Analog Devices ADP5520, Manual

Page: 7 / 24

EVAL-ADP5520
Rev. 0 | Page 7 of 24
5. To turn off and fade out the backlight, clear Bit 6 in
Register 0x00 and program this setting by clicking the
Program 0x00 button.
The backlight begins to turn off and fade out to zero
current.
The fade timers can be used with the off and dim timers for
fade transitions among on to dim, dim to on, and dim to off.
You can try different fade laws and fade-in/fade-out times to
decide which ones you want.
BACKLIGHT ZONE ADJUSTMENT (MANUAL)
First press the reset button (S17) on the evaluation board to put
the device in a known state; then do the following on the
BackLight Config tab:
1. In the Daylight Max Current drop-down box, select a
daylight zone backlight maximum current setting (for
example, 30 mA); then program this setting by clicking the
Program 0x05 button.
2. In the
Office Max Current
drop-down box, select an office
zone backlight maximum current setting (for example,
10 mA); then program this setting by clicking the
Program
0x07 button.
3. In the Dark Max Current drop-down box, select a dark
zone backlight maximum current setting (for example,
3 mA); then program this setting by clicking the
Program
0x09 button.
4. Set Bit 6 and Bit 7 in Register 0x00 high and then program
these settings by clicking the
Program 0x00 button.
The backlight begins to turn on in the daylight operating
zone and is driven by the current chosen in Step 1.
5. In the Backlight Level Control drop-down box, select the
office operating zone; then program this setting by clicking
the
Program 0x02 button.
The backlight changes to the office operating zone and is
driven by the current chosen in Step 2.
6. In the Backlight Level Control drop-down box, select the
dark operating zone; then program this setting by clicking
the
Program 0x02 button.
The backlight changes to the dark operating zone and is
driven by the current chosen in Step 3.
You can also enable the fade timers for smooth transition
between operating zones.
BACKLIGHT ZONE ADJUSTMENT (AUTOMATIC VIA
AMBIENT LIGHT SENSING)
The ADP5520 contains an ambient light sensor that measures
the output current of an external photosensor. The ADP5520
can switch between backlight operating zones based on ambient
light conditions. You can set threshold points for switching
among the operating zones.
To control automatic backlight adjustment based on ambient
light conditions, first press the reset button (S17) on the evalu-
ation board to put the device in a known state; then do the
following on the
BackLight Config tab:
1. In the Daylight Max Current drop-down box, select a
daylight zone backlight maximum current setting (for
example, 30 mA); then program this setting by clicking the
Program 0x05
button.
2. In the Office Max Current drop-down box, select an office
zone backlight maximum current setting (for example,
10 mA); then program this setting by clicking the
Program
0x07 button.
3. In the
Dark Max Current
drop-down box, select a dark
zone backlight maximum current setting (for example,
3 mA); then program this setting by clicking the
Program
0x09 button.
4. In the L2 (Office) Comparator Trip Point drop-down
box, select a threshold for switching between daylight and
office operation (for example, 32 μA
1
); then program this
setting by clicking the Program 0x0D button.
5. In the L2 (Office) Comparator Hysteresis drop-down
box, select a hysteresis level for switching between daylight
and office operation (for example, 4 μA); then program
this setting by clicking the
Program 0x0E button.
6. In the L3 (Dark) Comparator Trip Point drop-down box,
select a threshold for switching between office and dark
operation (for example, 15 μA
1
); then program this setting
by clicking the
Program 0x0F
button.
7. In the L3 (Dark) Comparator Hysteresis drop-down box,
select a hysteresis level for switching between daylight and
office operation (for example, 4 μA); then program this
setting by clicking the
Program 0x10 button.
8. Set Bit 0 and Bit 1 in Register 0x0C high and then program
these settings by clicking the
Program 0x0C button.
9. Set Bit 3 in Register 0x02 high; then program this setting
by clicking the
Program 0x02 button.