EVAL-ADP1653EB
Rev. A | Page 7 of 20
Applying a TxMask voltage reduces the SETF reference current
and therefore reduces the HPLED current. The maximum
TxMask voltage allowed for R4 and R5 is
⎟
⎠
⎞
⎜
⎝
⎛+×= R5
R4
VTxMask 1V2.1
Using a larger TxMask voltage causes a negative reference
current and triggers the overvoltage protection. The interrupt
LED turns on to indicate the fault.
Table 1 shows the maximum HPLED current (code = 31) for
various values of R4, R5, and TxMask voltage. The first entry
(R4 = 99999, R5 = 50 kΩ, and TxMask = Z) simulates the default
internal reference current obtained by tying the SETF pin high.
R4 = 99999 is equivalent to R4 being any numerical value.
Table 1. Maximum HPLED Currents
R4 (kΩ) R5 (kΩ)
TxMask
Voltage (V)
Maximum
HPLED Current (mA)
99999150 Z 500
50 50 1.8 250
332 105 0 313
150 50 3.3 208
1R4 = 99999 is equivalent to R4 being any numerical value.
Slide the HPLED Current scroll bar to the desired setting and
click UPDATE! to change the HPLED settings. Settings 1 to 11
are torch mode, and settings 12 to 31 are flash mode. All the
settings are indicated next to the HPLED Current scroll bar.
When the device is in flash mode, you must click either the
Physical Strobe button on the motherboard or the STROBE!
button in the software to flash the LEDs. Clicking Reset Fault
clears any interrupts by resetting both ILED and HPLED
settings to 0.
SOFTWARE STROBE
Instead of using the Hardware Strobe button on the motherboard,
an I2C software strobe can be used. When the HPLED register is in
the flash setting, click STROBE! to flash the LEDs.
CLOCK AND TIMEOUT DURATION PROGRAMMING
Oscillator Frequency
Because the timeout duration that the software reports is based
on the default 1.2 MHz, if the oscillator frequency is not exactly
1.2 MHz, the timeout duration shown is incorrect. As a result,
you can enter the exact oscillator frequency measured on a scope
and then click UPDATE! to calculate the correct timeout duration.
Timeout Configuration
The user can choose to run the device in the timed or untimed
mode. In timed mode, the LEDs flash for the programmed timeout
duration even if the strobe button is released prior to the end of
the duration. In untimed mode, the LEDs flash for as long as the
hardware strobe button is pressed until the programmed timeout
duration is reached. The part then issues a timeout fault, and the
interrupt LED lights up.
Timeout Value
The Time Out Value drop-down box is used to program the
timeout duration.
FAULT DETECTION STATUS
The Register 3 – Fault Register section is used to read back the
fault detection status from the ADP1653. When a fault occurs,
the interrupt LED on the motherboard lights up. Click READ! to
view information about the fault. Overvoltage fault occurs when
the output voltage is greater than 10.2 V (nominal). Timeout
fault occurs when the user presses the strobe button longer than
the programmed timeout duration in the untimed mode.
Thermal fault occurs when the device junction temperature is
greater than 155°C. Short-circuit fault occurs if the HPLED pin
remains grounded 820 ms after torch is enabled.
REGISTER VALUES
The register values section displays the value in each register in the
hexadecimal format.
AUTO RANGE FINDER
The Auto Range Finder box is used to simulate the function of
a camera’s auto range finder, which is used to torch the LEDs to
focus on the object in a dark room, for example, and then to
flash the LEDs and take a picture. To use this feature, select the
desired setting for both the torch and flash modes (1 to 11 for
torch, 12 to 31 for flash). Then click Torch Then Flash once to
torch the LEDs and once more to initiate a flash.
