S-8550AA-M5T1X Datasheet, PDF (14/31 Pages) Seiko Instruments Inc – RECTIFICATION, PWM CONTROL SWITCHING REGULATORS

STEP-DOWN, BUILT-IN FET, SYNCHRONOUS RECTIFICATION, PWM CONTROL SWITCHING REGULATORS
S-8550 Series
Rev.5.0_01
 Standard Circuits
1. SOT-23-5
FB
VIN CIN
4.7 μF
VIN
Error amplifier
Current limit
circuit
IC internal
power supply
−
+
Reference
voltage
+
PWM control
−
circuit
PWM comparator
Triangular wave
generation
circuit
ON/OFF
circuit
UVLO circuit
*1
CONT
3.3 μH
L
*1
CFB
68 pF
1.0 μF
ON/OFF
VSS
VOUT
RFB1
36 kΩ
RFB2
18 kΩ
COUT
10 μF
*1. Parasitic diode
2. SNT-8A
FB
VIN CIN
4.7 μF
Ground point
Figure 13
VIN
Error amplifier
Current limit
circuit
IC internal
power supply
−
+
Reference
voltage
+
PWM control
−
circuit
PWM comparator
Triangular wave
generation
circuit
ON/OFF
circuit
UVLO circuit
*1
CONT
3.3 μH
L
*1
CFB
68 pF
1.0 μF
ON/OFF
VSS
PVSS
VOUT
RFB1
36 kΩ
RFB2
18 kΩ
COUT
10 μF
Ground point
*1. Parasitic diode
Figure 14
Caution The above connection diagram and constant will not guarantee successful operation. Perform thorough
evaluation using an actual application to set the constants.
14