LTC1695
6
PIN FUNCTIONS
UUU
V
CC
(Pin 1): Power Supply Input. V
CC
supplies current to
the internal control circuitry, serves as the reference for
the 6-bit DAC and acts as the power path for the P-channel
low dropout linear regulator. Bypass V
CC
directly to ground
with a low ESR capacitor ≥10µF.
GND (Pin 2): Ground. Tie GND to the ground plane.
SCL (Pin 3): SMBus Clock Input. Data is shifted into SDA
on the rising edge of the SCL clock signal during data
transfer.
SDA (Pin 4): SMBus Bidirectional Data Input/Digital Out-
put. SDA is an open drain output and requires a pull-up
resistor or current source to V
CC
. Data is shifted into SDA
and acknowledged by SDA.
V
OUT
(Pin 5): Linear Regulator Output. Connect directly to
the fan’s +V
E
terminal. V
OUT
is set to V
ZS
(code 0) on
power-up. For good transient response and stability, use
a general purpose, low cost, medium ESR (0.1Ω to 1Ω)
tantalum or electrolytic capacitor. LTC recommends a
surface mount tantalum capacitor of ≥4.7µF.
1695 • G21
V
OUT
(AC)
20mV/DIV
I
LOAD
50mA/DIV
100µs/DIV
V
CC
= 5V
C
OUT
= 4.7µF TANTALUM
1695 • G22
V
OUT
(AC)
20mV/DIV
I
LOAD
50mA/DIV
100µs/DIV
V
CC
= 5V
C
OUT
= 4.7µF TANTALUM
1695 • G23
V
OUT
2V/DIV
100ms/DIV
V
CC
= 5V
C
IN
= 10µF
C
OUT
= 4.7µF
I
LOAD
= 1mA
TYPICAL PERFOR A CE CHARACTERISTICS
UW
Load Transient Response
Dropout (Code 63), 5mA to 55mA
Load Transient Response
Dropout (Code 63), 50mA to 100mA
Boost Start Timer
