V

IN

V

REF

V

OUT

V

S

0.1µF

2.2µF

TLV3501

R

V+

f = 10MHz

V

2/3 (V+)

1/3 (V+)

R

1

1kΩ

R

2

5kΩ

R

2

5kΩ

R

2

5kΩ

V

OUT

V

C

V+

t

C

62pF

1.38R

t

TLV3502-Q1

SBOS507 – FEBRUARY 2010

www.ti.com

Input Over-Voltage Protection

Device inputs are protected by ESD diodes that will conduct if the input voltages exceed the power supplies by

more than approximately 300 mV. Momentary voltages greater than 300 mV beyond the power supply can be

tolerated if the input current is limited to 10 mA. This limiting is easily accomplished with a small input resistor in

series with the comparator, as shown in Figure 3.

Figure 3. Input Current Protection for Voltages Exceeding the Supply Voltage

Relaxation Oscillator

The TLV350x can easily be configured as a simple and inexpensive relaxation oscillator. In Figure 4, the R2

network sets the trip threshold at 1/3 and 2/3 of the supply. Since this is a high-speed circuit, the resistor values

are rather low to minimize the effect of parasitic capacitance. The positive input alternates between 1/3 of V+ and

10.9MHz. An implementation of this circuit oscillated at 9.6 MHz. Parasitic capacitance and component

tolerances explain the difference between theory and actual performance.

Figure 4. Relaxation Oscillator

High-Speed Window Comparator

A window comparator circuit is used to determine when a signal is between two voltages. The TLV3502 can

shows a simple means of obtaining an active low output. Note that the reference levels are connected differently

between Figure 5 and Figure 6. The operating voltage range of either circuit is 2.7 V to 5.5 V.

8

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