LTC3210-2 Datasheet, PDF (7/16 Pages) Linear Technology – MAIN/CAM LED Controllers with 32-Step Brightness Control in 3mm × 3mm QFN

LTC3210-2/LTC3210-3
PIN FUNCTIONS
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. The ENC
pin is strobed up to 7 times to decrement the internal 3-bit
DAC’s from full-scale to 1LSB. The ENM pin is strobed 31
times to decrement the 5-bit DAC from full-scale to 1LSB.
The counters will stop at 1LSB if the strobing continues.
The pin must be held high after the final desired positive
strobe edge and the data is transferred after a 150μs (typ)
delay. Holding the ENM or ENC pin low will clear the coun-
ter for the selected display and reset the LED current to
0. 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 shut down.
MLED1, MLED2, MLED3 (Pins 4, 5, 6): Outputs. MLED1
to MLED3 are the MAIN current source outputs. The LEDs
are connected between CPO (anodes) and MLED1-3 (cath-
odes). The current to each LED output is set via the ENM
input, and the programming resistor connected between
RM and GND.
MLED4 (Pin 7, LTC3210-2 Only): Output. MLED4 is the
fourth main current source output available only on the
LTC3210-2 product. The LED is connected between CPO
(anode) and MLED4 (cathode). The current to MLED4
is set via the ENM input and the programming resistor
connected between RM and GND. MLED4 tracks the LED
currents of MLED1-3.
NC (Pin 7, LTC3210-3 Only): This pin is not connected
and can be left floating or connected to ground.
RM, RC (Pins 8,9): LED Current Programming Resistor
Pins. The RM and RC pins will servo to 1.22V. Resistors
connected between each of these pins and GND are used
to set the high and low LED current levels. Connecting a
resistor 15k or less will cause the LTC3210-2/LTC3210-3
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.
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