S-1701 Datasheet, PDF (38/70 Pages) Seiko Instruments Inc – HIGH RIPPLE-REJECTION LOW DROPOUT CMOS VOLTAGE REGULATOR WITH RESET FUNCTION

HIGH RIPPLE-REJECTION LOW DROPOUT CMOS VOLTAGE REGULATOR WITH RESET FUNCTION
S-1701 Series
Rev.2.4_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
R_a
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 Temperature characteristics of detection voltage
The shaded area in Figure 33 is the range where V_OUT varies within the operating temperature range
when the temperature coefficient of the output voltage is ±140 ppm/°C.
−V_DET
[V]
Example of products with −V_DET = 3.0 V
+0.42 mV/°C
3.000
−0.42 mV/°C
−40
25
85
Ta [°C]
Figure 33 Detection Voltage Temperature Characteristics
38
Seiko Instruments Inc.