9.1.2 Monitoring a Voltage Other than (V+)

Some applications monitor rails other than the one that is powering the comparator. In these applications the

resistor divider used to set the desired threshold is connected to the rail that is being monitored.

Supply

IN

OUT

V+

s5

REF

TLV40x1

Figure 9-2. Monitoring a Voltage Other than the Supply

The TLV40x1Ry can monitor a voltage greater than the maximum (V+) with the use of an external resistor divider

network. Likewise, the TLV40x1 can monitor voltages as low as the internal reference voltage (0.2 V, 0.5 V,

or 1.2 V). The TLV40x1Ry also has the advantage of being able to monitor high impedance sources since the

input bias current of the input (IN) is low. This provides an advantage over voltage supervisors that can only

monitor the voltage rail that is powering them. Supervisors configured in this fashion have limitations in source

impedance and minimum sensing voltage.

For applications where the output of the comparator needs to interface with a reset/enable pin that operates

from a different supply voltage, the open-drain comparators (TLV4021/4031) should be selected. In these usage

cases, the output can be pulled up to any voltage that is lower than 5.5V (independent of (V+)). This technique is

commonly referred to as "level-shifting."

IN

OUT

V+

s5

Supply

(up to 5.5V)

Figure 9-3. Level-Shifting

TLV4021, TLV4031, TLV4041, TLV4051

SNVSB04C – MARCH 2019 – REVISED DECEMBER 2021

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