ADP1655-EVALZ Analog Devices Inc, ADP1655-EVALZ Datasheet - Page 19

• Manufacturer Part Number: ADP1655-EVALZ
• Description: Dual LED Flash Driver Eval. Board
• Manufacturer: Analog Devices Inc

Specifications of ADP1655-EVALZ

• Core Chip: ADP1655
• Topology: Boost
• No. Of Outputs: 2
• Dimming Control Type: PWM
• Tool / Board Applications: Analog/Mixed Signal-Clock, Timer
• Supported Devices: AD9552
• Msl: MSL 1 - Unlimited
• Current - Output / Channel: 500mA
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 4.9V
• Features: Camera Flash and Torch Modes, I²C Interface, Programmable Output Current
• Voltage - Input: 2.7 ~ 5.5 V
• Utilized Ic / Part: ADP1655
• Development Tool Type: Hardware - Eval/Demo Board
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

SAFETY FEATURES
For critical system conditions, such as output overvoltage,
flash timeout, LED output short circuit, and overtemperature
conditions, the ADP1655 has built-in safety mechanisms. If
one of the fault conditions occurs, the device shuts down and
a corresponding flag is set in the fault information register
(Register 0x05). In I
processor can read the fault information register through the
I
and, consequently, the fault flag is cleared. The device is
disabled until the fault information register is cleared.
In 2-bit logic interface mode, the I
available. To clear a fault, set EN1, EN2, and TORCH low.
OVERVOLTAGE FAULT
The ADP1655 contains a comparator at the VOUT pin that
monitors the voltage between VOUT and SGND. If the voltage
exceeds 9.5 V (typical), the ADP1655 shuts down. In I
Bit 7 in the fault information register is read back as high. The
ADP1655 is disabled until the fault is cleared, ensuring protec-
tion against an open circuit.
OUTPUT CAPACITOR FAULT
If no output capacitor is present at the VOUT pin when the
ADP1655 is enabled for a flash, torch, or assist light event,
the part shuts down and Bit 7 in the fault information register
is read back as high. The ADP1655 is disabled until the fault is
cleared. The output capacitor detection scheme does not cause
the VOUT pin to rise above the overvoltage threshold even though
the overvoltage flag (Bit 7) in the fault information register
(Register 5) is set. The overvoltage and output capacitor fault
flags share a single register bit to reduce the required number
of registers.
TIMEOUT FAULT
If the 2-bit logic interface is used, the maximum duration for
flash being enabled (EN1/EN2 = 1) is preset to 850 ms. If EN1
and EN2 remain high for longer than 850 ms, ADP1655 is
disabled until the fault is cleared (EN1, EN2, and TORCH low).
In I
strobe is set to level sensitive mode (Register 0x04, Bit 5), and
if strobe remains high for longer than 850 ms, the timeout fault
bit, Register 0x05, Bit 4), is read back as high. The ADP1655 is
disabled until the fault is cleared.
2
C interface to determine the nature of the fault condition
2
C mode, if strobe mode is enabled (Register 0x04, Bit 2),
2
C interface mode, the system baseband
2
C register readback is not
2
C mode,
Rev. 0 | Page 19 of 24
OVERTEMPERATURE FAULT
If the junction temperature of the ADP1655 rises above 150°C,
a thermal protection circuit shuts down the device. In I
Bit 5 of the fault information register is read back as high. The
ADP1655 is disabled until the fault is cleared.
SHORT-CIRCUIT FAULT
The LED_OUT pin features short-circuit protection that
disables the ADP1655 if it detects a short circuit to ground at
the LED_OUT pin. The ADP1655 monitors the LED voltage
when the LED driver is enabled. If the LED_OUT pin remains
below the short-circuit detection threshold during startup, a
short circuit is detected. Bit 6 of the fault information register
is read back as high. The ADP1655 is disabled until the fault is
cleared.
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 the output mode register,
Register 0x04). If the peak inductor current exceeds the limit,
the part shuts down and Bit 1 of the fault information register
is read back as high. The ADP1655 is disabled until the fault is
cleared.
AMOUNT OF LED DETECTION
The ADP1655 is able to detect the amount of LED connected in
series between the LED_OUT pin and the PGND potential. In
I
register. The part uses an 80 mA LED driver current setting to
detect the LED forward voltage (Vf) with a voltage comparator
at the start of a flash, torch, or assist light event. If the detected
forward voltage is higher than 4.3 V (typical), Bit 3 of the fault
information register is read back as high.
INPUT UNDERVOLTAGE
The ADP1655 includes an input undervoltage lockout circuit. If
the battery voltage drops below the 2.4 V (typical) input UVLO
threshold, the ADP1655 shuts down. In this case, information
in all registers is lost, and when power is reapplied, a power-on
reset circuit resets the registers to their default conditions.
2
C mode, the detection is enabled with Bit 3 in the output mode
ADP1655
2
C mode,