While the reset function of the LM53600-Q1 and LM53601-Q1 devices resembles a standard power good function, its functionality is designed to replace a discrete reset IC, reducing BOM cost. There are three major differences between the reset function and the normal power good function seen in most regulators:
The following table summarizes conditions that cause a fault to be flagged by RESET . Once a fault is flagged, RESET will not be released (become high impedance) until either there is no fault for treset_act or VIN drops below Vreset_valid.
Table showing conditions that cause RESET to signal a fault (pull low).
|FAULT CONDITION INITIATED||FAULT CONDITION ENDS (AFTER WHICH Treset_act MUST PASS BEFORE RESET OUTPUT IS RELEASED)|
|FB below Vreset_UV for longer than treset_filt||FB above Vreset_UV + Vreset_hyst for longer than treset_filt|
|FB above Vreset_OV for longer than treset_filt||FB below Vreset_OV - Vreset_hyst for longer than treset_filt|
|Junction temperature exceeds TSD||Junction temperature falls below TSD – TSD_hyst|
|EN low||tEN passes after EN becomes high(1)|
|VIN falls below Vin_UVLO - Vin_UVLO _hyst or VCC pin falls below Vcc_UVLO - Vcc_UVLO_hyst||Voltage on VIN exceeds Vin_UVLO and VCC exceed Vcc_UVLO|
The threshold voltage for the RESET function is specified taking advantage of the availability of the LM53600-Q1 internal feedback threshold to the RESET circuit. This allows a maximum threshold of 97% of selected output voltage to be specified at the same time as 95.7% of actual operating point. The net result is a more accurate reset function while expanding the system allowance for transient response without the need for extremely accurate internal circuitry. See output voltage error stack up comparison, below.