LTC1706EMS-81 查看數據表（PDF） - Linear Technology

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LTC1706EMS-81

5-Bit Desktop VID Voltage Programmer

Linear Technology 

LTC1706-81

U

OPERATIO

Table 1. VID Inputs and Corresponding Output Voltage

CODE VID4 VID3 VID2 VID1 VID0 OUTPUT

10000 Float GND GND GND GND

3.5V

10001 Float GND GND GND Float

3.4V

10010 Float GND GND Float GND

3.3V

10011 Float GND GND Float Float

3.2V

10100 Float GND Float GND GND

3.1V

10101 Float GND Float GND Float

3.0V

10110 Float GND Float Float GND

2.9V

10111 Float GND Float Float Float

2.8V

11000 Float Float GND GND GND

2.7V

11001 Float Float GND GND Float

2.6V

11010 Float Float GND Float GND

2.5V

11011 Float Float GND Float Float

2.4V

11100 Float Float Float GND GND

2.3V

11101 Float Float Float GND Float

2.2V

11110 Float Float Float Float GND

2.1V

11111 Float Float Float Float Float

*

00000 GND GND GND GND GND 2.05V

00001 GND GND GND GND Float 2.00V

00010 GND GND GND Float GND 1.95V

00011 GND GND GND Float Float 1.90V

00100 GND GND Float GND GND 1.85V

00101 GND GND Float GND Float 1.80V

00110 GND GND Float Float GND 1.75V

00111 GND GND Float Float Float 1.70V

01000 GND Float GND GND GND 1.65V

01001 GND Float GND GND Float 1.60V

01010 GND Float GND Float GND 1.55V

01011 GND Float GND Float Float 1.50V

01100 GND Float Float GND GND 1.45V

01101 GND Float Float GND Float 1.40V

01110 GND Float Float Float GND 1.35V

01111 GND Float Float Float Float 1.30V

* Represents codes without a defined output voltage as specified in Intel

specifications. The LTC1706-81 interprets these codes as a valid input and

produces an output voltage as follows: (11111) = 2V

To program output voltages higher than 2.05V, the range

bit should be set high (VID4 = High). In this range, when

the four VID inputs are low, the output is 3.5V. Each

increasing binary count is equivalent to a decrease of

100mV in the output voltage.

When all five VID inputs are high or floating, such as when

no CPU is present in a system, a regulated 2V output is

generated at VSENSE.

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 either be 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

unwanted stray pickup.

When used with the LTC1629 or LTC1929, the

LTC1706-81’s FB, SENSE, VCC and GND pins should be

connected, respectively, with the EAIN, VDIFFOUT, INTVCC

and SGND pins of the LTC1629 and LTC1929. 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 capa-

bility is 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 LTC1706-81 to be fully logic compatible

and operational over a higher input voltage range (less

than the 7V absolute maximum rating).

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