ADP1650ACBZ-R7 datasheet(18/32 Pages) AD

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ADP1650

Rev. C | Page 18 of 32

SAFETY FEATURES

For critical fault conditions, such as output overvoltage, flash

timeout, LED output short circuit, and overtemperature

conditions, the ADP1650 has built-in protection modes. If a

critical fault occurs, OUTPUT_EN (Register 0x04) is set to 0,

and the driver shuts down. The appropriate fault bit is set in the

fault information register (Register 0x05). The processor can

read the fault information register through the I2C interface to

determine the nature of the fault condition. When the fault

If a noncritical event such as an indicator LED open/short or a

TxMASK1 or TxMASK2 event occurs, or the dc current limit or

soft inductor current limit is hit, the LED driver continues

operating. The corresponding information bits are set in the

fault information register until the processor reads them.

SHORT-CIRCUIT FAULT

When the flash driver is disabled, the high-side current regulator

disconnects the dc path between the battery and the LED, pro-

tecting the system from an LED short circuit. The LED_OUT

pin features short-circuit protection that monitors the LED

voltage when the LED driver is enabled. If the LED_OUT pin

remains below the short-circuit detection threshold, a short

circuit is detected. Bit 6 of the fault information register is set

high. The ADP1650 remains disabled until the processor clears

the fault register.

OVERVOLTAGE FAULT

The ADP1650 contains a comparator at the VOUT pin that

monitors the voltage between VOUT and GND. If the voltage

exceeds 5.5 V (typical), the ADP1650 shuts down. Bit 7 in the

fault information register is read back as high. The ADP1650 is

disabled until the fault is cleared, ensuring protection against an

open circuit.

DYNAMIC OVERVOLTAGE MODE (DOVP)

Dynamic OVP mode is a programmable feature that limits the

VOUT voltage exceeding the OVP level while maintaining as

much current as possible through the LED. This mode prevents

an overvoltage fault in the case of a much higher than expected

LED forward voltage. If the LED forward voltage reduces due to

the LED temperature rising, the ADP1650 moves out of DOVP

mode and regulates the LED at the programmed current level.

Set Bit 7 of Register 0x07 high to enable dynamic OVP mode.

TIMEOUT FAULT

When external strobe mode is enabled (Register 0x04, Bit 2),

and strobe is set to level-sensitive mode (Register 0x04, Bit 5),

if the strobe pin remains high for longer than the programmed

timeout period, the timeout fault bit (Register 0x05, Bit 4) is

read back as high. The ADP1650 remains disabled until the

processor clears the fault register.

OVERTEMPERATURE FAULT

If the junction temperature of the ADP1650 rises above 150°C,

a thermal protection circuit shuts down the device. Bit 5 of the

fault information register is set high. The ADP1650 remains

disabled until the processor clears the fault register.

INDICATOR LED FAULT

The GPIO2 pin features open- and short-circuit protection in

the indicator LED mode. If a short or open circuit occurs, Bit 2

of the fault information register is set high. The indicator LED

regulator ensures that no damage occurs to the IC during a fault.

CURRENT LIMIT

The internal switch limits battery current by ensuring that the

peak inductor current does not exceed the programmed limit

(current limit is set by Bit 6 and Bit 7 in Register 0x04). The

default mode of the ADP1650 is soft current limit mode. If the

peak inductor current hits the limit, Bit 1 of the fault informa-

tion register is set, and the inductor and LED current cannot

increase further. The ADP1650 continues to operate. If the

ADP1650 has soft current limit disabled and the peak inductor

current exceeds the limit, the part shuts down and Bit 1 of the

fault information register is set high. In this case, ADP1650

remains disabled until the processor clears the fault register.

INPUT UNDERVOLTAGE

The ADP1650 includes a battery undervoltage lockout circuit.

During 5 V or LED operation, if the battery voltage drops below

the 2.4 V (typical) input UVLO threshold, the ADP1650 shuts

down. A power-on reset circuit resets the registers to their

default conditions when the voltage rises above the UVLO

rising threshold.

SOFT START

The ADP1650 has a soft start mode that controls the rate of

increase of battery current at startup by digitally controlling the

output current ramp. The maximum soft start time is 0.6 ms.

RESET USING THE ENABLE (EN) PIN

A low-to-high transition on the EN pin resets all registers to

their default values. Bringing EN low reduces the IQ to 0.2 μA

(typical).

CLEARING FAULTS

The information bits and faults in Register 0x05 clear

automatically when the processor reads the fault register.

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