S1701 Datasheet, PDF (38/71 Pages) Seiko Instruments Inc – HIGH RIPPLE-REJECTION LOW DROPOUT

HIGH RIPPLE-REJECTION LOW DROPOUT CMOS VOLTAGE REGULATOR WITH RESET FUNCTION
S-1701 Series
Rev.3.1_00
5. Oscillation
In applications where a resistor is connected to the input side (Figure 32), the through-type current which is generated
when the output goes from low to high (release) causes a voltage drop equal to [through-type current] × [input
resistance] across the resistor. When the input voltage drops below the detection voltage as a result, the output
voltage goes from high to low. In this state, the through-type current stops, its resultant voltage drop disappears, and
the output goes from low to high. The through-type current is then generated again, a voltage drop appears, and
repeating the process finally induces oscillation.
VIN
Ra
V_IN
R_b
S-1701
detector
block
VDOUT
VSS
Figure 32 Example of Bad Implementation of Detection Voltage Changer
6. Other characteristics
6. 1 Detection voltage temperature characteristics
The shaded area in Figure 33 is the range where −V_DET varies within the operation temperature range when the
output voltage temperature coefficient is ±140 ppm/°C.
−V_DET
[V]
Example of −V_DET = 3.0 V product
+0.42 mV/°C
3.000
−0.42 mV/°C
−40
+25
+85
Ta [°C]
Figure 33
38
Seiko Instruments Inc.