LTC1709EG Linear Technology, LTC1709EG Datasheet - Page 17

• Manufacturer Part Number: LTC1709EG
• Description: IC REG SW 2PH SYNC STPDWN 36SSOP
• Manufacturer: Linear Technology
• Type: Step-Down (Buck)r

Specifications of LTC1709EG

• Internal Switch(s): No
• Synchronous Rectifier: Yes
• Number Of Outputs: 2
• Voltage - Output: 1.3 ~ 3.5 V
• Current - Output: 3A
• Voltage - Input: 4 ~ 36 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 36-SSOP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Power - Output: -
• Frequency - Switching: -

APPLICATIO S I FOR ATIO
mon, tightly coupled pair of PC traces. The differential
amplifier corrects for DC drops in both the power and
ground paths. The differential amplifier output signal is
divided down and compared with the internal precision
0.8V voltage reference by the error amplifier.
The differential amplifier can be used in either of two
configurations according to the voltage applied to the
AMPMD pin. The first configuration with the connections
illustrated in the Functional Diagram, utilizes a set of
internal, precision resistors to enable precision instru-
mentation-type measurement of the output voltage. This
configuration is activated when the AMPMD pin is tied to
ground. When the AMPMD pin is tied to INTV
resistors are disconnected and the amplifier inputs are
made directly available. It can be used for general uses if
the amplifier is not required for true remote sensing. The
amplifier has a 0V to 3V common mode input range
limitation due to the internal switching of its inputs. The
output uses an NPN emitter follower without any internal
pull-down current. A DC resistive load to ground is re-
quired in order to sink current. The output will swing from
0V to 10V (V
Output Voltage Programming
The output voltage is digitally set to levels between 1.3V
and 3.5V using the voltage identification (VID) logic inputs
VID0 to VID4. The internal 5-bit DAC configured as a
precision resistive voltage divider sets the output voltage
in 100mV or 50mV increments according to Table 1.
The VID codes are engineered to be compatible with Intel
Pentium
output voltages from 1.3V to 3.5V.
The LSB (VID0) represents 50mV or 100mV increments
depending on the MSB. The MSB is VID4.
Between the ATTENOUT pin and ground is a variable
resistor, R1, whose value is controlled by the five VID input
pins (VID0 to VID4). Another resistor, R2, between the
ATTENIN and the ATTENOUT pins completes the resistive
divider. The output voltage is thus set by the ratio of
(R1 + R2) to R1.
Pentium is a registered trademark of Intel Corporation.
®
II and Pentium III processor specifications for
IN
V
DIFFOUT
U
U
+ 2V).
W
U
CC
, the
Table 1. VID Output Voltage Programming
* Represents codes without a defined output voltage as specified in Intel
specifications. The LTC1709 interprets these codes as a valid input and
produces an output voltage as follows: (11111) = 2V
Each VID digital input is pulled up by a 40k resistor in
series with a diode from V
grounded to get a digital low input, and can be either
VID4
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
VID3
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
VID2
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
BIAS
VID1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
. Therefore, it must be
LTC1709
VID0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
V
17
OUT
3.50V
3.40V
3.30V
3.20V
3.10V
3.00V
2.90V
2.80V
2.70V
2.60V
2.50V
2.40V
2.30V
2.20V
2.10V
2.05V
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
*
(V)