HIGH WITHSTAND-VOLTAGE VOLTAGE REGULATOR WITH RESET FUNCTION
S-87x Series
Rev.8.0_00
Seiko Instruments Inc.
38
2. Load transient response characteristics due to load current fluctuation
An overshoot and an undershoot are caused in the output voltage if the load current is changed from
50 μA to 40 mA while the input voltage is kept constant. Figure 31 shows the output voltage fluctuation
due to a change in the load current. The measuring circuit is shown in Figure 32 for reference. The
latter half of this section describes ringing waveform and parameter dependency.
Overshoot
Load current
Output Voltage deviation
Undershoot
40 mA
50
A
Figure 31 Output voltage fluctuation due to a change in the load current
VSS
VOUT
VIN
Oscilloscope
10:1 probe
R
0
R
1
Power
supply
S-87x
Series
C
L
−
10 μF
−
*1. R
1
=
A 50
]V[V
OUT
μ
[Ω]
*2. R
0
=
mA 40
]V[V
OUT
[Ω]
*3. AL electrolytic capacitor
Figure 32 Measuring circuit
Table 22 Parameter dependency due to load current fluctuation
Series Parameter Conditions
Method to decrease
overshoot
Method to decrease
undershoot
Load current (I
OUT
) 10 to 60 mA, C
L
=10 μF Decrease Decrease
S-8750xxx,
S-8730xxx
Load capacitance (C
L
) 1 to 47 μF, I
OUT
=40 mA Increase Increase
Power supply voltage (V
IN
) (V
OUT
+1) to 24 V Increase Increase
Temperature (Ta)
−40 °C to +85 °C Low temperature Low temperature