TC54 datasheet(6/20 Pages) MICROCHIP

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TC54

DS21434J-page 6

 2001-2011 Microchip Technology Inc.

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 pro-

totyping. 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 rea-

sonable 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 k (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 applica-

tions, 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 the 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. Figures 4-3

and 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

VIN

VOUT

VSS

VSOURCE

Where:

VSOURCE = Voltage to be monitored

VDET – = Threshold Voltage setting of TC54

TC54

VIN

VOUT

VSS

270



MTP3055EL

VCC

4.3V

TC54VX

VIN

VOUT

VSS

BATLOW

–

TC54VX

VIN

VOUT

VSS

Power Good

–

Pwr

Sply

TC54VX

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