TC54VC datasheet(6/16 Pages) MICROCHIP

6 / 16 page

TC54

DS21434H-page 6

4.0

APPLICATIONS INFORMATION

4.1

Modifying the Trip Point, VDET –

Although the TC54 has a pre-programmed VDET –, it is

sometimes necessary to make adjustments during

prototyping. This can be accomplished by connecting

an external resistor divider to a TC54, which has a

VDET – lower than that of VSOURCE (Figure 4-1).

To maintain detector accuracy, the bleeder current

through the divider should be significantly higher than

the 1 µA operating current required by the TC54. A

reasonable value for this bleeder current is 100 µA (100

times the 1 µA required by the TC54). For example, if

VDET – = 2V and the desired trip point is 2.5V, the value

of R1 + R2 is 25 kΩ (2.5V/100 µA). The value of R1 + R2

can be rounded to the nearest standard value and

plugged into the equation of Figure 4-1 to calculate

values for R1 and R2. 1% tolerance resistors are

recommended.

FIGURE 4-1:

Modify Trip-point of the

TC54 using External Resistor Divider.

4.2

Other Applications

Low operating power and small physical size make the

TC54

series

ideal

for

many

voltage

detector

applications, such as those shown in Figures 4-2, 4-3

and 4-4. Figure 4-2 shows a low-voltage gate drive

protection circuit that prevents overheating of the logic-

level MOSFET due to insufficient gate voltage. When

the input signal is below the threshold of the TC54VN,

its output grounds the gate of the MOSFET. Figure 4-3

and Figure 4-4 show the TC54 in conventional voltage

monitoring applications.

FIGURE 4-2:

MOSFET Low Drive

Protection.

FIGURE 4-3:

Battery Voltage Monitor.

FIGURE 4-4:

Power Good Monitor.

Note:

In this example, VSOURCE must be

greater than (VDET –)

SOURCE

--------------------

DET

TC54

VIN

VOUT

VSS

VSOURCE

Where:

VSOURCE

Voltage to be monitored

VDET –

Threshold Voltage setting of

TC54

VIN

VOUT

VSS

TC54VX

270

MTP3055EL

VCC

4.3V

VIN

VOUT

VSS

BATLOW

TC54VX

–

VIN

VOUT

VSS

Power Good

TC54VX

–

Pwr

Sply

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