REV. 0

ADP3422

–6–

PIN FUNCTION DESCRIPTIONS

Pin No.

Mnemonic

Function

1

HYSSET

Hysteresis Set. This is an analog I/O pin whose output is a voltage reference and whose input is a

current that is programmed by an external resistance to ground. The current is used in the IC to set

the hysteretic currents for the Core Comparator and the Current Limit Comparator. Modification of the

resistance will affect both the hysteresis of the feedback regulation and the current limit set point and

hysteresis. The application circuit suggests a resistor divider, as this pin’s functionality is used to supply a

divided reference voltage to another high-impedance pin.

2

CPUSET

CPU Set. This is a high-impedance analog input pin to which a reference voltage is applied via a

resistor divider (e.g., from the HYSSET pin). The applied reference to this pin sets a threshold that

lies between two VID codes, each of which represents the Battery Optimized Mode (

BOM) VID code

of a certain CPU. At startup of the CPU regulator, the

BOM VID code is received and the corresponding

DACOUT voltage is compared against the CPUSET voltage. The type of CPU is then categorized

as being in one of two frequency categories, the lower of which has a lower

BOM VID code. The

information is latched into the IC and, if the lower frequency CPU has been detected, is used to add

a downward shift of the regulated core voltage to the optimum level. The shift is performed using the

FSHIFT and RAMP pins.

3

FSHIFT

Frequency Shift. This is an analog I/O pin whose output is a voltage reference and whose input is a

current that is programmed by an external resistance to ground. The current is used in the IC to

set a switched bias current out of the RAMP pin, depending on whether it is activated by the

latched function of the CPUSET pin. When activated, this added bias current creates a downward

shift of the regulated core voltage to a predetermined optimum level for regulation corresponding

to the frequency range of the CPU.

4

DSHIFT

Deep Sleep Shift. This is an analog I/O pin whose output is a voltage reference and whose input is a

current that is programmed by an external resistance to ground. The current is used in the IC to

set a switched bias current out of the RAMP pin, depending on whether it is activated by the

DSLP

signal. When activated, this added bias current creates a downward shift of the regulated core voltage

to a predetermined optimum level for regulation corresponding to Deep Sleep mode of CPU operation.

5

BSHIFT

Battery Optimized Mode Shift. This is an analog I/O pin whose output is a voltage reference and

whose input is a current that is programmed by an external resistance to ground. The current is

used in the IC to set a switched bias current out of the RAMP pin, depending on whether it is activated by

the

BOM signal. When activated, this added bias current creates a downward shift of the regulated core

voltage to a predetermined optimum level for regulation corresponding to Battery Optimized Mode of

CPU operation.

6

VID4

VID Input. Most significant bit.

7

VID3

VID Input

8

VID2

VID Input

9

VID1

VID Input

10

VID0

VID Input. Least significant bit.

11

BOM

Battery Optimized Mode (active low). This is a digital input pin coming from a system signal

corresponding to Battery Optimized Mode of the CPU operation in its active low state and Performance

Optimized Mode (POM) in its disactivated high state. The signal controls the optimal positioning

of the core voltage regulation level according to the functionality of the BSHIFT and RAMP pins.

It is also used to initiate a blanking period for the PWRGD signal (to disable its response to a pending

dynamic core voltage change according to the VID code) whenever a signal transition occurs.

12

DSLP

Deep Sleep Mode (active low). This is a digital input pin coming from a system signal which, in

its active state, corresponds to Deep Sleep mode of the CPU, which is a subset operating mode of

either

BOM or POM operation. The signal controls the optimal positioning of the core voltage regulation

level according to the functionality of the DSHIFT and RAMP pins.