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PI1004 Data Sheet Rev. 2.5 Page 2 of 16

Pin Description

PIN # Pin Name

Description

1- 6

VID[0:5]

Voltage identification digital inputs. The VID inputs program the reference voltage on the REFOUT

pin. Tying all VID pins high is treated as a fault and sets the fault latch. To hardwire the VID code, the

inputs may be connected to Vcc or SGND as applicable. See Table 1 for VID codes.

7

PWRGD

Power-good open-collector output. This pin is an open circuit when (REFIN-230 mV) ≤ VO ≤ (REFIN+160

mV) and the input bus voltage is not in a UVLO condition. When VO is outside the VO window, (REFIN-

230 mV ) < VO < (REFIN+160 mV) or the input bus voltage is in a UVLO condition, or if the ENABLE is

low, the PWRGD output is low.

8

OFFSET

PI1004-1 only. Provides a programmable VID offset current. A current equal to the current out of the

OFFSET pin is added to IAVP to provide a fixed negative offset. To program the offset connect a resistor

between OFFSET and SGND. The current is nominally equal to 0.25 V / ROFFSET. Not used tie to Vcc.

8

OVP

PI1004-2 only. Over-voltage protection signal, TTL output. When VO ≥ (REFIN+220 mV) and the input

bus voltage is not in a UVLO condition and ENABLE is high, OVP is high. When VO < (REFIN+220 mV)

or the input bus voltage is in a UVLO condition, or ENABLE is low, OVP is low.

9

ENABLE

Logic input control of biasing. If ENABLE = low the PI1004 is disabled and quiescent current is reduced

to <400 uA. If ENABLE = high the PI1004 is enabled and the part operates normally if Vcc > UVLO.

10

SS

Soft start programming terminal. The error amp non-inverting input (EAIP) is clamped below the level

of the SS pin. An internal 5uA charging current is provided to program soft start with an external

capacitor. Soft start pin is discharged and held low with ENABLE low, UVLO, or VID=x11111. To control

soft-start connect a capacitor between the SS pin and SGND.

11

VO

Output voltage positive sense signal used for the power good and over-voltage protection circuits.

Connect directly to the output or if feedback divider is employed, connect to the output through a

voltage divider with the same ratio as the feedback divider.

12

ISN

Load current negative sense terminal. Connect ISN to the negative side of the sense resistor.

If AVP is not used, tie ISN to SGND.

13

ISP

Load current positive sense terminal. Connect ISP to the positive side of the sense resistor to detect

load current for AVP. If AVP is not used, tie ISP to SGND.

14

RG

Adaptive voltage positioning gain resistor connection. The sink current from the IAVP pin is:

IAVP = 4*[V(ISP)-V(ISN)]/RG. If AVP is not used, tie RG to Vcc.

15

IAVP

Adaptive voltage positioning sink current. This pin sinks current proportional to the load.

Connect to the EAIP pin with an AVP resistor (RAVP) tied from EAIP to REFOUT. The regulator

output voltage will drop with increasing load. If AVP is not used, connect IAVP to Vcc.

16

REFIN

Reference input voltage for the over-voltage protection and power good indicators.

Normally REFIN is tied to REFOUT.

17

EAIP

Non-inverting input to the error amplifier. If AVP and offset are not used, connect EAIP to

REFOUT. To use AVP connect directly to IAVP and to REFOUT through a resistor.

18

EAIN

Inverting input to the error amplifier. Connect EAIN to the positive remote output voltage sense

point through the feedback network. Run in parallel to the SGND connection to avoid noise pick-up.

19

EAO

Error amplifier output terminal.

20

REFOUT

Reference output voltage as defined by the VID codes in Table 1. The reference is capable of sourcing

up to 1 mA of current. In a typical CPU application REFOUT is connected to REFIN to set the thresholds

for Power Good and to EAIP through a resistor to enable Adaptive Voltage Positioning.

21

VCC

Internal circuit supply. Bypass Vcc to SGND with a 0.1 µF capacitor.

22

SGND

Internal substrate connection and negative output voltage sense terminal.

Connect to the negative remote output voltage sense point and run in parallel with the positive sense

line to avoid noise pick-up.

23,24

NC

No connect. Post package programming pin.