S-8365AAABA-M5T1Y2 Datasheet, PDF (21/63 Pages) Seiko Instruments Inc – PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER

STEP-UP, SUPER-SMALL PACKAGE, 1.2 MHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER
Rev.2.1_01
S-8365/8366 Series
2. Diode
Use an externally mounted that meets the following conditions.
• Low forward voltage (Schottky barrier diode or similar type)
• High switching speed
• Reverse withstand voltage of VOUT + spike voltage or more
• Rated current of IPK or more
3. Input capacitor (CIN) and output capacitor (COUT)
To improve efficiency, an input capacitor (CIN) lowers the power supply impedance and averages the input current.
Select CIN according to the impedance of the power supply used. The recommended capacitance is 10 μF for the
S-8365/8366 Series.
An output capacitor (COUT), which is used to smooth the output voltage, requires a capacitance larger than that of
the step-down type because the current is intermittently supplied from the input to the output side in the step-up
type. A 22 μF ceramic capacitor is recommended for the S-8365/8366 Series. However, a higher capacitance is
recommended if the output voltage is high or the load current is large. If the output voltage or load current is low,
about 10 μF can be used without problems.
Select COUT after sufficient evaluation with actual application.
A ceramic capacitor can be used for both the input and output.
4. Capacitor for setting short-circuit protection delay time (CSP) (products with short-circuit
protection)
For the S-8365/8366 Series, the short-circuit protection delay time can be set to any value by using an external
capacitor. Connect the capacitor between the CSP and VSS pins. Select the capacitor value according to the
equation below and Figure 18.
Note, however, that the equation and figure show a theoretical value assuming an ideal capacitor value and typ. IC
conditions. Variations of the capacitor and IC are not considered.
For the IC variations, see the short-circuit protection delay time (tPRO) in “ Electrical Characteristics”.
CSP [μF] ≅
tPRO [ms] × 1.2 × 10^−3
0.6
120
100
80
60
40
20
00
0.05 0.10 0.15 0.20 0.25
CSP [μF]
Figure 18 CSP vs. tPRO
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