adm12914-2arqz-rl7 Analog Devices, Inc., adm12914-2arqz-rl7 Datasheet - Page 9

• Manufacturer Part Number: adm12914-2arqz-rl7
• Description: ?0.8% Accurate Quad Uv/ov Positive/negative Voltage Supervisor
• Manufacturer: Analog Devices, Inc.

Preliminary Technical Data
THEORY OF OPERATION
VOLTAGE SUPERVISION
The ADM12914 supervises up to four voltage rails for under-
voltage overvoltage conditions. Two pins, VHx and VLx, are
assigned to monitor each rail, one for overvoltage detection and
the other for undervoltage detection. Each pin is connected to
the input of an internal voltage comparator, and its voltage level
is internally compared with a 0.5 V voltage reference with a very
high accuracy of ±0.8%. The device is specified over the extended
operating temperature range from −40°C to +125°C.
The output of each of the internal undervoltage comparators is
tied to a common UV output pin. Likewise, the outputs of the
internal overvoltage comparators are tied to a common OV
output pin.
Table 5. Polarity Configuration
SEL Pin
Connected to V
Left Unconnected
Connected to GND
PSU
5V
3.3V
2.5V
1.8V
CC
Figure 16. Typical Applications Diagram
VH1
VL1
VH2
VL2
VH3
VL3
VH4
VL4
REF
Polarity
Positive
Positive
Negative
ADM12914
GND
V
CC
LATCH/DIS
TIMER
UV Condition
VH3 < 0.5 V
VH3 < 0.5 V
VL3 > 0.5 V
SEL
OV
UV
Input 3
SYSTEM
Rev. PrA | Page 9 of 16
OV Condition
VL3 > 0.5 V
VL3 > 0.5 V
VH3 < 0.5 V
POLARITY CONFIGURATION
The ADM12914 is capable of monitoring supply voltages of
both positive and negative polarities. The SEL pin is a tristate
pin that determines the polarity of Input 3 and Input 4. As summa­
rized in Table 5, the SEL pin is connected to either GND or V
or is not connected.
When an input is configured to monitor a positive voltage, using
the triple resistor scheme that is shown in Figure 17, VHx is
connected to the high-side tap of the resistor divider and VLx
is connected to the low-side tap of the resistor divider.
Conversely, when an input is configured to monitor a negative
voltage, UVx and OVx are swapped internally. The negative
voltage for monitoring is then connected as shown in Figure 18.
VHx remains connected to the high-side tap and VLx remains
connected to the low-side tap. Within this configuration, an
undervoltage condition occurs when the monitored voltage is less
negative than the programmed threshold, and an overvoltage
condition occurs when the monitored voltage is more negative
than the programmed threshold.
Polarity
Positive
Negative
Negative
UV Condition
VH4 < 0.5 V
VL4 > 0.5 V
VL4 > 0.5 V
Input 4
OV Condition
VL4 > 0.5 V
VH4 < 0.5 V
VH4 < 0.5 V
ADM12914
CC
,