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LM74700-Q1: LM74700-Q1 and lm74722-Q1

Part Number: LM74700-Q1
Other Parts Discussed in Thread: LM74720-Q1

Hi Team,

1. The lm74700 has an external single MOS, and the datasheet has a shutdown current of 1uA (EN = low level), but when the 74700 single MOS is external, even if it is turned off, the input will not be switched from the body of the 74700 external MOS. Is the diode leakage past? This 1uA indicator is somewhat incomprehensible;

2. If the off current is considered to be as small as possible, is it more appropriate to use lm74722?

3. Does the output current of the ideal diode controller only depend on the parameter Id of the external mosFET selection, and there is no requirement for the controller chip itself?

4. In the parameter table, there is an I(gate), peak sink currrent value, what is the main focus of this value?

  • Hi Amelie,

    Please see my response below,

    1. The 1uA shutdown current is the current drawn by the LM74700-Q1 IC. This is not the load current but only the current which flows out of the GND pin of the LM74700-Q1 IC. Please understand that LM74700-Q1 drive only an Ideal Diode FET and this is not capable of blocking forward current. This FET is capable of blocking reverse current.
    2. If the forward current needs to be blocked, you can consider using LM7800-Q1 or LM74720-Q1.
    3. Yes, The load current capability of the Ideal Diode controller is dependent on the FETs Rds(on) and its current capability. The only care about to consider is that. as the load current increases , lower Rds(on) FETs are used. A lower Rds(on) corresponds to higher -ve current (V(AC_REV)/Rds(on)) required to detect a reverse current and turn OFF the FET. 
    4. Peak Gate sink current is the pull down current from the Gate pin to turn OFF the FET. This parameter decides how fast the FETs are turned OFF when the Gate is pulled low.