Data Sheet

ADPL20502

analog.com

Rev 0

18 of 27

4.4

28.0

4.5

23.7

4.6

20.0

4.7

16.9

4.8

14.0

4.9

11.8

5.0

10.0

5.1

8.45

5.2

7.15

5.4*

4.99

5.5*

SHORT TO GROUND

* Indicates ULPM disabled.

Fixed-Output Voltage Version

In applications where board space is at a premium, contact a Maxim Integrated representative to order fixed-output

versions that don’t require the RSEL resistor to program the output voltage. The RSEL pin must be left floating for fixed

output versions. The output voltage can be preprogrammed in the range from 2.3V to 5.2V with 100mV resolution.

5.3V, 5.4V, and 5.5V output target levels are available. The output target levels programmed to 5.3V, 5.4V, and 5.5V

will have the ULPM disabled.

Features

Enable

The ADPL20502 includes an enable input pin (EN). Connect EN pin to IN pin or drive it to more than 0.6V (VEN_IH) for

normal operation. When EN pin goes below 0.55V (VEN_IL), ADPL20502 enters True Shutdown mode. The device will

consume 1nA (ISD_IN) of current from VIN while in this mode.

In shutdown, the output is truly disconnected from the input. In conventional boost circuits, the body diode of the

synchronous rectifier is forward biased in shutdown and allows current flow from the battery to the output. If the

load cannot be shut down, a load switch is required to avoid depleting the battery during the shutdown. A proprietary

design in the ADPL20502 allows the synchronous rectifier to provide True Shutdown with no additional components.

True Shutdown on the ADPL20502 allows the output to be biased at any voltage or grounded without consuming any

current from IN or OUT pins other than pin leakage currents.

Soft-Start Control

After the EN pin goes above its raising threshold (VEN_IH), the ADPL20502 begins the startup.

When the output capacitor is fully discharged prior to the device being enabled, the startup follows the below steps:

When VIN is at its final level, for example, 3V, the ADPL20502 ramps the output to the level where VOUT starts

approaching VIN, at which point switching is enabled. It then acquires the RSEL pin voltage level to determine the

output target level. Then, the output is ramped up to its target voltage level, for example, 5.0V following a 3V/ms slew

rate. This controls the amount of inrush current into the output capacitor.

The ADPL20502 starts with a 0.9V input voltage and a load resistance of 3kΩ or larger. Enabling the device when VIN

is between 0.9V and 2.0V will be load current limited. If the load current is heavy such that it does not allow the

ADPL20502 to charge the output above 1.5V, the device cannot reach its output target level until VIN is increased or

the load current is reduced.