LTC3201 Linear Technology Corporation, LTC3201 Datasheet - Page 4

• Manufacturer Part Number: LTC3201
• Description: 100mA Ultralow Noise Charge Pump Led Supply
• Manufacturer: Linear Technology Corporation

LTC3201
V
ceramic capacitor to GND.
CP (Pin 2): Flying Capacitor Positive Terminal.
FILTER (Pin 3): Input Noise Filter Terminal. Bypass with a
0.22 F high resonant frequency ceramic capacitor to
GND. Place filter capacitor less than 1/8" from device.
CM (Pin 4): Flying Capacitor Negative Terminal.
GND (Pin 5): Ground. Connect to a ground plane for best
performance.
D0 (Pin 6): Current Control DAC LSB Input.
D1 (Pin 7): Current Control DAC Bit 1 Input.
D2 (Pin 8): Current Control DAC MSB Input. Inputs D0 to
D2 program a 3-bit DAC output which is used as the
SI PLIFIED
PI FU CTIO S
4
OUT
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W
U
(Pin 1): Charge Pump Output. Bypass with a 1 F
U
U
BLOCK DIAGRA
FILTER
V
OUT
V
FB
IN
10
1
3
9
LPF
W
–
+
GND
5
internal reference voltage. The DAC output reference volt-
age is used to regulate amount of current flowing through
the LEDs. An internal control loop adjusts the charge
pump output such that the voltage drop across an external
sense resistor connected from FB to GND equals the
internal DAC output reference voltage. See Truth Table in
Applications Information section for internal reference
settings vs DAC code. When D0 to D2 are low, the part
enters a low current shutdown mode and the load is
disconnected from V
V
4.5V. Bypass V
FB (Pin 10): Charge Pump Feedback Input. This pin acts
as a sense pin for I
FB and GND to set the output current. I
until V
IN
(Pin 9): Input Voltage. V
3-BIT
DAC
CHARGE
1.2V
SWITCH CONTROL
PUMP
FB
OSCILLATOR
SOFT-START
= internal DAC output reference.
1.8MHz
AND
IN
with a 1 F low ESR capacitor to ground.
3201 BD
OUT
4
8
7
6
2
IN
. Connect a sense resistor between
CP
CM
D2
D1
D0
.
IN
may be between 2.7V and
OUT
will be adjusted
3201f