SM8135A
A mode hold signal of 200µs (max) duration is output immediately after switching to ×1.0 mode. The V
OUT
output is held in ×1.0 mode and any LED drive current insufficient detection signal is ignored during the mode
hold signal output. For example, if the V voltage drops and the V
output voltage in ×1.0 mode cannot
IN
OUT
provide sufficient current to drive the LEDs, a LED drive current insufficient condition occurs momentarily due
to the mode reset. The LED low-current detector circuit outputs a LED drive current insufficient signal imme-
diately after switching modes, but during the mode hold time the device stays in ×1.0 mode and does not
switch to ×1.5 mode. Consequently, the V
voltage drops and the LED brightness decreases during the 85µs
OUT
(min) to 200µs (max) mode hold time. However, a 200µs decrease in the brightness is not a problem as it is not
perceptible to the human eye.
1.0
1.ꢁ threshold
VIN input voltage
1.0sec
Mode reset
VOUT mode
max
200µS
Mode hold
(L: hold)
4.9V
VOUT output voltage
ILED detector
(H: lack)
V
drop due to mode reset signal (between ×1.5 and ×1.0 mode)
OUT
SEIKO NPC CORPORATION —12
NPC [ NIPPON PRECISION CIRCUITS INC ]
