LTC1706-19
VID Voltage Programmer
FEATURES
s
s
DESCRIPTIO
s
s
s
s
Programs Regulator Output Voltage from 1.3V to
2V in 50mV Steps
Programs an Entire Family of Linear Technology
DC/DC Converters
Fully Compliant with the Intel Mobile VID
Specification
±0.25%
Accurate Output Voltage
Built-In 40k Pull-Up Resistors on VID Inputs
Available in SO-8 Packaging
The LTC
®
1706-19 is a precision, digitally programmed,
resistive ladder which adjusts the output of any 1.19V
referenced regulator. Depending on the state of the four
VID inputs, an output voltage between 1.3V and 2V is
programmed in 50mV increments.
The LTC1706-19 is designed specifically to program an
entire family of Linear Technology DC/DC converters in full
compliance with the Intel Mobile VID specification.
The LTC1706-19 programs the following Linear Technol-
ogy DC/DC converter products: LTC1433, LTC1434,
LTC1435, LTC1435A, LTC1436, LTC1437, LTC1438,
LTC1439, LTC1538-AUX, LTC1539, LTC1624 and
LTC1625. (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.
APPLICATIONS
s
s
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Intel Mobile Pentium
®
II Processor Power Supply
Notebook and Palmtop Computers, PDAs
Portable Instruments
Battery-Powered Equipment
TYPICAL APPLICATIO
C
OSC
47pF
1
2
3
C
SS
0.1µF
C
OSC
RUN/SS
I
TH
LTC1435A
C
C
1000pF
C
C2
220pF
R
C
10k
50pF
Intel Mobile Pentium II Processor Power Supply
R
F
4.7Ω
V
IN
4.5V TO 22V
V
IN
TG
13
16
M1
Si4410
C
F
0.1µF
+
C
IN
10µF
30V
X2
R
SENSE
0.015Ω
V
OUT
1.3V TO 2V
7A
SW
14
L1
3.3µH
INTV
CC
5
6
SGND
V
OSENSE
BOOST
BG
PGND
SENSE
–
7
SENSE
+
8
12
*D
B
0.22µF
15
+
11
10
4.7µF
M2
Si4410
D1
MBRS140T3
1000pF
*CMDSH-3
1706-19 TA01
U
SENSE
V
CC
U
U
+
FB
LTC1706-19
C
OUT
820µF
4V
X2
VID
0 1 2 3
GND
FROM
µP
1
LTC1706-19
ABSOLUTE
(Note 1)
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
VID2 1
VID3 2
V
CC
3
GND 4
8
7
6
5
VID1
VID0
SENSE
FB
(Voltages Referred to GND Pin)
Input Supply Voltage (V
CC
) ..........................– 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
LTC1706C-19 .......................................... 0°C to 70°C
LTC1706I-19 ...................................... – 40°C to 85°C
Junction Temperature ........................................... 110°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER PART
NUMBER
LTC1706CS8-19
LTC1706IS8-19
S8 PART
MARKING
170619
706I19
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 110°C,
θ
JA
= 120°C/W
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
T
A
= 25°C, 2.7V
≤
V
CC
≤
5.5V, VID0 = VID1 = VID2 = VID3 = N. C., unless otherwise specified.
SYMBOL
V
CC
I
VCC
R
FB-SENSE
V
OUT
Error %
R
PULLUP
VID
T
I
VID-LEAK
V
PULLUP
PARAMETER
Operating Supply Voltage Range
Supply Current
Resistance Between SENSE and FB
Output Voltage Accuracy
VID Input Pull-Up Resistance
VID Input Voltage Threshold
VID Input Leakage Current
VID Pull-Up Voltage
Programmed From 1.3V to 2V
V
DIODE
= 0.6V, V
CC
= 5V, (Note 3)
V
IL
(2.7V
≤
V
CC
≤
5.5V)
V
IH
(2.7V
≤
V
CC
≤
5.5V)
V
CC
< VID < 7V, (Note 3)
V
CC
= 3.3V
V
CC
= 5V
1.6
0.01
2.8
4.5
±1
(Note 2)
q
q
CONDITIONS
MIN
2.7
TYP
0.1
MAX
5.5
5
20
0.25
UNITS
V
µA
kΩ
%
kΩ
V
V
µA
V
V
8
– 0.25
15
40
0.4
The
q
denotes specifications which apply over the full specified
temperature range.
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
With all four VID inputs floating, the V
CC
supply current is simply
the device leakage current. However, the V
CC
supply current will rise and
be approximately equal to the number of grounded VID input pins times
(V
CC
– 0.6V)/40k. (See the Typical Applications section for more detail.)
Note 3:
Each built-in pull-up resistor attached to the VID inputs also has a
series diode connected to V
CC
to allow input voltages higher than the V
CC
supply without damage or clamping. (See Operation section for further
detail.)
2
U
W
U
U
W W
W
LTC1706-19
TYPICAL PERFOR A CE CHARACTERISTICS
Typical Error % vs Output Voltage
0.25
0.25
ERROR (%)
ERROR (%)
0
–0.25
1.3
1.5
1.7
OUTPUT VOLTAGE (V)
1.9
2.0
R
FB1
vs Temperature
30
120
20
VID PULL-UP CURRENT (µA)
R
FB1
(kΩ)
10
0
–50
0
50
TEMPERATURE (°C)
Supply Current vs Temperature
2.0
5
SUPPLY CURRENT (µA)
SUPPLY CURRENT (µA)
1.5
1.0
V
CC
= 5V
0.5
V
CC
= 3.3V
0
–50
0
50
TEMPERATURE (°C)
U W
Typical Error % vs Temperature
0
V
OUT
= 1.3V
V
OUT
= 1.7V
V
OUT
= 2V
–0.25
–50
0
50
TEMPERATURE (°C)
100
1706-19 G02
1706-19 G01
I
VID-PULLUP
vs Temperature
V
CC
= 5V
100
80
60
40
20
0
–50
100
1706-19 G03
0
50
TEMPERATURE (°C)
100
1706-19 G04
Supply Current vs Supply Voltage
4
3
2
V
CC
= 2.7V
1
0
100
1706-19 G05
0
2
4
6
SUPPLY VOLTAGE (V)
8
1706-19 G06
3
LTC1706-19
PI FU CTIO S
VID2 (Pin 1):
2nd MSB Programming Input. Low = GND,
High = V
CC
or Float. Grounding VID2 adds 200mV to the
output sense voltage.
VID3 (Pin 2):
1st MSB Programming Input. Low = GND,
High = V
CC
or Float. Grounding VID3 adds 400mV to the
output sense voltage.
V
CC
(Pin 3):
Power Supply Voltage. Range from 2.7V to
5.5V.
GND (Pin 4):
Ground. Connect to regulator signal ground.
FB (Pin 5):
Feedback Input. Connect to the 1.19V feedback
pin of a compatible regulator.
SENSE (Pin 6):
Regulator Output Voltage. Connect di-
rectly to regulator output sense node.
VID0 (Pin 7):
LSB Programming Input. Low = GND,
High = V
CC
or Float. Grounding VID0 adds 50mV to the
output sense voltage.
VID1 (Pin 8):
3rd MSB Programming Input. Low = GND,
High = V
CC
or Float. Grounding VID1 adds 100mV to the
output sense voltage.
NOMINAL (V)
MIN
TYP
MAX
0
0
2.7
0
0
1.3
0
0
1.19
1.5
2
V
CC
V
CC
V
CC
V
CC
5.5
ABSOLUTE MAX (V)
MIN
MAX
– 0.3
– 0.3
– 0.3
0
– 0.3
– 0.3
– 0.3
– 0.3
7
7
7
0
7
7
7
7
PIN
1
2
3
4
5
6
7
8
NAME
VID2
VID3
V
CC
GND
FB
SENSE
VID0
VID1
BLOCK DIAGRA
4
W
U
U
U
DESCRIPTION
2nd MSB Programmable Input
1st MSB Programmable Input
Power Supply
Ground
1.19V Feedback Input
Regulator Output Voltage
LSB Programmable Input
3rd MSB Programmable Input
V
CC
V
CC
40k
VID0
V
CC
40k
VID1
V
CC
SWITCH
CONTROL
LOGIC
40k
VID2
V
CC
R
FB2
R
FB1
SENSE
FB
GND
40k
VID3
1706-19 BD
LTC1706-19
OPERATIO
The LTC1706-19 is a precision resistive divider designed
specifically for use with an entire family of Linear Technol-
ogy Corporation DC/DC switching regulators with 1.19V
internal reference and feedback voltages. The LTC1706-19
produces an output voltage ranging from 1.3V to 2V in
50mV 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
FB1
, connected between
SENSE and FB, is typically 15k and is not modified by the
state of the VID program inputs. However, the “bottom”
feedback resistor, R
FB2
, is modified by the four VID inputs
and is precisely ratioed to R
FB1
.
VID Programming
Programming is accomplished by applying the proper
voltage (or float condition) on the four digital VID inputs.
VID3 is the most significant bit (MSB), and VID0 is the
least significant bit (LSB). When all four inputs are low, or
grounded, the regulator output voltage is set to 2V. Each
increasing binary count is equivalent to a decrease of
50mv in the output voltage. Therefore, to obtain a 1.3V
output, the three MSBs are left floating, or high, while only
the LSB, VID0, is grounded. A list of programmed inputs
and their corresponding output voltages is shown in
Table 1.
When all four VID inputs are high or floating (1111), such
as when no CPU is present in a system, a regulated 1.25V
output is generated at V
SENSE
.
Each VID input pin is pulled up by a 40k resistor in series
with a diode connected to V
CC
. Therefore, it should be
grounded (or driven low) to produce a digital low input. It
can be either floated or connected to V
CC
to get a digital
high input. The series diode is included to prevent the
input from being damaged or clamped if it is driven higher
than V
CC
.
U
Table 1. VID Inputs and Corresponding Output Voltage
CODE
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
VID3
GND
GND
GND
GND
GND
GND
GND
GND
Float
Float
Float
Float
Float
Float
Float
VID2
GND
GND
GND
GND
Float
Float
Float
Float
GND
GND
GND
GND
Float
Float
Float
VID1
GND
GND
Float
Float
GND
GND
Float
GND
GND
GND
Float
Float
GND
GND
Float
VID0
GND
Float
GND
Float
GND
Float
GND
GND
GND
Float
GND
Float
GND
Float
GND
OUTPUT
2.00V
1.95V
1.90V
1.85V
1.80V
1.75V
1.70V
1.65V
1.60V
1.55V
1.50V
1.45V
1.40V
1.35V
1.30V
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 LTC1435A, the LTC1706-19’s FB,
SENSE, V
CC
and GND pins should be connected, respec-
tively, with the V
OSENSE
, V
OUT
, INTV
CC
and SGND pins of
the LTC1435A. The result of this application is a precisely
controlled variable voltage supply for any low voltage
system such as a palmtop or a laptop computer.
5
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