S-8327 Seiko, S-8327 Datasheet - Page 46

• Manufacturer Part Number: S-8327
• Description: (S-8323 / S-8327) SMALL PACKAGE PWM CONTROL STEP-UP SWITCHING REGULATOR
• Manufacturer: Seiko

Collection of Product FAQs
Author: Tachibana Midori
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Question:
Answer:
B:
Index:
Division name: 01 IC
Category 1:
Category 2:
Cal No.:
What about the soft-start mechanism of the S-8323/24/27/28?
The soft-start function has been added to prevent overshoot of the output voltage when the boosting
operation is initiated, and to suppress the rush current during voltage increases. The following are
among the soft-start methods available:




This IC adopts method
The waveforms observed when the S-8327B30 is soft-started are shown below. As reference voltage
VREF within the measurement circuit is increased slowly from 0 V, output voltage VOUT also slowly
increases. [Vref indicated with dotted lines in the waveform is the value obtained when reference
voltage VREF is converted to an output voltage VOUT level (Vref = VREF x (R1 + R2)
VOUT increases to close to VIN immediately after the power is switched on, as the current is supplied
from VIN to VOUT via L and SD of the measurement circuit.
implemented by an output-power regulation circuit allows an extended soft-start time to be ensured
when a large external Cc is selected.
(Refer to FAQ No. 11S8323007.)
Measurement Circuit: S-8327B30 VIN = 0
Placing a current limit on the switching current
Slowly increasing the reference voltage
Limiting on-duty at the start
For Distri & Rep (Printing N.G.)
B: Technical
11 Power Supply
4. Switching Regulators
S-8323/24/27/28

above.
Date: 98/11/12 (Thursday) 10:17 (Modified:)
1.8 V IOUT = 1 mA
45
Moreover, the soft-start function
R2).]