S-812C36AY-X Просмотр технического описания (PDF) - Seiko Instruments Inc
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S-812C36AY-X Datasheet PDF : 26 Pages
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Rev.1.0
HIGH OPERATING VOLTAGE CMOS VOLTAGE REGULATOR
S-812C Series
5. Dropout voltage (Vdrop)
This parameter indicates the difference between the input voltage (VIN1) and the output voltage when output
voltage falls to 98 % of VOUT (E) by gradually decreasing the input voltage (VIN).
Vdrop = VIN1-[VOUT(E) × 0.98]
6. Temperature coefficient of output voltage [∆VOUT/(∆Ta • VOUT)]
The output voltage lies in the shaded area in the whole operating temperature shown in figure 8 when the
temperature coefficient of the output voltage is ±100 ppm/°C.
VOUT
[V]
+0.30mV/°C
VOUT(E)
VOUT (E) is a measured value of
output voltage at 25°C.
-0.30mV/°C
-40
25
85
Ta [°C]
Figure 8 Example for the S-812C30A
Temperature change ratio for output voltage [mV/°C] is calculated by using the following equation.
∆VOUT
∆Ta
[mV/° C]
=
VOUT(S)[V]
×
∆VOUT
∆Ta • VOUT
[ppm/° C]
÷ 1000
Specified output voltage
Temperatures change ratio for output voltage Output voltage temperature coefficient
Description of Operation
VIN
1. Basic operation
Current
Figure 9 shows the block diagram of the S-812C source
series.
Error amplifier
The error amplifier compares a reference voltage
Vref
Vref with a part of the output voltage divided by the
feedback resistors Rs and Rf, and supplies the gate
voltage to the output transistor, necessary to ensure
certain output voltage independent from change of
input voltage and temperature.
Reference
voltage
*
VOUT
Rf
Rs
VSS
* : Parasitic diode
Figure 9 Block Diagram
2. Output transistor
The S-812C Series uses a Pch MOS transistor as the output transistor.
The voltage at VOUT must not exceed VIN+0.3V. When the VOUT voltage becomes higher than that of VIN,
reverse current flows and may break the regulator since a parasitic diode between VOUT and VIN exists
inevitably.
Seiko Instruments Inc.
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