MIC45404 Datasheet, PDF (19/32 Pages) Microchip Technology – 19V 5A Ultra-Low Profile DC-to-DC Power Module

MIC45404
5.0 APPLICATION INFORMATION
5.1 Programming Start-up Delay and
External UVLO
The EN/DLY pin allows programming an external
start-up delay. In this case, the driver for the EN/DLY
pin should be an open-drain/open-collector type, as
shown in Figure 5-1.
Enable LDO
Comparator
V_IN
EN/DLY
EN_I
2 µA
EN_LDO_R
515 mV
Enable Power
Comparator
Off
C_DLY
A_GND
EN_R
1.21V
150 mV
Enable
Power
Delivery
FIGURE 5-1:
Programmable Start-up Delay Function.
The start-up delay is the delay time from the off falling
edge to the assertion of the enable power delivery
signal. It can be calculated as shown in Equation 5-1:
The EN/DLY pin can also be used to program a UVLO
threshold for power delivery by means of an external
resistor divider, as described in Figure 5-2.
EQUATION 5-1:
Where:
t_{SU_DLY}
=
E-----N----_---R-----_{-----C----D----L---Y-}
EN_I
EN_R = 1.21V
EN_I = 2 µA
C_DLY = Delay programming external capacitor
V_IN
R2
EN/DLY
R1
A_GND
Enable LDO
Comparator
EN_I
2 µA
EN_LDO_R
515 mV
Enable Power
Comparator
EN_R
1.21V
150 mV
Enable
Power
Delivery
FIGURE 5-2:
Programmable External UVLO Function.
 2015 Microchip Technology Inc.
DS20005478A-page 19