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PDF LTC1706I-19 Data sheet ( Hoja de datos )
| Número de pieza | LTC1706I-19 | |
| Descripción | VID Voltage Programmer | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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LTC1706-19
VID Voltage Programmer
FEATURES
s Programs Regulator Output Voltage from 1.3V to
2V in 50mV Steps
s Programs an Entire Family of Linear Technology
DC/DC Converters
s Fully Compliant with the Intel Mobile VID
Specification
s ±0.25% Accurate Output Voltage
s Built-In 40k Pull-Up Resistors on VID Inputs
s Available in SO-8 Packaging
U
APPLICATIONS
s Intel Mobile Pentium® II Processor Power Supply
s Notebook and Palmtop Computers, PDAs
s Portable Instruments
s Battery-Powered Equipment
DESCRIPTIO
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.
TYPICAL APPLICATIO
Intel Mobile Pentium II Processor Power Supply
CSS
0.1µF
COSC
47pF
1
COSC
2
RUN/SS
3
ITH
13
VIN
16
TG
CC2
220pF
CC
1000pF
RC
10k
LTC1435A
14
SW
5
SGND
12
INTVCC
50pF
6
VOSENSE
15
BOOST
+
11
BG
SENSE–
7
10
PGND
SENSE+
8
RF
4.7Ω
CF
0.1µF
VIN
4.5V TO 22V
+
M1
Si4410
CIN
10µF
30V
X2
L1
3.3µH
RSENSE
0.015Ω
*DB
0.22µF
4.7µF
M2
Si4410
D1
MBRS140T3
*CMDSH-3
1000pF
SENSE
VCC
VOUT
1.3V TO 2V
7A
FB LTC1706-19
+
COUT
820µF
4V
X2
VID
0123
GND
FROM µP
1706-19 TA01
1
1 page  
U
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, RFB1, 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, RFB2, is modified by the four VID inputs
and is precisely ratioed to RFB1.
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 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 be either 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 if it is driven higher
than VCC.
LTC1706-19
Table 1. VID Inputs and Corresponding Output Voltage
CODE
VID3 VID2 VID1 VID0
0000 GND GND GND GND
0001 GND GND GND Float
0010 GND GND Float GND
0011 GND GND Float Float
0100 GND Float GND GND
0101 GND Float GND Float
0110 GND Float Float GND
0111 GND Float GND GND
1000 Float GND GND GND
1001 Float GND GND Float
1010 Float GND Float GND
1011 Float GND Float Float
1100 Float Float GND GND
1101 Float Float GND Float
1110 Float Float 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, VCC and GND pins should be connected, respec-
tively, with the VOSENSE, VOUT, INTVCC 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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| Páginas | Total 8 Páginas | |
| PDF Descargar | [ Datasheet LTC1706I-19.PDF ] | |
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