LTC1706-82 View Datasheet(PDF) - Linear Technology

Part Name

Description

Manufacturer

LTC1706-82

VID Voltage Programmer for Intel VRM9.0/9.1

Linear Technology 

LTC1706-82

U

OPERATIO

Each VID input pin is pulled up by a 40k resistor in series

with a diode connected to VCC. Therefore, it should be

grounded (or driven low) to produce a digital low input. It

can be either floated or connected to VCC to get a digital high

input. The series diode is included to prevent the input from

being damaged or clamped when it is driven higher than VCC.

Voltage Sensing and Feedback Pins

The FB pin is a high impedance node that requires mini-

mum layout distance to reduce extra loading and un-

wanted stray pickup.

When used with the LTC1629, the LTC1706-82’s FB,

SENSE, VCC and GND pins should be connected, respec-

tively, with the EAIN, VDIFFOUT, INTVCC, and SGND pins of

the LTC1629. The result of this application is a precisely

controlled, multiphase, variable output voltage supply to

any low voltage, high current system such as a powerful

personal computer, workstation or network server. True

remote sense capability of the LTC1629 is also retained in

this case.

VID Input Characteristics

The VID inputs should be driven with a maximum VIL of

0.4V and a minimum VIH of 1.6V. However, the VID input

range is not limited to values less than VCC. Because of the

internal diode between VCC and the pull-up resistor, the

inputs can go higher than VCC without being clamped to

VCC or damaging the input.

This allows the LTC1706-82 to be fully logic compatible

and operational over a higher input voltage range (less

than the 7V absolute maximum rating).

When a VID input is grounded, there will be a higher

quiescent current flow from Vcc because of a resistor from

Vcc through a series diode to each one of the VID inputs.

This increase in quiescent current is calculated from

IQ = N(VCC – VDIODE)/RPULLUP

N is the number of grounded VID inputs. VDIODE is typically

0.6V while RPULLUP has a typical pullup resistance of 40k.

In other words, each VID input has a typical pull up current

of (VCC – 0.6)/40K, which is approximately 68µA for a 3.3V

system.

6

Table 1. VID Inputs and Corresponding Output Voltage

CODE VID4 VID3 VID2 VID1 VID0 OUTPUT

00000 GND GND GND GND GND 1.850

00001 GND GND GND GND Float 1.825

00010 GND GND GND Float GND 1.800

00011 GND GND GND Float Float 1.775V

00100 GND GND Float GND GND 1.750V

00101 GND GND Float GND Float 1.725V

00110 GND GND Float Float GND 1.700V

00111 GND GND Float Float Float 1.675V

01000 GND Float GND GND GND 1.650V

01001 GND Float GND GND Float 1.625V

01010 GND Float GND Float GND 1.600V

01011 GND Float GND Float Float 1.575V

01100 GND Float Float GND GND 1.550V

01101 GND Float Float GND Float 1.525V

01110 GND Float Float Float GND 1.500V

01111 GND Float Float Float Float 1.475V

10000 Float GND GND GND GND 1.450V

10001 Float GND GND GND Float 1.425V

10010 Float GND GND Float GND 1.400V

10011 Float GND GND Float Float 1.375V

10100 Float GND Float GND GND 1.350V

10101 Float GND Float GND Float 1.325V

10110 Float GND Float Float GND 1.300V

10111 Float GND Float Float Float 1.275V

11000 Float Float GND GND GND 1.250V

11001 Float Float GND GND Float 1.225V

11010 Float Float GND Float GND 1.200V

11011 Float Float GND Float Float 1.175V

11100 Float Float Float GND GND 1.150V

11101 Float Float Float GND Float 1.125V

11110 Float Float Float Float GND 1.100V

11111 Float Float Float Float Float NO_CPU

(1.075V)

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