ltc1706-61 Linear Technology Corporation, ltc1706-61 Datasheet - Page 5

• Manufacturer Part Number: ltc1706-61
• Description: 5-bit Vid Voltage Programmer For Amd Opteron Cpus
• Manufacturer: Linear Technology Corporation

OPERATIO
VID Programming
A list of programmed inputs and their corresponding
output voltages is shown in Table 1. Programming is
accomplished by applying the proper voltage (or float
condition) on the five digital VID inputs.
Table 1. VID Inputs and Corresponding Output Voltage
CODE
00000
00001
00010
00011
00100
00101
00110
00111
01000
01001
01010
01011
01100
01101
01110
01111
10000
10001
10010
10011
10100
10101
10110
10111
11000
11001
11010
11011
11100
11101
11110
11111
*Represents codes without a defined output (shutdown) voltage as
specified in AMD specifications. The LTC1706-61 interprets these codes
as a valid input and produces an output voltage as follows:
(11111) = 0.775V.
VID4
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
Float
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
VID3
GND
GND
GND
GND
GND
GND
GND
GND
Float
Float
Float
Float
Float
Float
Float
Float
GND
GND
GND
GND
GND
GND
GND
GND
Float
Float
Float
Float
Float
Float
Float
Float
U
VID2
GND
GND
GND
GND
Float
Float
Float
Float
GND
GND
GND
GND
Float
Float
Float
Float
GND
GND
GND
GND
Float
Float
Float
Float
GND
GND
GND
GND
Float
Float
Float
Float
VID1
GND
GND
Float
Float
GND
GND
Float
Float
GND
GND
Float
Float
GND
GND
Float
Float
GND
GND
Float
Float
GND
GND
Float
Float
GND
GND
Float
Float
GND
GND
Float
Float
VID0
GND
Float
GND
Float
GND
Float
GND
Float
GND
Float
GND
Float
GND
Float
GND
Float
GND
Float
GND
Float
GND
Float
GND
Float
GND
Float
GND
Float
GND
Float
GND
Float
OUTPUT
*0.775V
1.550V
1.525V
1.500V
1.475V
1.450V
1.425V
1.400V
1.375V
1.350V
1.325V
1.300V
1.275V
1.250V
1.225V
1.200V
1.175V
1.150V
1.125V
1.100V
1.075V
1.050V
1.025V
1.000V
0.975V
0.950V
0.925V
0.900V
0.875V
0.850V
0.825V
0.800V
When all five VID inputs are high or floating, such as when
no CPU is present in a system, a regulated 0.775V output
is generated at V
Each VID input pin is pulled up by a 40k resistor in series
with a diode connected to V
grounded (or driven low) to produce a digital low input. It
can either be floated or connected to V
high input. The series diode is included to prevent the
input from being damaged or clamped when it is driven
higher than V
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 LTC1629-6, the LTC1706-61’s FB,
SENSE, V
tively, with the EAIN, V
the LTC1629-6. The result of this application is a precisely
controlled, variable output voltage supply to any low
voltage, high current system such as a powerful personal
computer, workstation or network server.
VID Input Characteristics
The VID inputs should be driven with a maximum V
0.4V and a minimum V
range is not limited to values less than V
internal diode between V
inputs can go higher than V
V
This allows the LTC1706-61 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 V
V
increase in quiescent current is calculated from:
N is the number of grounded VID inputs. V
0.6V while R
40k .
CC
CC
I
Q
through a series diode to each one of the inputs. This
or damaging the input.
= N(V
CC
CC
and GND pins should be connected, respec-
PULLUP
CC
– V
.
SENSE
DIODE
has a typical pull-up resistance of
.
DIFFOUT
)/R
IH
of 1.6V. However, the VID input
CC
PULLUP
CC
and the pull-up resistor, the
CC
CC
, INTV
without being clamped to
because of a resistor from
. Therefore, it should be
LTC1706-61
CC
and SGND pins of
CC
CC
DIODE
. Because of the
to get a digital
is typically
170661f
IL
5
of