CXA2534Q
2. DC-to-DC Converter
a) VCC1 Voltage Setting
The VCC1 voltage can be adjusted by varying the two external resistors, R1 and R2. The formula for
VCC1 Voltage setting is:
R1R3
R2R4
+
R1+R3
R2+R4
VCC1 = 1.23
(V)
R2R4
R2 R4
+
where R1 - External Resistor
R2 - External Resistor
R3 - 35 kΩ
R4 - 21 kΩ
CXA2534Q
VCC1
3
R1
R3
R4
EI
43
R2
1.23V
b) Short Circuit Protection
If the VCC1 falls below the designed voltage for a long time, it will be considered as a short circuit at the
VCC1. In this case, the IC will detect this prolong drop in VCC1 and turn off the IC.
When the VCC1 is below the designed voltage, the error amplifier will output an HIGH at its EO pin (pin
42). The High level at EO pin will cause the SPRT pin’s capacitor (pin 44) to charge up by a constant
current of 10 µA. Once the voltage is above 1.23 V (typical), the IC will turn off. The duration of the
short circuit can be varied by the SPRT pin’s capacitor.
1.23V
t =
× CSPRT
(sec)
10µA
—20—
SONY [ SONY CORPORATION ]
