LTC3452 Datasheet, PDF (6/16 Pages) Linear Technology – Synchronous Buck-Boost MAIN/CAMERA White LED Driver

LTC3452
PI FU CTIO S
V_IN (Pin 1): Signal Voltage Input Supply Pin (2.7V ≤ V_IN ≤
5.5V). Recommended bypass capacitor to GND is 2.2µF
ceramic or larger. Connect to PV_IN (Pin 20).
EN_L (Pin 2): Enable Input Pin and PWM Brightness Control
for Low Power LED Bank. Active high. For constant I_MAXL
operation, connect the EN_L pin to V_IN (or any voltage
>1.2V). For EN_L voltage <0.2V, all low power bank LED
current source outputs are Hi-Z (if both EN_L and EN_H are
<0.2V, the part is in shutdown and the input supply current
drops to ~6µA). For brightness control between zero
current and I_MAXL, drive the EN_L pin with a PWM waveform
of frequency ≥10kHz. The low power LED bank currents
will be equal to a percentage of I_MAXL as given in Table 1.
The EN_L pin is high impedance and should not be floated.
I_SETL (Pin 3): Low Power LED Bank Current Programming
Pin. A resistor to ground programs each low power bank
current source output maximum to I_LEDLx|MAX = 256 •
(0.8V/R_ISETL). Enabled by EN_L (Pin 2). PWM brightness
control also via EN_L.
LED_L1 to LED_L5 (Pins 4 to 8): Individual Low Dropout
Current Source Outputs for Low Power LED Bank Current
Biasing. Connect each low power LED between V_OUT and
an individual LED_Lx pin. Unused LED_Lx outputs should be
connected to V_OUT.
GND (Pins 9 and 11): Signal Ground Pins. Connect
together and to PGND (Pin 18) and Exposed Pad ground
(Pin 21).
LED_H1, LED_H2 (Pins 10, 12): Individual Low Dropout
Current Source Outputs for High Power LED Bank Current
Biasing. Connect each high power LED between V_OUT and
an individual LED_Hx pin. Unused LED_Hx outputs should be
connected to V_OUT.
I_SETH (Pin 13): High Power LED Bank Current Program-
ming Pin. A resistor to ground programs each high power
bank current source output to I_LEDHx = 768(0.8V/R_ISETH).
Enabled by EN_H (Pin 14).
EN_H (Pin 14): Enable Input Pin for High Power LED Bank.
Active high. The EN_H pin is high impedance and should not
be floated.
V_C (Pin 15): Compensation Point for the Internal Error
Amplifier Output. Recommended compensation capacitor
to GND is 0.1µF ceramic or larger.
V_OUT (Pin 16): Buck-Boost Output Pin. Recommended
bypass capacitor to GND is 4.7µF ceramic.
SW2 (Pin 17): Switching Node Pin. Connected to internal
power switches C and D. External inductor connects
between SW1 and SW2. Recommended value is 4.7µH.
PGND (Pin 18): Power Ground Pin. Connect to GND (Pins
9 and 11).
SW1 (Pin 19): Switching Node Pin. Connected to internal
power switches A and B. External inductor connects
between SW1 and SW2. Recommended value is 4.7µH.
PV_IN (Pin 20): Power Voltage Input Supply Pin. Connect to
V_IN (Pin 1).
Exposed Pad (Pin 21): Heat Sink Ground. Connect to GND
(Pins 9 and 11) and solder to PCB ground for electrical
contact and rated thermal performance.
3452f
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