typ.). Once the current limit threshold is exceeded, the device enters latch off and turns off the switch.
DS7249-02 March 2017 www.richtek.com ©Copyright 2017 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation.
Electrical Characteristics
Parameter Symbol Test Conditions Min Typ Max Unit Shutdown Current V EN = 0V -- 0.5 3 A Quiescent Current VEN = 3V, VFB = 0.9V, No load not switching -- 0.8 1.2 mA V EN = 3V, No load switching -- 7 -- Feedback Voltage V FB 4.5V VIN 18V 0.792 0.8 0.808 V Error Amplifier Transconductance GEA IC = ±10A -- 700 -- A/V Switch On-Resistance High-Side R DS(ON)1 -- 85 -- m Low-Side R DS(ON)2 -- 72 -- High-Side Switch Leakage Current V EN = 0V, VSW = 0V -- 0 10 A Switch Current Limit High-Side Min. duty cycle -- 5 -- A Low-Side From drain to source -- 1.5 -- Absolute Maximum Ratings (Note 1) Power Dissipation, PD @ TA = 25°C Package Thermal Resistance (Note 2) ESD Susceptibility (Note 3) Recommended Operating Conditions (Note 3) Switching Buck Regulator SPEC (VIN = 12V, T A = 25°C, unless otherwise specified)
DS7249-02 March 2017www.richtek.com ©Copyright 2017 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Parameter Symbol Test Conditions Min Typ Max Unit COMP to Current Sense Transconductance GCS -- 5 -- A/V Oscillation Frequency 300 -- 1400 kHz Oscillation Frequency1 f OSC1 ROSC Short to Ground 255 300 345 kHz Oscillation Frequency2 f OSC2 ROSC Float or Connect to V5V 510 600 690 kHz Oscillation Frequency3 f OSC3 ROSC Connect to R = 54k 425 500 575 kHz Oscillation Frequency4 f OSC4 ROSC Connect to R = 220k 1190 1400 1610 kHz Maximum Duty Cycle D MAX V FB = 0.7V, ROSC Short to Ground -- 93 -- % Minimum On-Time t ON_MIN -- 100 -- ns Line Regulation–DC I OUT = 2A -- 0.5 -- %/V Load Regulation–DC I OUT = 0.3A 2.7A -- 0.5 -- %/A EN Input Voltage Logic-High V IH 2 -- -- V Logic-Low V IL -- -- 0.4 Input Under-Voltage Lockout Threshold VUVLO VIN Rising 4 4.25 4.5 V VIN Falling 3.68 3.93 4.18 V VUVLO Hysteresis -- 320 -- mV V5V Voltage V5V 4.8 5 5.2 V Soft-Start Charging Current I SS -- 6 -- A Internal Soft-Start Period t SS SS Pin Open -- 4 -- ms Thermal Shutdown T SD -- 150 -- C Parameter Symbol Test Conditions Min Typ Max Unit EN_SW Input Voltage VIH 2 -- -- V VIL -- -- 0.4 Under-Voltage Lockout Threshold Rising -- 2.4 -- V Falling -- 2.2 -- V Hysteresis -- 200 -- mV Static Drain-Source On-State Resistance RDS(ON) ISW = 0.5A, SW_IN = 5V -- 90 -- ISW = 0.5A, SW_IN = 2.5V -- 125 -- Turn-On Delay Time t D_ ON SW_IN = 5V, C L = 1F, RL = 100 -- 0.66 -- ms Turn-Off Delay Time t D_OFF -- 1.6 -- ms Output Rising Time t R -- 1.1 1.5 ms Output Falling Time t F -- 1.2 1.5 ms Power Switch SPEC (VSW_IN = 3.6V, TA = 25 °C, 10kΩ ≤ RLIM ≤ 210kΩ unless otherwise specified)
DS7249-02 March 2017 www.richtek.com ©Copyright 2017 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Parameter Symbol Test Conditions Min Typ Max Unit Current-Limit Threshold and Short-Circuit Current, Out Connect to GND I OS RLIM = 10k 2420 2580 2740 mA RLIM = 15k 1595 1700 1805 RLIM = 20k 1215 1295 1375 RLIM = 49.9k 468 520 572 RLIM = 210k 110 130 150 RLIM Shorted to IN 50 75 100 Response Time to Short Circuit tIOS (Note 5) -- 2 -- s FAULT Output Low Voltage IFAULT = 1mA -- 10 -- mV FAULT Deglitch Over Current Condition -- 10 -- ms Discharge Resistance V SW_IN = 5V, EN_SW = 0V -- 100 -- Note 1. Stresses beyond those listed “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 may affect device reliability. Note 2. θ JA is measured at T A = 25 °C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. θJC is measured at the exposed pad of the package. Note 3. Devices are ESD sensitive. Handling precaution is recommended. Note 4. The device is not guaranteed to function outside its operating conditions. Note 5. Guaranteed by design.
DS7249-02 March 2017www.richtek.com ©Copyright 2017 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Typical Application Circuit RT7249 RLIM FB LX BOOT ROSC VOUT PGNDEN_SWEnable ENEnable SW_OUT SW_OUT VIN SW_IN VIN SW_IN COMP CIN 10µF CSW_IN 10µF RLIM 20k ROSC CBOOT 1µF 4.7µH COUT 22µF x 2 CFF 40.2k 7.68k 10µF13, 17 (Exposed Pad) CP 4.7nF 10kSS 1 100nF 5V/3A 6FAULT 100k V5V 15 CV5V 1µF AGND7 4.5V to 18V CSW_OUT CCOMP RCOMP CSS RFAULT NC VOUT
DS7249-02 March 2017 www.richtek.com ©Copyright 2017 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Output Voltage vs. Input Voltage 5.00 5.04 5.08 5.12 5.16 5.20 6 8 10 12 14 16 18 Input Voltage(V) Output Voltage(V) IOUT = 0A IOUT = 1A IOUT = 2A IOUT = 3A VOUT = 5V Buck Converter Typical Operating Characteristics Efficiency vs. Load Current 100 0 0.5 1 1.5 2 2.5 3 Load Current (A) Efficiency (%) VIN = 8V VIN = 12V VIN = 17V Buck Converter, VOUT = 5V Output Voltage vs. Load Current 4.90 4.95 5.00 5.05 5.10 5.15 5.20 00 . 511 . 522 . 53 Load Current (A) Output Voltage (V) VOUT = 5V Buck Converter VIN = 17V VIN = 12V VIN = 8V Reference Voltage vs. Temperature 0.790 0.795 0.800 0.805 0.810 0.815 0.820 -50 -25 0 25 50 75 100 125 Temperature (°C) Reference Voltage (V) VIN = 8V VIN = 12V VIN = 17V VOUT = 5V Buck Converter Switching Frequency vs. Output Current 610 615 620 625 630 635 640 645 650 0 0.5 1 1.5 2 2.5 3 Output Current (A) Switching Frequency (kHz) 1 VOUT = 5V, IOUT = 0A, RSOC Float Buck Converter Switching Frequency vs. Ambient Temperature 550 570 590 610 630 650 -50 -25 0 25 50 75 100 125 Ambient Temperature (°C) Switching Frequency (kHz) 1 VIN = 8V VIN = 12V VIN = 17V IOUT = 0A, RSOC Float Buck Converter
DS7249-02 March 2017www.richtek.com ©Copyright 2017 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. RDS(ON) vs. Temperature 100 120 140 160 180 200 220 240 260 280 300 -50 -25 0 25 50 75 100 125 Temperature (°C) RDS(ON) (m ) 1 VIN = 2.5V VIN = 3.3V VIN = 5V SW_IN = 2.5V to 5V Power Switch Ω Power Switching Current Limit vs. Temperature 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 -50 -25 0 25 50 75 100 125 Temperature (°C) Power Switching Current Limit (A) 1 SW_IN = 2.5V to 5V, RLIM = 20kΩ Power Switch VIN = 5V VIN = 3.3V VIN = 2.5V Power Switching Current Limit vs. RLIM 0.0 0.5 1.0 1.5 2.0 2.5 3.0 0 20 40 60 80 100 120 140 160 180 200 220 RLIM (k ) Power Switching Current Limit (mA) 1 Ω SW_IN = 5V Power Switch Switching Frequency vs. ROSC 200 400 600 800 1000 1200 1400 1600 0 20 40 60 80 100 120 140 160 180 200 220 ROSC (k ) Switching Frequency (kHz) 1 Ω VIN = 12V, VOUT = 5V, IOUT = 0A Buck Converter Fault Delay vs. Temperature -50 -25 0 25 50 75 100 125 Temperature (°C) Fault Delay (ms) VIN = 2.5V VIN = 3.3V VIN = 5V SW_IN = 2.5V to 5V Power Switch Current Limit vs. Input Voltage 456789 1 0 1 1 1 2 1 3 1 4 1 5 1 6 1 7 1 8 Input Voltage (V) Inductor Current (A) VIN = 4.5V to 17V, V OUT = 3.3V Buck Converter
DS7249-02 March 2017 www.richtek.com ©Copyright 2017 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Load Transient Response Time (250 μs/Div) IOUT (2A/Div) VOUT (200mV/Div) VIN = 12V, VOUT = 5V, IOUT = 0A to 3A Buck Converter Load Transient Response Time (250 μs/Div) IOUT (2A/Div) VOUT (100mV/Div) VIN = 12V, VOUT = 5V, IOUT = 1.5A to 3A Buck Converter Output Ripple Voltage Time (1 μs/Div) IL (2A/Div) VOUT (10mV/Div) Buck Converter, VIN = 12V, VOUT = 5V, IOUT = 3A VLX (10V/Div) Power On from V IN Time (25ms/Div) IL (2A/Div) VIN (5V/Div) VIN = 12V, VOUT = 5V, IOUT = 3A VOUT (5V/Div) Buck Converter Power Off from V IN Time (25ms/Div) IL (2A/Div) VIN (5V/Div) VIN = 12V, VOUT = 5V, IOUT = 3A VOUT (5V/Div) Buck Converter Output Ripple Voltage Time (1 μs/Div) IL (1A/Div) VOUT (10mV/Div) Buck Converter, VIN = 12V, VOUT = 5V, IOUT = 1.5A VLX (10V/Div)
DS7249-02 March 2017www.richtek.com ©Copyright 2017 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Power On from EN Time (10ms/Div) IL (2A/Div) VEN (2V/Div) Buck Converter, VIN = 12V, VOUT = 5V, IOUT = 3A VOUT (5V/Div) Power Off from EN Time (2.5ms/Div) IL (2A/Div) VEN (2V/Div) VOUT (5V/Div) Buck Converter, VIN = 12V, VOUT = 5V, IOUT = 3A Power Switching Off from SW_IN Time (100ms/Div) ISW_OUT (1A/Div) VSW_IN (2V/Div) VIN = 12V, VOUT = 5V, IOUT = 3A VSW_OUT (5V/Div) Power Switch Power Switching Current Limit Time (1ms/Div) ISW_OUT (1A/Div) VSW_IN (5V/Div) VIN = 12V, VOUT = 5V, VOUT = VSW_IN, ISW_OUT = short VSW_OUT (5V/Div) ILX (2A/Div) Power Switching On from SW_IN Time (5ms/Div) ISW_OUT (1A/Div) VSW_IN (2V/Div) VIN = 12V, VOUT = 5V, IOUT = 3A VSW_OUT (5V/Div) Power Switch Fault Time (1ms/Div) VFault (5V/Div) VSW_IN (5V/Div) VIN = 12V, VOUT = 5V, VOUT = VSW_IN, ISW_OUT = short VSW_OUT (5V/Div) ISW_OUT (2A/Div)
DS7249-02 March 2017 www.richtek.com ©Copyright 2017 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation.
Application Information
(Buck Converter) Output Voltage Setting The resistive divider allows the FB pin to sense the output voltage as shown in Figure 1. Figure 1. Output Voltage Setting where VREF is the reference voltage (0.8V typ.). boot voltage must be lower than 5.5V. Figure 2. External Bootstrap Diode
0.8 CSoft-Start time t = , if C capacitor I
Figure 3. Enable Timing Control Figure 4. Digital Enable Control Circuit EN capacitor from the VIN pin (see Figure 3).
©Copyright 2017 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. is disabled during soft-start period. Figure 5. Hiccup Mode Under-Voltage Protection large inductor to achieve this goal. approximately 20°C, the converter will resume operation. temperature should be lower than 125°C. and decreases with higher inductance. trapezoidal current at the Source of the high-side MOSFET. Table 1. Suggested Inductors for Typical
DS7249-02 March 2017 www.richtek.com ©Copyright 2017 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. OUT L OUT 1VI E S R 8fC determined by the required ESR to minimize voltage ripple. Moreover, the amount of bulk capacitance is also a key for C OUT selection to ensure that the control loop is stable. Loop stability can be checked by viewing the load transient response as described in a later section. The output ripple, ΔV OUT, is determined by : The output ripple will be the highest at the maximum input voltage since ΔIL increases with input voltage. Multiple capacitors placed in parallel may be needed to meet the ESR and RMS current handling requirement. Higher values, lower cost ceramic capacitors are now becoming available in smaller case sizes. Their high ripple current, high voltage rating and low ESR make them ideal for switching regulator applications. However, care must be taken when these capacitors are used at input and output. When a ceramic capacitor is used at the input and the power is supplied by a wall adapter through long wires, a load step at the output can induce ringing at the input, V IN. At worst, a sudden inrush of current through the long wires can potentially cause a voltage spike at V IN large enough to damage the part. Application Information (Power Switching) The RT7249 is a P-MOSFET included high-side power switch with active high enable input, optimized for self powered and bus powered Universal Serial Bus (USB) applications. The switch's low R DS(ON) meets USB voltage drop requirements and a flag output is available to indicate Fault conditions to the local USB controller. Current Limit and Short-Circuit Protection When a heavy load or short-circuit situation occurs while the switch is enabled, large transient current may flow through the device. The RT7249 includes a current limit circuitry to prevent the MOSFET switch and the hub downstream ports from damaging due to large currents. The RT7249 provides an adjustable current limit threshold between 130mA and 2.58A (typ.) via an external resistor, R LIM, between 10kΩ and 210kΩ. However, if the RLIM pin is connected to V IN, the current limit threshold will be 75mA (typ.). Once the current limit threshold is exceeded, the device enters latch mode. Fault Flag The RT7249 provides a FAULT signal pin which is an open-drain N-MOSFET output. This open-drain output goes low when current exceeds current limit threshold, VOUT − VIN exceeds reverse voltage trip level. The FAULT output is capable of sinking a 1mA load to typically 180mV above ground. The FAULT pin requires a pull-up resistor; this resistor should be large in value to reduce energy drain. A 100k Ω pull-up resistor works well for most applications. In case of an over-current condition, FAULT will be asserted only after the flag response delay time, t D, has elapsed. This ensures that FAULT is asserted upon valid over-current conditions and that erroneous error reporting is eliminated. For example, false over-current conditions may occur during hot-plug events when extremely large capacitive loads are connected, which induces a high transient inrush current that exceeds the current limit threshold. The FAULT response delay time, t D, is typically 7.5ms. Supply Filter/Bypass Capacitor A 10μF low-ESR ceramic capacitor connected from VIN to GND and located close to the device is strongly recommended to prevent input voltage drooping during hotplug events. However, higher capacitor values may be used to further reduce the voltage droop on the input. Without this bypass capacitor, an output short may cause sufficient ringing on the input (from source lead inductance) to destroy the internal control circuitry. Note that the input transient voltage must never exceed 6V as stated in the Absolute Maximum Ratings. Output Filter Capacitor A low-ESR 150μF aluminum electrolytic capacitor or 22μF ceramic capacitor connected between V OUT and GND is recommended to meet the USB standard maximum droop requirement for the hub, V BUS. Standard bypass methods should be used to minimize inductance and resistance between the bypass capacitor and the downstream connector to reduce EMI and decouple voltage droop caused by hot-insertion transients in downstream cables. Ferrite beads in series with V BUS, the ground line and the 0.1μF bypass capacitors at the power connector pins are recommended for EMI and ESD protection. The bypass
©Copyright 2017 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. on the maximum power dissipation. Figure 6. Derating Curve of Maximum Power Dissipation decoupling at higher frequencies. after the power switch input voltage is ready.
DS7249-02 March 2017 www.richtek.com Richtek Technology Corporation 14F, No. 8, Tai Yuen 1st Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5526789 Richtek products are sold by description only. Customers should obtain the latest relevant information and data sheets before p lacing orders and should verify that such information is current and complete. Richtek cannot assume responsibility for use of any circuitry other than circuit ry entirely embodied in a Richtek product. Information furnished by Richtek is believed to be accurate and reliable. However, no responsibility is assumed by Ric htek or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by i mplication or otherwise under any patent or patent rights of Richtek or its subsidiaries. Outline Dimension A D E L be SEE DETAIL A Dimensions In Millimeters Dimensions In Inches Symbol Min Max Min Max A 0.700 0.800 0.028 0.031 A1 0.000 0.050 0.000 0.002 A3 0.175 0.250 0.007 0.010 b 0.250 0.380 0.010 0.015 D 3.950 4.050 0.156 0.159 D2 2.000 2.450 0.079 0.096 E 3.950 4.050 0.156 0.159 E2 2.000 2.450 0.079 0.096 e 0.650 0.026 L 0.500 0.600 0.020 0.024 W-Type 16L QFN 4x4 Package Note : The configuration of the Pin #1 identifier is optional, but must be located within the zone indicated. DETAIL A Pin #1 ID and Tie Bar Mark Options 2 2