S1220PBID Datasheet, PDF (14/18 Pages) ON Semiconductor – Universal Voltage Monitors

MC34161, MC33161, NCV33161
V_in
12V
+
330
8
2.54V
1
Reference
-
0.01
4.7k ⁷
++
+
2.8V
1.6k ^{2 + -}
1.27V
-
++
+
0.6V
3+ _-
1.27V
4
470mH
MPS750
V_O
470
1N5819 ⁺ 1000 ^5.0V/250mA
0.01
1.8k
6
5
47k
0.005
Figure 27. Step−Down Converter
Test
Line Regulation
Load Regulation
Output Ripple
Efficiency
Conditions
V_in = 9.5 V to 24 V, I_O = 250 mA
V_in = 12 V, I_O = 0.25 mA to 250 mA
V_in = 12 V, I_O = 250 mA
V_in = 12 V, I_O = 250 mA
Results
40 mV = ±0.1%
2.0 mV = ±0.2%
50 mVpp
87.8%
The above figure shows the MC34161 configured as a step−down converter. Channel 1 monitors the output voltage while Channel
2 performs the oscillator function. Upon initial powerup, the converters output voltage will be below nominal, and the output of Channel
1 will allow the oscillator to run. The external switch transistor will eventually pump−up the output capacitor until its voltage exceeds
the input threshold of Channel 1. The output of Channel 1 will then switch low and disable the oscillator. The oscillator will commence
operation when the output voltage falls below the lower threshold of Channel 1.
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