Page 1
FEATURES
■
Programs Regulator Output Voltage Range from
1.3V to 2.05V in 50mV Steps and from 2.1V to 3.5V
in 100mV Steps (VRM 8.4)
■
Programs a Wide Range of Linear Technology
DC/DC Converters with a 0.8V Reference
■
Fully Compliant with the Intel Pentium® Processor
Desktop VID Specification
■
±0.25% Accurate Output Voltage
■
Built-In 40k Pull-Up Resistors on VID Inputs
■
Available in MSOP-10 Package
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APPLICATIO S
■
Intel Pentium II and III Processor Power Supply
■
AMD AthlonTM Processor Power Supply
■
Workstations and Servers
■
Large Memory Array Supply
LTC1706-81
5-Bit Desktop VID
Voltage Programmer
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DESCRIPTIO
The LTC®1706-81 is a precision, digitally programmed,
resistive ladder which adjusts the output of any 0.8V
referenced regulator. Depending on the state of the five
VID inputs, an output voltage between 1.3V and 3.5V is
programmed in 50mV and 100mV increments.
The LTC1706-81 is designed specifically to program
an entire family of Linear Technology DC/DC converters in
full compliance with the Intel Desktop (VRM 8.4) VID
specification.
The LTC1706-81 programs the following Linear
Technology DC/DC converter products: LTC1622,
LTC1628, LTC1629, LTC1702, LTC1735, LTC1735-1,
LTC1772 and LTC1929. (Consult factory for future compatible DC/DC converter products.)
, LTC and LT are registered trademarks of Linear Technology Corporation.
Pentium is a registered trademark of Intel Corporation.
AMD Athlon is a trademark of Advanced Micro Devices, Inc.
TYPICAL APPLICATION
5-Bit VID-Controlled High Current 4-Phase Application (Simplified Block Diagram)
V
CC
VID0
FROM
VID1
µP
VID2
VID3
VID4
SENSE
LTC1706-81
GND
FB
U
INTV
V
DIFFOUT
SGND
EAIN
SGND
EAIN
LTC1629
CC
LTC1629
V
TG1
SW1
BG1
PGND
TG2
SW2
BG2
V
TG1
SW1
BG1
PGND
TG2
SW2
BG2
IN
IN
V
IN
4.5V TO 22V
V
IN
4.5V TO 22V
L1 R
SENSE1
V
IN
R
L2
SENSE2
R
L3
SENSE3
V
IN
R
L4
SENSE4
1706-81 TA01
V
OUT
1.3V TO 3.5V
UP TO 70A
+
C
OUT
1
Page 2
LTC1706-81
1
2
3
4
5
VID0
VID1
VID2
VID3
V
CC
10
9
8
7
6
FB
GND
NC
VID4
SENSE
TOP VIEW
MS10 PACKAGE
10-LEAD PLASTIC MSOP
WW
W
ABSOLUTE MAXIMUM RATINGS
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W
PACKAGE/ORDER INFORMATION
(Note 1)
(Voltages Referred to GND Pin)
Input Supply Voltage (VCC) ..........................–0.3V to 7V
VID Input Pins .............................................– 0.3V to 7V
ORDER PART
NUMBER
LTC1706EMS-81
SENSE Pin ...................................................–0.3V to 7V
FB Pin ..........................................................–0.3V to 7V
Operating Temperature Range (Note 2) .. – 40°C to 85°C
Junction Temperature........................................... 110°C
Storage Temperature Range ................. –65°C to 150°C
T
= 110°C, θJA = 120°C/W
JMAX
MS10
PART MARKING
LTLR
Lead Temperature (Soldering, 10 sec).................. 300°C
Consult factory for Industrial and Military grade parts.
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C.
2.7V ≤ VCC ≤ 5.5V, VID0 = VID1 = VID2 = VID3 = VID4 = NC unless otherwise specified.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
CC
I
VCC
R
FB-SENSE
V
Error % Output Voltage Accuracy Programmed from 1.3V to 2.05V (VID4 = 0) ● –0.25 + 0.25 %
OUT
R
PULLUP
VID
TH
I
VID-LEAK
V
PULLUP
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The LTC1706-81 is guaranteed to meet performance specifications
from 0°C to 70°C. Specifications over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls.
Operating Supply Voltage Range 2.7 5.5 V
Supply Current (Note 3) 0.1 5 µA
Resistance Between SENSE and FB ● 12 20 28 kΩ
Programmed from 2.1V to 3.5V (VID4 = 1) ● –0.35 + 0.25 %
VID Input Pull-Up Resistance V
VID Input Voltage Threshold VIL (2.7V ≤ VCC ≤ 5.5V) 0.4 V
VID Input Leakage Current VCC < VID < 7V (Note 4) 0.01 ±1 µA
VID Pull-Up Voltage VCC = 3.3V 2.8 V
= 0.6V (Note 4) 40 kΩ
DIODE
VIH (2.7V ≤ VCC ≤ 5.5V) 1.6 V
VCC = 5V 4.5 V
Note 3: With all five VID inputs floating, the VCC supply current is simply
the device leakage current. However, the V
be approximately equal to the number of grounded VID input pins times
(VCC – 0.6V)/40k. (See the VID Input Characteristics section for more
details.)
Note 4: Each built-in pull-up resistor attached to the VID inputs also has a
series diode connected to V
supply without damage or clamping. (See Operation section for further
details.)
to allow input voltages higher than the V
CC
supply current will rise and
CC
CC
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2
Page 3
W
TEMPERATURE (°C)
–50 0 50 100
ERROR (%)
1706-81 G02
0.25
0
–0.25
V
OUT
= 2V
V
OUT
= 1.7V
V
OUT
= 1.3V
V
OUT
= 3.5V
SUPPLY VOLTAGE (V)
02468
SUPPLY CURRENT (µA)
1706-81 G06
5
4
3
2
1
0
ALL VID INPUTS OPEN
T
A
= 25°C
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TYPICAL PERFORMANCE CHARACTERISTICS
Typical Error % vs Output Voltage Typical Error % vs Temperature
0.25
TA = 25°C
0
ERROR (%)
VID4 = 0
VID4 = 1
–0.25
1.5 1.7 1.9 2.1 2.3 2.5 2.7 2.9 3.1 3.3 3.5
1.3
R
30
20
OUTPUT VOLTAGE (V)
vs Temperature I
FB1
1706-81 G01
VID-PULLUP
120
VCC = 5V
VID4 = 0V
100
VID0 = VID1 = VID2 = VID3 = OPEN
80
vs Temperature
LTC1706-81
(kΩ)
R
SUPPLY CURRENT (µA)
FB1
10
0
–50 0 50 100
TEMPERATURE (°C)
1706-81 G03
60
40
VID PULL-UP CURRENT (µA)
20
0
–50 0 50 100
TEMPERATURE (°C)
Supply Current vs Temperature Supply Current vs Supply Voltage
2.0
ALL VID INPUTS OPEN
1.5
1.0
VCC = 5V
0.5
0
–50 0 50 100
VCC = 3.3V
TEMPERATURE (°C)
VCC = 2.7V
1706-81 G05
1706-81 G04
3
Page 4
LTC1706-81
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PIN FUNCTIONS
VID0 (Pin 1): LSB Programming Input. Low = GND,
High = VCC or Float. Grounding VID0 adds 50mV
(VID4 = LOW) or 100mV (VID4 = HIGH) to the output
sense voltage.
VID1 (Pin 2): 3rd MSB Programming Input. Low = GND,
High = VCC or Float. Grounding VID1 adds 100mV
(VID4 = LOW) or 200mV (VID4 = HIGH) to the output
sense voltage.
VID2 (Pin 3): 2nd MSB Programming Input. Low = GND,
High = VCC or Float. Grounding VID2 adds 200mV
(VID4 = LOW) or 400mV (VID4 = HIGH) to the output
VCC (Pin 5): Power Supply Voltage. Range from 2.7V to
5.5V.
SENSE (Pin 6): Regulator Output Voltage. Connect
directly to regulator output sense node or, when used with
the LTC1629 and LTC1929 to V
DIFFOUT
.
VID4 (Pin 7): High-Low Output Range Programming
Input. VID4 = Low puts the output voltage in the lower
range of 1.3V to 2.05V in 50mV steps. VID4 = HIGH puts
the output voltage in the upper range of 2.1V to 3.5V in
100mV steps.
NC (Pin 8): No Connect.
sense voltage.
GND (Pin 9): Ground. Connect to regulator signal ground.
VID3 (Pin 4): MSB Programming Input. Low = GND,
High = VCC or Float. Grounding VID3 adds 400mV
(VID4 = LOW) or 800mV (VID4 = HIGH) to the output
sense voltage.
PIN NAME DESCRIPTION MIN TYP MAX MIN MAX
1 VID0 LSB Programmable Input 0 V
2 VID1 3rd MSB Programmable Input 0 V
3 VID2 2nd MSB Programmable Input 0 V
4 VID3 1st MSB Programmable Input 0 V
5V
6 SENSE Regulator Output Voltage 1.3 3.5 –0.3 7
7 VID4 Output Range Programmable Input 0 V
8NC
9 GND Ground 0 –0.3 7
10 FB 0.8V Feedback Input 0 0.8 1.5 – 0.3 7
CC
Power Supply 2.7 5.5 –0.3 7
FB (Pin 10): Feedback Input. Connect to the 0.8V feedback
pin of a compatible regulator or the EAIN pin of the
LTC1629 and LTC1929.
NOMINAL (V) ABSOLUTE MAX (V)
CC
CC
CC
CC
CC
–0.3 7
–0.3 7
–0.3 7
–0.3 7
–0.3 7
4
Page 5
BLOCK DIAGRA
V
CC
40k
VID0
1
V
CC
40k
VID1
2
V
CC
40k
VID2
3
V
CC
W
LTC1706-81
V
CC
5
6
SENSE
R
FB1
10
FB
SWITCH
CONTROL
LOGIC
V
CC
R
FB2
9
GND
1706-81 BD
VID3
40k
4
VID4
7
40k
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OPERATIO
The LTC1706-81 is a precision resistive divider designed
specifically for use with an entire family of Linear
Technology Corporation DC/DC switching regulators with
0.8V internal reference and feedback voltage. The
LTC1706-81 produces an output voltage ranging from
1.3V to 2.05V in 50mV steps and from 2.1V to 3.5V in
100mV steps by closing the loop between the output
voltage sense and the feedback input of the regulator with
the appropriate resistive divider network.
The “top” feedback resistor, R
SENSE and FB, is typically 20k and is not modified by the
state of the VID program inputs.
The “bottom” feedback resistor, R
fied by the five VID inputs and is precisely ratioed to R
, connected between
FB1
, however, is modi-
FB2
FB1
.
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. VID4 is the range
bit that puts the output voltage in either the 1.3V to 2.05V
range or the 2.1V to 3.5V range. In either range, VID3 is the
most significant bit (MSB) and VID0 is the least significant
bit (LSB).
In the lower range (VID4 = 0), when the four VID inputs are
low or grounded, the regulator output voltage is set to
2.05V. Each increasing binary count is equivalent to a
decrease of 50mV in the output voltage. Therefore, to
obtain a 1.3V output, the four VID inputs should be
floating, or high.
5
Page 6
LTC1706-81
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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 V
SENSE
.
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 minimum 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, V
DIFFOUT
, INTV
CC
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 capability 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.
6
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).
Page 7
LTC1706-81
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WUU
APPLICATIONS INFORMATION
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 inputs. This
increase in quiescent current is calculated from:
IQ = N(VCC – V
N is the number of grounded VID inputs. V
0.6V while R
PULLUP
)/R
DIODE
PULLUP
DIODE
is typically
has a typical pull-up resistance of
40kΩ.
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PACKAGE DESCRIPTION
Dimensions in inches (millimeters) unless otherwise noted.
MS10 Package
10-Lead Plastic MSOP
(LTC DWG # 05-08-1661)
In other words, each VID input has a typical pull-up current
of 68µA for a 3.3V system.
Besides the LTC1629, the LTC1706-81 also programs a
whole family of LTC DC/DC converters that have an onboard
0.8V reference. The LTC1628, LTC1735, LTC1622,
LTC1772 and LTC1929 are just a few of the high efficiency
step-down switching regulators that will work equally well
with the LTC1706-81.
0.118 ± 0.004*
(3.00 ± 0.102)
8910
7
6
3
45
0.118 ± 0.004**
(3.00 ± 0.102)
0.034 ± 0.004
(0.86 ± 0.102)
0.006 ± 0.004
(0.15 ± 0.102)
MSOP (MS10) 1098
0.193 ± 0.006
(4.90 ± 0.15)
12
0.040 ± 0.006
SEATING
PLANE
(1.02 ± 0.15)
0.009
(0.228)
REF
0.0197
(0.50)
BSC
0.007
(0.18)
0.021 ± 0.006
(0.53 ± 0.015)
* DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH,
PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
0° – 6° TYP
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
7
Page 8
LTC1706-81
TYPICAL APPLICATION
OPTIONAL SYNC
CLOCK IN
5
V
VID0
VID1
VID2
VID3
VID4
CC
SENSE
LTC1706-81
GND
9
6
10
FB
FROM
1
2
3
µP
4
7
U
VID Controlled High Current 70A 4-Phase Application
0.33µF
47k
24k
0.33µF
100pF
75k
1000pF
6800pF
1000pF
10
11
12
13
14
1
2
3
4
5
6
7
8
9
RUN/SS
SENSE1
SENSE1
EAIN
PLLFLTR
PLLIN
PHASMD
I
TH
SGND
V
DIFFOUT
–
V
OS
+
V
OS
SENSE2
SENSE2
+
–
LTC1629
–
+
CLKOUT
TG1
SW1
BOOST1
BG1
EXTV
INTV
PGND
BG2
BOOST2
SW2
TG2
AMPMD
28
5V
27
26
0.47µF
25
24
V
IN
23
22
CC
CC
D7
21
D8
20
19
18
0.47µF
17
16
15
1µF
1µF
25V
10Ω
+
22µF
6.3V
M1
150µF, 16V
× 2
+
M4
GND
L1
0.003Ω
D1
MBRS
M2
M5
L2
340T3
M3
+
V
OUT
OUT
1.3V TO
3.5V
70A
C
470µF, 6.3V
× 3
D2
MBRS
340T3
M6
0.003Ω
GND
M8
M11
L3
0.003Ω
D3
MBRS
340T3
M9
C
OUT
470µF, 6.3V
× 3
+
V
IN
12V
D4
MBRS
M12
340T3
0.003Ω
L4
1706-81 TA02
M1 TO M12: FDS7760A
L1 TO L4: 1µH SUMIDA CEPH149-IROMC
D7 TO D10: CENTROI CMDSH-3TR
: KEMET T510X477M006AS
C
OUT
: 200kHz
f
SW
47pF
0.01µF
47k
10k
100pF
1000pF
6800pF
1000pF
1
RUN/SS
2
+
SENSE1
3
–
SENSE1
4
EAIN
5
PLLFLTR
6
PLLIN
7
PHASMD
8
LTC1629
I
TH
9
SGND
10
V
NC
DIFFOUT
11
–
V
OS
12
+
V
OS
13
–
SENSE2
14
+
SENSE2
CLKOUT
TG1
SW1
BOOST1
BG1
EXTV
INTV
PGND
BG2
BOOST2
SW2
TG2
AMPMD
28
5V
27
26
25
24
V
IN
23
22
CC
21
CC
20
19
18
17
16
15
0.47µF
D9
D10
0.47µF
1µF
1µF
25V
22µF
6.3V
M7
150µF, 16V
× 2
+
M10
10Ω
+
RELATED PARTS
PART NUMBER DESCRIPTION COMMENTS
LTC1622 Low Voltage Step-Down Controller 8-Pin MSOP, 2V ≤ VIN ≤ 10V, 550kHz, Burst ModeTM Operation
LTC1628 Dual High Efficiency, 2-Phase Synchronous Step-Down Controller Constant, Standby, 5V and 3.3V LDOs, 3.5V ≤ VIN ≤ 36V
LTC1629 PolyPhaseTM High Efficiency Step-Down DC/DC Controller Expandable Up to 12 Phases, Up to 120A, Remote Sense Diff Amp
LTC1702/LTC1703 Dual High Efficiency, 2-Phase Synchronous Step-Down Controller 550kHz, 25MHz GBW, No R
LTC1709 2-Phase Synchronous Step-Down Controller with 5-Bit VID 4V ≤ VIN ≤ 36V, PLL, 36-Pin SSOP, Current Mode Operation
LTC1735 High Efficiency Synchronous Step-Down Controller Burst Mode Operation, 16-Pin Narrow SSOP, Fault Protection,
3.5V ≤ V
≤ 36V
IN
LTC1736 High Efficiency Synchronous Step-Down Controller with 5-Bit VID GN-24, Power Good, Output Fault Protection, 3.5V ≤ VIN ≤ 36V
LTC1772 SOT-23 Low Voltage Step-Down Controller 6-Pin SOT-23, 2V ≤ VIN ≤ 10V, 550kHz, Burst Mode Operation
LTC1929 2-Phase Synchronous Step-Down Controller Current Mode Operation, I
Burst Mode, PolyPhase and No R
are trademarks of Linear Technology Corporation.
SENSE
TM
, 2.7V ≤ VIN ≤ 7V
SENSE
Up to 40A, 3.5V ≤ VIN ≤ 36V
OUT
8
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear-tech.com
170681f LT/TP 0400 4K • PRINTED IN USA
LINEAR TECHNOLOGY CORPORATION 1999
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