SM8135A
The mode reset operation when in ×2.0 mode performs boost mode switching between ×2.0 mode and ×1.5
mode. Mode switching directly from ×2.0 mode to ×1.0 mode does not occur.
Mode reset
VOUT mode
1.0sec/cycle
2.0 mode
1.ꢁ mode
2.0 mode
min ꢀ0µs
Mode hold
(L: hold)
max 200µs
ILED detector
ignore
4.9V
VOUT output voltage
ILED detector
Switching from ×2.0 mode to ×1.5 mode due to mode reset signal
(1) Mode switches from ×2.0 to ×1.5 mode on the rising edge of the mode reset signal.
(2) A 200µs (max) mode hold time begins after switching to ×1.5 mode. LED drive current insufficient state is
detected but the mode is not switched during this interval.
(3) LED drive current insufficient signal is ignored during the mode hold time, but normal mode switching
operation resumes when the mode hold time elapses.
The mode reset function periodically tests the boost mode to try to maximize the duration of operation in the
higher efficiency ×1.0 and ×1.5 modes in order to extend battery drive time.
Thermal Shutdown Circuit (Overtemperature Protection Circuit)
The SM8135A features a thermal shutdown circuit that operates whenever the IC temperature exceeds approx-
imately 170°C for whatever reason, stopping the V
ature falls below approximately 150°C.
output. V
output recommences when the IC temper-
OUT
OUT
SEIKO NPC CORPORATION —13
NPC [ NIPPON PRECISION CIRCUITS INC ]
