LINER LTC1706-81

LTC1706-81
5-Bit Desktop VID
Voltage Programmer
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FEATURES
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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.
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
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.)
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APPLICATIO S
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Intel Pentium II and III Processor Power Supply
AMD AthlonTM Processor Power Supply
Workstations and Servers
Large Memory Array Supply
, 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.
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TYPICAL APPLICATION
5-Bit VID-Controlled High Current 4-Phase Application (Simplified Block Diagram)
VIN
4.5V TO 22V
VIN
LTC1629
VID0
FROM
µP
INTVCC
SENSE
VID2 LTC1706-81
VID3
VID4
L1
RSENSE1
SW1
VCC
VID1
TG1
VDIFFOUT
+
BG1
VOUT
1.3V TO 3.5V
UP TO 70A
COUT
VIN
PGND
SGND
FB
TG2
EAIN
L2
RSENSE2
L3
RSENSE3
L4
RSENSE4
SW2
GND
BG2
VIN
4.5V TO 22V
VIN
LTC1629
TG1
SW1
BG1
PGND
VIN
SGND
EAIN
TG2
SW2
BG2
1706-81 TA01
1
LTC1706-81
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PACKAGE/ORDER INFORMATION
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(Note 1)
(Voltages Referred to GND Pin)
Input Supply Voltage (VCC) ..........................– 0.3V to 7V
VID Input Pins .............................................– 0.3V to 7V
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
Lead Temperature (Soldering, 10 sec).................. 300°C
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ABSOLUTE MAXIMUM RATINGS
ORDER PART
NUMBER
TOP VIEW
VID0
VID1
VID2
VID3
VCC
1
2
3
4
5
10
9
8
7
6
FB
GND
NC
VID4
SENSE
LTC1706EMS-81
MS10
PART MARKING
MS10 PACKAGE
10-LEAD PLASTIC MSOP
TJMAX = 110°C, θJA = 120°C/ W
LTLR
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
VCC
IVCC
RFB-SENSE
VOUT Error %
RPULLUP
VIDTH
IVID-LEAK
VPULLUP
PARAMETER
CONDITIONS
Operating Supply Voltage Range
Supply Current
(Note 3)
Resistance Between SENSE and FB
Output Voltage Accuracy
Programmed from 1.3V to 2.05V (VID4 = 0)
Programmed from 2.1V to 3.5V (VID4 = 1)
VID Input Pull-Up Resistance
VDIODE = 0.6V (Note 4)
VID Input Voltage Threshold
VIL (2.7V ≤ VCC ≤ 5.5V)
VIH (2.7V ≤ VCC ≤ 5.5V)
VID Input Leakage Current
VCC < VID < 7V (Note 4)
VID Pull-Up Voltage
VCC = 3.3V
VCC = 5V
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.
2
MIN
2.7
●
●
●
12
– 0.25
– 0.35
TYP
0.1
20
MAX
5.5
5
28
+ 0.25
+ 0.25
40
0.4
1.6
0.01
2.8
4.5
±1
UNITS
V
µA
kΩ
%
%
kΩ
V
V
µA
V
V
Note 3: With all five VID inputs floating, the VCC supply current is simply
the device leakage current. However, the VCC supply current will rise and
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 VCC to allow input voltages higher than the VCC
supply without damage or clamping. (See Operation section for further
details.)
LTC1706-81
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TYPICAL PERFORMANCE CHARACTERISTICS
Typical Error % vs Output Voltage
Typical Error % vs Temperature
0.25
0.25
ERROR (%)
ERROR (%)
TA = 25°C
0
VID4 = 0
VOUT = 1.3V
0
VOUT = 1.7V
VOUT = 2V
VID4 = 1
–0.25
–50
–0.25
1.3 1.5 1.7 1.9 2.1 2.3 2.5 2.7 2.9 3.1 3.3 3.5
OUTPUT VOLTAGE (V)
VOUT = 3.5V
0
50
TEMPERATURE (°C)
100
1706-81 G02
1706-81 G01
RFB1 vs Temperature
IVID-PULLUP vs Temperature
30
VID PULL-UP CURRENT (µA)
120
RFB1 (kΩ)
20
10
VCC = 5V
VID4 = 0V
VID0 = VID1 = VID2 = VID3 = OPEN
100
80
60
40
20
0
–50
0
50
TEMPERATURE (°C)
0
–50
100
0
50
TEMPERATURE (°C)
1706-81 G03
100
1706-81 G04
Supply Current vs Temperature
Supply Current vs Supply Voltage
5
2.0
ALL VID INPUTS OPEN
TA = 25°C
ALL VID INPUTS OPEN
SUPPLY CURRENT (µA)
SUPPLY CURRENT (µA)
4
1.5
1.0
VCC = 5V
VCC = 3.3V
0.5
0
–50
VCC = 2.7V
3
2
1
0
0
50
TEMPERATURE (°C)
100
1706-81 G05
0
2
4
6
SUPPLY VOLTAGE (V)
8
1706-81 G06
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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
sense voltage.
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.
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 VDIFFOUT.
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.
GND (Pin 9): Ground. Connect to regulator signal ground.
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.
ABSOLUTE MAX (V)
MIN
MAX
NAME
DESCRIPTION
1
VID0
LSB Programmable Input
0
VCC
– 0.3
7
2
VID1
3rd MSB Programmable Input
0
VCC
– 0.3
7
3
VID2
2nd MSB Programmable Input
0
VCC
– 0.3
7
4
VID3
1st MSB Programmable Input
0
VCC
– 0.3
7
5
VCC
Power Supply
2.7
5.5
– 0.3
7
1.3
3.5
– 0.3
7
0
VCC
– 0.3
7
– 0.3
7
– 0.3
7
6
SENSE
Regulator Output Voltage
7
VID4
Output Range Programmable Input
8
NC
9
GND
Ground
10
FB
0.8V Feedback Input
4
MIN
NOMINAL (V)
TYP
MAX
PIN
0
0
0.8
1.5
LTC1706-81
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BLOCK DIAGRA
VCC
40k
VID0 1
VCC
VCC
5
6
40k
VID1 2
SENSE
RFB1
VCC
10 FB
SWITCH
CONTROL
LOGIC
RFB2
9
40k
GND
VID2 3
1706-81 BD
VCC
VCC
40k
VID3 4
40k
VID4 7
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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.
VID Programming
The “top” feedback resistor, RFB1, connected between
SENSE and FB, is typically 20k and is not modified by the
state of the VID program inputs.
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.
The “bottom” feedback resistor, RFB2, however, is modified by the five VID inputs and is precisely ratioed to RFB1.
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).
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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 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 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, 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 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.
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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LTC1706-81
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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 – VDIODE)/RPULLUP
N is the number of grounded VID inputs. VDIODE is typically
0.6V while RPULLUP has a typical pull-up resistance of
40kΩ.
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PACKAGE DESCRIPTION
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.
Dimensions in inches (millimeters) unless otherwise noted.
MS10 Package
10-Lead Plastic MSOP
(LTC DWG # 05-08-1661)
0.118 ± 0.004*
(3.00 ± 0.102)
10 9 8 7 6
0.118 ± 0.004**
(3.00 ± 0.102)
0.193 ± 0.006
(4.90 ± 0.15)
1 2 3 4 5
0.040 ± 0.006
(1.02 ± 0.15)
0.007
(0.18)
0.034 ± 0.004
(0.86 ± 0.102)
0° – 6° TYP
0.021 ± 0.006
(0.53 ± 0.015)
SEATING
PLANE 0.009
(0.228)
REF
0.0197
(0.50)
BSC
0.006 ± 0.004
(0.15 ± 0.102)
MSOP (MS10) 1098
* 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
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.
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LTC1706-81
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TYPICAL APPLICATION
VID Controlled High Current 70A 4-Phase Application
OPTIONAL SYNC
CLOCK IN
0.33µF
1
SENSE1+
TG1
SENSE1–
SW1
2
3
FROM
µP
4
7
5
VCC
6
VID0
SENSE
VID1
VID2
0.33µF
6
7
100pF
8
6800pF
47k
LTC1706-81
9
10
VID3
FB
10
VID4
GND
EAIN
BOOST1
PLLFLTR
VIN
PLLIN
BG1
PHASMD
ITH
LTC1629
SGND
EXTVCC
INTVCC
PGND
VDIFFOUT
BG2
11
VOS–
BOOST2
12
VOS+
SW2
SENSE2–
TG2
SENSE2+
AMPMD
1000pF 13
9
CLKOUT
3
1000pF 4
5
RUN/SS
2
14
L1
28
27
5V
0.003Ω
26
0.47µF
25
M1
10Ω
24
M2
1µF
23
22
21
D7
20
D8
1µF
25V
+
1
22µF
6.3V
M3
150µF, 16V
×2
+
+
COUT
470µF, 6.3V
×3
GND
19
18
M4
0.47µF
17
D1
MBRS
340T3
M5
16
M6
15
VOUT
1.3V TO
3.5V
70A
D2
MBRS
340T3
0.003Ω
L2
75k
1
2
3
47pF
1000pF 4
10k
5
0.01µF
6
7
6800pF
47k
100pF
8
9
NC
10
11
12
M1 TO M12: FDS7760A
L1 TO L4: 1µH SUMIDA CEPH149-IROMC
D7 TO D10: CENTROI CMDSH-3TR
COUT: KEMET T510X477M006AS
fSW: 200kHz
1000pF 13
14
CLKOUT
RUN/SS
SENSE1+
TG1
SENSE1–
SW1
BOOST1
EAIN
VIN
PLLFLTR
BG1
PLLIN
EXTVCC
PHASMD
LTC1629
ITH
INTVCC
PGND
SGND
VDIFFOUT
BG2
VOS–
BOOST2
VOS+
SW2
SENSE2–
TG2
+
AMPMD
SENSE2
L3
28
27
5V
0.003Ω
26
25
0.47µF
10Ω
24
M7
22
21
D9
20
D10
1µF
25V
M9
M8
1µF
23
+
24k
COUT
470µF, 6.3V
×3
150µF, 16V
×2
22µF
6.3V
+
D3
MBRS
340T3
+
GND
VIN
12V
19
18
17
0.47µF
M10
M12
M11
16
15
D4
MBRS
340T3
0.003Ω
L4
1706-81 TA02
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
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8-Pin MSOP, 2V ≤ VIN ≤ 10V, 550kHz, Burst ModeTM Operation
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Constant, Standby, 5V and 3.3V LDOs, 3.5V ≤ VIN ≤ 36V
LTC1629
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550kHz, 25MHz GBW, No RSENSETM, 2.7V ≤ VIN ≤ 7V
LTC1709
2-Phase Synchronous Step-Down Controller with 5-Bit VID
4V ≤ VIN ≤ 36V, PLL, 36-Pin SSOP, Current Mode Operation
LTC1735
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Burst Mode Operation, 16-Pin Narrow SSOP, Fault Protection,
3.5V ≤ VIN ≤ 36V
LTC1736
High Efficiency Synchronous Step-Down Controller with 5-Bit VID
GN-24, Power Good, Output Fault Protection, 3.5V ≤ VIN ≤ 36V
LTC1772
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6-Pin SOT-23, 2V ≤ VIN ≤ 10V, 550kHz, Burst Mode Operation
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Current Mode Operation, IOUT Up to 40A, 3.5V ≤ VIN ≤ 36V
Burst Mode, PolyPhase and No RSENSE are trademarks of Linear Technology Corporation.
8
Linear Technology Corporation
170681f LT/TP 0400 4K • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 ● FAX: (408) 434-0507 ● www.linear-tech.com
 LINEAR TECHNOLOGY CORPORATION 1999