LTC3210 Datasheet, PDF (7/16 Pages) Linear Technology – MAIN/CAM LED Controller in 3mm × 3mm QFN

LTC3210
PI FU CTIO S
C1P, C2P, C1M, C2M (Pins 1, 16, 14, 13): Charge Pump
Flying Capacitor Pins. A 2.2µF X7R or X5R ceramic ca-
pacitor should be connected from C1P to C1M and C2P
to C2M.
CPO (Pin 2): Output of the Charge Pump Used to Power
All LEDs. This pin is enabled or disabled using the ENM
and ENC inputs. A 2.2µF X5R or X7R ceramic capacitor
should be connected to ground.
ENM, ENC (Pins 3, 10): Inputs. The ENM and ENC pins
are used to program the LED output currents. Each input
is strobed up to 7 times to decrement the internal 3-bit
DACs from full-scale to 1LSB. The counter will stop at
1 LSB if the strobing continues. The pin must be held
high after the final desired positive strobe edge. The data
is transferred after a 150µs (typ) delay. Holding the ENM
or ENC pin low will set the LED current to 0 and will reset
the counter after 150µs (typ). If both inputs are held low
for longer than 150µs (typ) the part will go into shutdown.
The charge pump mode is reset to 1x whenever ENC goes
low or when the part is in shutdown mode.
MLED1, MLED2, MLED3, MLED4 (Pins 4, 5, 6, 7):
Outputs. MLED1 to MLED4 are the MAIN current source
outputs. The LEDs are connected between CPO (anodes)
and MLED1-4 (cathodes). The current to each LED output
is set via the ENM input, and the programming resistor
connected between RM and GND. Each of the four LED
outputs can be disabled by connecting the output directly
to CPO. A 10µA current will flow through each directly
connected LED output.
RM, RC (Pins 8, 9): LED Current Programming Resistor
Pins. The RM and RC pins will servo to 1.2V. Resistors
connected between each of these pins and GND are used
to set the CLED and MLED current levels. Connecting
a resistor 12k or less will cause the LTC3210 to enter
overcurrent shutdown.
CLED (Pin 11): Output. CLED is the CAM current source
output. The LED is connected between CPO (anode) and
CLED (cathode). The current to the LED output is set via
the ENC input, and the programming resistor connected
between RC and GND.
GND (Pin 12): Ground. This pin should be connected to
a low impedance ground plane.
V_BAT (Pin 15): Supply voltage. This pin should be bypassed
with a 2.2µF, or greater low ESR ceramic capacitor.
Exposed Pad (Pin 17): This pad should be connected
directly to a low impedance ground plane for optimal
thermal and electrical performance.
3210f
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