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1. Describe
The LM74610QDGKTQ1 is a controller device that can For reverse N-channel MOSFETs Polarity protection circuit. It is designed to drive a External MOSFET Analog Ideal Diode Rectifier when connected in series with the power supply. some kind The unique advantage of this scheme is that it does not With reference to ground, Iq is zero. LM74610-Q1 controller provides gate driver External N-Channel MOSFET and Fast Response Internal comparator discharges MOSFET gate in opposite polarity. this quick drop down Function to limit the number and duration of inversions If the opposite polarity is detected, current flows. equipment Also designed to comply with CISPR25 Class 5 EMI Specifications and Automotive ISO7637 Transient With suitable TVS diode requirements.
2. Feature
1. Compliant with automotive application requirements
2. AEC-Q100 certified with the following results:
– Exceeds HBM ESD classification level 2
– Equipment CDM ESD classification level C4B
3. 45 V maximum reverse voltage
4. No positive voltage limit on anode terminal
5. Charge pump gate driver for external N-channel MOSFETs
6. Lower power dissipation than Schottky diode/PFET solutions
7. Low reverse leakage current
8. Zero IQ
9. Fast 2µs response to reverse polarity
10. -40°C to +125°C operating ambient temperature
11. Can be used in OR-ing applications
12. Compliant with CISPR25 EMI specification
13. Meet automotive ISO7637 transient requirements with appropriate TVS diodes
14. No peak current limit
3. Application
1. ADAS
2. Infotainment system
3. Power Tools (Industrial)
4. Transmission Control Unit (TCU)
5. Battery OR-ing applications
4. Pin configuration
5. Pin Description
6. Application Information
The LM74610QDGKTQ1 is used with an N-channel MOSFET controller in a typical reverse polarity protection application. The LM74610-Q1 does not require TVS+ and TVS-. However, they are commonly used to clamp them for positive voltage surges and negative voltage surges, respectively. It is recommended to use an output capacitor Cout to protect the output voltage from immediate collapse due to line disturbances.
7. Anode and Cathode Pins
The LM74610QDGKTQ1 anode and cathode pins are connected to the source and drain of the external MOSFET. The current flowing into the anode pin is 30 µA (typ). On initial power-up, the load current flows through the body diode of the external MOSFET and the voltage on the anode and cathode pins is equal to the forward diode drop (Vf). The minimum Vf value required to enable the charge pump circuit is 0.48V. Once the MOSFET is turned on, the anode and cathode pins continuously sense the voltage difference across the MOSFET to determine the magnitude and polarity of the voltage across the MOSFET. When the MOSFET is on, the voltage difference between the anode and cathode pins depends on RDSON and the load current. If the voltage difference between the source and drain of the external MOSFET becomes negative, the anode and cathode pins will detect a fault condition and the gate pull-down pin will turn off the gate. Reverse voltage thresholds on anode and cathode detect fault conditions at -20 mV. Consistent sensing of the voltage polarity across the MOSFET enables the LM74610-Q1 to provide a fast response to power failures and limit the amount and duration of reverse current.
8. VcapH and VcapL pins
VcapH and VcapL are the high and low voltage thresholds, respectively, used by the LM74610QDGKTQ1 to detect when the charge pump circuit is turned on and off. Capacitor charge and discharge times may be related to the duty cycle of the MOSFET gate. During time period T0, the capacitor stores energy from the charge pump. During this time, the MOSFET is turned off and current flows only through the body diode. The conduction time through the MOSFET's body diode is very short (2% typical), which rules out the possibility of the MOSFET overheating, regardless of the output current. Once the capacitor voltage reaches its high threshold, the MOSFET is turned on and the charge pump circuit is disabled until Vcap reaches its low voltage threshold (T1) again. The difference between the high and low thresholds of the voltage Vcap is typically 1.15V. The LM74610-Q1 charge pump has a charge capability of 46µA at 5-8MHz.
9. Gate drive pin
The gate drive pin provides a drive current of 6.8 µA (typ) when the charge pump capacitor is charged to a high voltage level of 6.3 V (typ). When the charge pump capacitor reaches the lower voltage threshold of 5.15 V (typ), the gate is pulled down to the anode voltage (Vin). During normal operation, the gate is turned on and off at a slow slew rate of 2 ms to avoid switching noise and EMI issues. To protect the gate of the MOSFET, a built-in internal 11.5V Zener diode clamps the maximum gate-to-source voltage (VGS(MAX)).
