s-8333aaca-t8t1g Seiko Instruments Inc., s-8333aaca-t8t1g Datasheet - Page 11

• Manufacturer Part Number: s-8333aaca-t8t1g
• Description: Step-up, For Lcd Bias Supply, 1-channel, Pwm Control Switching Regulator Controller
• Manufacturer: Seiko Instruments Inc.

Rev.2.3
STEP-UP, FOR LCD BIAS SUPPLY, 1-CHANNEL, PWM CONTROL SWITCHING REGULATOR CONTROLLER
3. Timer latch short-circuit protection function
4. UVLO function
This IC has a timer latch short-circuit protection circuit that stops the switching operation when the output voltage
drops for a specific time due to output short-circuiting. A capacitor (CSP) that is used to set the delay time of this
short-circuit protection circuit can be connected to the CSP pin.
This IC operates at the maximum duty ratio if the output voltage drops due to output short-circuiting. At the
maximum duty ratio, constant-current charging of CSP starts. If this status lasts for a short-circuit protection
delay time and the CSP pin voltage rises above the reference voltage, the latch mode is set. Note that the latch
mode is different from the shutdown status in that the switching operation is stopped but the internal circuitry
operates normally.
To reset the latch operation to protect the IC from short-circuiting, lower V
The latch mode within the short-circuit protection delay time is reset by decreasing V
Note that the mode is not reset even if the V
This IC includes a UVLO (under-voltage lockout) circuit to prevent the IC from malfunctioning due to a transient
status when power is applied or a momentary drop of the power supply voltage. When UVLO is in the detection
state, switching is stopped and the external FET is held in the off status. Once UVLO enters the detection state,
the soft-start function is reset.
Note that the other internal circuits operate normally and that the status is different from the power-off status.
Input voltage
(V
Output load
CSP pin voltage
(V
Latch mode
_00
IN
CSP
)
)
Reference
UVLO release
UVLO detection
1.0 V
Normal
voltage
status
50 ms (CSP = 0.1 µF)
protection time
Short-circuit
Seiko Instruments Inc.
Short-circuit status
IN
is lowered to the UVLO detection voltage (refer to Figure 9).
Figure 9
period
Latch
Reset period
protection time
IN
Short-circuit
than the UVLO detection voltage.
IN
to 1.0 V (Typ.) or lower.
S-8333 Series
protection time
Reset period
Short-circuit
11