Datasheet
Data Sheet ADP1649
Rev. 0 | Page 11 of 28
THEORY OF OPERATION
The ADP1649 is a high power, I
2
C programmable, white LED
driver ideal for driving white LEDs for use as a camera flash.
The ADP1649 includes a boost converter and a current regu-
lator suitable for powering one high power white LED.
WHITE LED DRIVER
The ADP1649 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 voltage,
the boost is disabled and the part operates in pass through mode.
The ADP1649 uses an integrated PFET high-side current regu-
lator for accurate brightness control.
MODES OF OPERATION
After 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.
Table 7. LED_MOD Bit Settings, I
2
C-Compatible Interface
LED_MOD
Setting Description
00
Sets the device to standby mode, consuming 3 μA
typical.
01 Sets the device to fixed VOUT = 5 V output mode.
10
Sets the device to assist light mode with continuous
LED current.
11
Sets the device to flash mode with an available
current of up to 1 A for 1.6 sec.
Figure 23. Detailed Block Diagram
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 1.0A
INTERFACE
AND
CONTROL
TxMASK1 TxMASK2
4-BIT
ADC
VIN
ILED
IO2_CFG[7:6]
IO1_CFG[5:4]
2.4V
10779-023