ADP1660ACBZ-R7 datasheet(10/28 Pages) AD

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ADP1660

Data Sheet

Rev. 0 | Page 10 of 28

THEORY OF OPERATION

The ADP1660 is a high power, I2C programmable, dual white

LED driver ideal for driving white LEDs for use as a camera

flash. The ADP1660 includes a boost converter and two current

regulators suitable for powering two high power white LEDs.

WHITE LED DRIVER

The ADP1660 drives a synchronous 3 MHz boost converter as

required to power the high power LEDs.

•

If the sum of the LED forward voltage plus the current

source headroom voltage is higher than the battery voltage,

the boost converter is turned on.

•

If the battery voltage is higher than the sum of the LED

forward voltage plus 2× the current source headroom

voltage, the boost converter is disabled and the part

operates in pass-through mode.

The ADP1660 uses an integrated P-FET high-side current

regulator for accurate brightness control.

The ADP1660 supports the setting of different currents for each

LED, although this configuration is not recommended. Any mis-

match in the forward voltage of the two LEDs translates directly

to lower efficiency, as well as lower accuracy of the current for the

lower voltage LED. It is recommended that the voltages on the two

LEDs be kept within 1 V of one another during operation. The

user can disable one LED and use the other LED only, if desired.

MODES OF OPERATION

When the enable pin is high, the I2C-compatible interface can

be used to set the ADP1660 to one of seven modes of operation.

These modes are configured using the LED_MOD bits (Bits[2:0])

in Register 0x01 (see Table 7).

Table 7. Modes of Operation Set by the LED_MOD Bits

LED_MOD Bits

Operating Mode

000

Standby mode, consuming 3 µA typical

(default)

001

Fixed 5 V output mode

010

Assist light mode with continuous LED current

011

Flash mode with LED currents up to 750 mA

available for up to 1.6 sec

100

Independent trigger mode with timeout

enabled (LED outputs are disabled if they are

on longer than the timer value configured by

the FL_TIM bits)

101

Independent trigger mode with timeout

disabled (FL_TIM value is ignored)

110

Fixed 5 V output mode with torch mode (total

output current must be below 500 mA)

111

Reserved

PWM

CONTROLLER

PGND

VOUT

PGND

SGND

VIN

UVLO

OVP

FAULT

IC THERMAL

SENSING

HP LED

SHORT

HP LED

DRIVER

CURRENT

SENSE

CURRENT

SENSE

SCL

STROBE

PGND

AGND

COUT

10µF

1µF

INPUT VOLTAGE = 2.7V TO 5.0V

CIN

10µF

GPIO

SDA

TORCH

5.5V

CURRENT

SENSE

HP LED

DRIVER

HIGH POWER LED

CURRENT CONTROL

LED2

UP TO

750mA

PGND

UP TO

750mA

INTERFACE

AND

CONTROL

TORCH

TxMASK

IO_CFG

2.4V

LED1

Figure 16. Detailed Block Diagram

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