Datasheet

ADP1650
Rev. C | Page 12 of 32
THEORY OF OPERATION
The ADP1650 is a high power, I
2
C programmable white LED
driver ideal for driving white LEDs for use as a camera flash.
The ADP1650 includes a boost converter and a current
regulator suitable for powering one high power white LED.
WHITE LED DRIVER
The ADP1650 drives a synchronous 3 MHz boost converter as
required to power the high power LED. If the sum of the LED
forward voltage and current regulator voltage is higher than
the battery voltage, the boost turns on. If the battery voltage is
higher than the sum of the LED V
F
and current regulator volt-
age, the boost is disabled and the part operates in pass-through
mode. The ADP1650 uses an integrated PFET high-side current
regulator for accurate brightness control.
MODES OF OPERATION
Once the enable pin is high, the device can be set into the four
modes of operation using the LED_MOD bits in Register 0x04,
via the I
2
C-compatible interface.
LED_MOD = [00] sets the device in standby mode, consuming
3 µA (typical).
LED_MOD = [01] sets the device in fixed VOUT = 5 V output
mode.
LED_MOD = [10] sets the device in assist light mode with
continuous LED current.
LED_MOD = [11] sets the device in flash mode with current up
to 1.5 A available for up to 1.6 sec.
LED_OUT PIN
PWM
CONTROLLER
PGND
PGND
VOUT
SW
PGNDSGND
VIN
UVLO
OVP
FAULT
REGISTER
IC THERMAL
SENSING
HPLED
SHORT
HPLED
DRIVER
CURRENT
SENSE
CURRENT
SENSE
SCL
STROBE
PGND
PGNDAGND
C
OUT
10µF
L1
1µF
INPUT VOLTAGE =
2.7V TO 5.0
V
C
IN
10µF
GPIO1 GPIO2
SDA
TORCH
EN
5.5V
HIGH POWER LED
CURRENT CONTROL
LED_OUT
25mA TO 1.5A
08837-006
INTERFACE
AND
CONTROL
TXMASK1 TXMASK2
4-BIT
ADC
VIN
ILED
IO2_CFG[7:6]
IO1_CFG[5:4]
2.4V
Figure 26. Detailed Block Diagram