LTC3210-1_15 Datasheet, PDF (8/16 Pages) Linear Technology – MAIN/CAM LED Controller with 64-Step Brightness Control in 3mm 3mm QFN

LTC3210-1
Block Diagram
800kHz
OSCILLATOR
C1P
C1M
C2P
1
14
16
V_BAT 15
CHARGE PUMP
1.215V
RM 8
ENM 3
500Ω
250k
50ns FILTER
1.215V
500Ω
RC 9
ENC 10
250k
50ns FILTER
TIMER
6-BIT
DOWN
COUNTER
ENABLE MAIN
6-BIT
LINEAR
DAC
TIMER
TIMER
3-BIT
DOWN
COUNTER
SHUTDOWN
ENABLE CAM
3-BIT
LINEAR
DAC
C2M
13
ENABLE CP
12 GND
2 CPO
MLED
4
CURRENT
SOURCES
4 MLED1
5 MLED2
6 MLED3
7 MLED4
CLED
CURRENT
SOURCE
11 CLED
32101 BD
Operation
Power Management
The LTC3210-1 uses a switched capacitor charge pump
to boost CPO to as much as 2 times the input voltage up
to 5.1V. The part starts up in 1x mode. In this mode, V_BAT
is connected directly to CPO. This mode provides maxi-
mum efficiency and minimum noise. The LTC3210-1 will
remain in 1x mode until an LED current source drops out.
Dropout occurs when a current source voltage becomes
too low for the programmed current to be supplied. When
dropout is detected, the LTC3210-1 will switch into 1.5x
mode. The CPO voltage will then start to increase and will
attempt to reach 1.5x V_BAT up to 4.6V. Any subsequent

dropout will cause the part to enter the 2x mode. The CPO
voltage will attempt to reach 2x V_BAT up to 5.1V. The part
will be reset to 1x mode whenever the part is shut down
or when ENC goes low.
A two phase nonoverlapping clock activates the charge
pump switches. In the 2x mode the flying capacitors are
charged on alternate clock phases from V_BAT to minimize
input current ripple and CPO voltage ripple. In 1.5x mode the
flying capacitors are charged in series during the first clock
phase and stacked in parallel on V_BAT during the second
phase. This sequence of charging and discharging the flying
capacitors continues at a constant frequency of 800kHz.
32101fd