ADP1649ACBZ-R7 datasheet(13/28 Pages) AD

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Data Sheet

ADP1649

Rev. 0 | Page 13 of 28

TORCH TO FLASH MODE

The driver can move directly from external torch mode (using

GPIO1) to flash mode by bringing the STROBE pin high before

bringing the GPIO1 pin (set for the torch mode) low. Bringing

torch low before the STROBE pin goes high prevents the flash

from firing when the STROBE pin goes high.

The ADP1649 returns to standby mode after a successful flash

and sets OUTPUT_EN = 0.

Figure 29. Enabling Flash Mode from External Torch Mode

TxMASK OPERATION

When the ADP1649 is in flash mode, the TxMASK1 and the

TxMASK2 functions reduce the battery load in response to the

system enabling a power amplifier. The device remains in flash

mode, but the LED driver output current reduces to the pro-

grammed TxMASK light level in less than 21 µs.

Figure 30. TxMASK1 Operation During Flash (Level Sensitive) Mode

The device selects the TxMASK1 or TxMASK2 current level

based on whether the TxMASK1 or TxMASK2 input is used.

Anytime TxMASK1 or TxMASK2 is brought high during a

flash event, a flag is set in the fault information register. To avoid

overshoots on the battery current, when the TxMASK signal goes

low again, the LED current returns to the full flash level in a

controlled manner. If both TxMASK inputs are set high

simultaneously, the TxMASK1 current level is used.

FREQUENCY FOLDBACK

Frequency foldback is an optional mode that optimizes efficiency

by reducing the switching frequency to 1.5 MHz when VIN is

slightly less than VOUT. Enable frequency foldback by setting

FREQ_FB = 1 in Register 0x04.

INDICATOR LED DRIVER

The indicator LED driver on GPIO2 provides a programmable

current source of between 2.75 mA and 11 mA for driving a red

privacy LED; the I_ILED bits in Register 0x07 program the current

level. The circuit consists of a programmable current source and

a monitoring circuit that uses comparators to determine whether

the indicator LED is short circuit or open circuit. The threshold

for detection of a short circuit is 1.2 V (maximum), and for an

open circuit, the threshold is 2.45 V (minimum). The indicator

LED must not be used at the same time as a flash or an assist/

torch event.

LOW BATTERY LED CURRENT FOLDBACK

As the battery discharges, the lower battery voltage results in

higher peak currents through the battery ESR, which may cause

early shutdown of the phone. The ADP1649 features an optional

low battery detection option that reduces the flash current (to a

programmable level) when the battery voltage falls below a

programmable level. Set V_VB_LO = 000 to disable the low

battery current foldback (see Table 8 for details).

Figure 31. Register 0x09 Sets the Battery Voltage Threshold Level and the

Reduced LED Current Level

LED CURRENT

REG 0x02, FL_TIM = XXXX ms

IO1_CFG = 01, TORCH

REG 0x03, I_TOR = XXX mA

REG 0x03, I_FL = XXXXX mA

REG 0x04, OUTPUT_EN = 1

STR_LV = 1

LED_MOD = 00

I2C D ATA BUS

IFLASH

STROBE

ADP1649 SETS OUTPUT_EN TO 0

IASSIST

TORCH

LED CURRENT

REG 0x02, IO1_CFG = 10

FL_TIM = XXXX ms

REG 0x03, I_FL = XXXXX mA

REG 0x06, I_TX1 = XXXX mA

REG 0x04, OUTPUT_EN = 1

STR_LV = 1

LED_MOD = 11

I2C DATA BUS

IFLASH

STROBE

ADP1649 SETS OUTPUT_EN TO 0.

ADP1649 SETS LED_MOD TO 00.

ITxMASK1

TxMASK1

(GPIO1)

FL_TX1 = 1

LED CURRENT

REG 0x09, I_VB_LO = XXXX mA

V_VB_LO = XXX V

I2C DATA BUS

IFLASH

STROBE

ADP1649 SETS OUTPUT_EN TO 0.

ADP1649 SETS LED_MOD TO 00.

II_VB_LO

VIN

VV_VB_LO

REG 0x04, OUTPUT_EN = 1

LED_MOD = 10

FL_VB_LO = 1

50mV HYS

GLITCH < 50µs IGNORED

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