MAX8211CTY データシートの表示（PDF） - Maxim Integrated
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MAX8211CTY Datasheet PDF : 7 Pages
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Microprocessor Voltage Monitors
with Programmable Voltage Detection
1.250
1.230
1.210
1.190
1.170
V+ = 16.5V
1.150
1.130
V+ = 2V
1.110
1.090
1.070
1.050
-55
-25
25
75
125
TA (°C)
Figure 4. MAX8211/MAX8212 Threshold Trip Voltage vs.
Ambient Temperature
R3
48.7kΩ
1%
R2
2.2MΩ
1%
R1
750kΩ
1%
VIN
V+
HYST MAX8211
OUT
THRESH
GND
VOUT
(LOW FOR
VIN < 4.5V)
Figure 5. MAX8211 Logic-Supply Low-Voltage Detector
Calculate resistor values for Figure 3 as follows:
1) Choose a value for R1. Typical values are in
the 10kΩ to 10MΩ range.
2) Calculate R2 for the desired upper trip point
VU using the formula:
R2 = R1 × (VU − VTH) = R1 × (VU − 1.15V)
VTH
1.15V
3) Calculate R3 for the desired amount of
hysteresis, where VL is the lower trip point:
R3 = R2 × (V + − VTH) = R2 × (V + − 1.15V)
(VU − VL)
(VU − VL)
or, if V+ = VIN:
R3 = R2 × (VL − VTH) = R2 × (VL − 1.15V)
(VU − VL)
(VU − VL)
Figure 5 shows an alternate circuit, suitable only when the
voltage being detected is also the power-supply voltage
for the MAX8211 or MAX8212.
Calculate resistor values for Figure 5 as follows:
1) Choose a value for R1. Typical values are in
the 10kΩ to 10MΩ range.
2) Calculate R2:
R2 = R1 × (VL − VTH) = R1 × (VL − 1.15V)
VTH
1.15V
3) Calculate R3:
R3 = R1 × (VU − VL)
1.15V
Low-Voltage Detector for Logic Supply
The circuit of Figure 5 will detect when a 5.0V (nominal)
supply goes below 4.5V, which is the VMIN normally
specified in logic systems. The selected resistor values
ensure that false undervoltage alarms will not be gener-
ated, even with worst-case threshold trip values and
resistor tolerances. R3 provides approximately 75mV of
hysteresis.
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