ADP1650

Rev. C | Page 16 of 32

initial peak as the junction temperature of the LED stabilizes.

An LED temperature vs. flash time profile for the handset PCB

design can be generated during the design phase by varying the

FL_TIM bits from the lowest to the highest setting and collecting a

Write ADC_EN = 10 to begin a die temperature measurement.

The value can be read back from the ADC_VAL[5:2] bits 1 ms

after the conversion has started. The most stable and accurate

value of die temperature is available at the end of the flash pulse.

External Voltage Mode

LED CURRENT

REG 0x02, FL_TIM = XXXX ms

REG 0x03, I_FL = XXXXX mA

REG 0x04, OUTPUT_EN = 1

STR_LV = 0

LED_MOD = 11

0A

I(FLASH)

STROBE

FL_TIM

START CONVERSION

(INTERNAL SIGNAL)

ADC_VAL[5:2]

AVAILABLE FOR READ

REG 0x08, ADC_EN = 01

The ADC measures the voltage on the GPIO2 pin when the

GPIO2 is configured as an ADC input by setting IO2_CFG =

11. One example is using an external temperature-dependent

resistor to create a voltage based on the temperature of the flash

LED. The EN line can be used for biasing to reduce leakage

current when the flash is not being used.

5 V OUTPUT OPERATION

The ADP1650 can be used as a 5 V boost to supply up to 500 mA

for an audio voltage rail or keypad LED driver voltage. To move

into voltage regulation mode, the OUTPUT_EN bit must be set

to 0. To enable the 5 V output, set LED_MOD[1:0] = 01, and set

OUTPUT_EN = 1. The ADP1650 sets the VOUT pin to 5 V

and disconnects VOUT from LED_OUT. The VOUT pin is

connected to the SW node when the ADP1650 is not enabled.

VOUT should not be connected directly to a positive external

voltage source because this causes current to flow from VOUT

to the battery.

Die Temperature Mode

The ADC measures the IC die temperature and provides the

of the flash system to optimize PCB layout for the best thermal

design.

ADP1650

10µF

1.0µH

INPUT VOLTAGE = 2.7V TO 5.0V

PGND

SW

STROBE

10µF

LED_OUT

EN

SGND

SCL

SDA

GPIO1

GPIO2

OFF

ON

SDA, SCL

EN

APPLICATIONS PROCESSOR

3.2 MEGAPIXEL

TO 5.0 MEGAPIXEL

CMOS IMAGE SENSOR

POWER-ON RESET

VOUT = 5.0V

KEYPAD

LED DRIVER

VDD

GND

VOUT*

VIN

*THE VOUT PIN IS CONNECTED TO THE SW NODE WHEN THE ADP1650 IS NOT ENABLED. VOUT SHOULD NOT BE CONNECTED DIRECTLY TO A POSITIVE

EXTERNAL VOLTAGE SOURCE BECAUSE THIS WILL CAUSE CURRENT TO FLOW FROM VOUT TO THE BATTERY.

Figure 40. ADP1650 Voltage Regulation Mode: LED Driver Application