S1702 Datasheet, PDF (20/45 Pages) Seiko Instruments Inc – SUPER-LOW CURRENT CONSUMPTION 150 mA VOLTAGE REGULATOR WITH

SUPER-LOW CURRENT CONSUMPTION 150 mA VOLTAGE REGULATOR WITH BUILT-IN HIGH-ACCURACY VOLTAGE DETECTOR AND RESET INPUT FUNCTION
S-1702 Series
Rev.2.1_00
2. 6 Oscillation
In applications where a resistor is connected to the input side (Figure 22), the through-type current which is
generated when the detector output voltage (V_DOUT) 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 detector output voltage (V_DOUT) goes from high to low. In this state, the through-type
current stops, its resultant voltage drop disappears, and the detector output voltage (V_DOUT) 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-1702
VD
block
VDOUT
VSS
Figure 22 Example of Bad Implementation of Detection Voltage Changer
2. 7 Temperature characteristics of detection voltage
The shaded area in Figure 23 is the range where −V_DET varies within the operating temperature range when the
temperature coefficient of the detection voltage is ±100 ppm/°C. (Refer to *7 of Table 7 for how to calculate the
temperature change [mV/°C] of the detection voltage.)
−V_DET [V]
+0.30 mV/°C
3.000
−0.30 mV/°C
−40
25
85 Ta [°C]
Figure 23 Example of Detection Voltage Temperature Characteristics (When −V_DET = 3.0 V Typ.)
2. 8 Temperature characteristics of release voltage
Δ + VDET
The temperature change
of the release voltage is calculated by the temperature change
ΔTa
of the detection voltage as follows:
Δ + VDET ₌ +VDET _× Δ − VDET
ΔTa
− VDET ΔTa
Δ − VDET
ΔTa
The temperature changes of the release voltage and the detection voltage consequently have the same sign.
2. 9 Temperature characteristics of hysteresis voltage
The temperature change of the hysteresis voltage is expressed as ^{Δ + VDET} _− ^{Δ − VDET}
ΔTa
ΔTa
Δ + V DET _− Δ − V DET ₌ V HYS _× Δ − V DET
Δ Ta
Δ Ta
− V DET
Δ Ta
and is calculated as follows:
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Seiko Instruments Inc.