TLV3501

TLV3502

SBOS321D − MARCH 2005 − REVISED JULY 2005

www.ti.com

7

APPLICATIONS INFORMATION

The TLV3501 and TLV3502 both feature high-speed

response and includes 6mV of internal hysteresis for

improved noise immunity with an input common-mode

range that extends 0.2V beyond the power-supply rails.

SHUTDOWN

A shutdown pin allows the device to go into idle when it is

not in use. When the shutdown pin is high, the device

draws about 2

µA and the output goes to high impedance.

When the shutdown pin is low, the TLV3501 is active.

When the TLV3501 shutdown feature is not used, simply

connect the shutdown pin to the most negative supply, as

shown in Figure 1. It takes about 100ns to come out of

shutdown mode. The TLV3502 does not have the

shutdown feature.

V

IN

V

REF

V

OUT

V

S

0.1

µF2.2µF

TLV3501

Figure 1. Basic Connections for the TLV3501

OPERATING VOLTAGE

TLV3501 comparators are specified for use on a single

supply from +2.7V to +5.5V (or a dual supply from

±1.35V

to

±2.75V) over a temperature range of −40°C to +125°C.

The device continues to function below this range, but

performance is not specified.

ADDING EXTERNAL HYSTERESIS

The TLV350x has a robust performance when used with a

good layout. However, comparator inputs have little noise

immunity within the range of specified offset voltage

(

±5mV). For slow moving or noisy input signals, the

comparator output may display multiple switching as input

signals move through the switching threshold. In such

applications, the 6mV of internal hysteresis of the TLV350x

might not be sufficient. In cases where greater noise

immunity is desired, external hysteresis may be added by

connecting a small amount of feedback to the positive

input. Figure 2 shows a typical topology used to introduce

25mV of additional hysteresis, for a total of 31mV

hysteresis when operating from a single 5V supply. Total

hysteresis is approximated by Equation 1:

V

( V

))

R

1

R

1

) R

2

) 6mV

switch the comparator output by enlarging the threshold

region, thereby reducing sensitivity to noise.

V

IN

V

REF

V

OUT

V

0.1

µF2.2µF

TLV3501

R

R

Figure 2. Adding Hysteresis to the TLV350x

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 300mV. Momentary voltages

greater than 300mV beyond the power supply can be

tolerated if the input current is limited to 10mA. This limiting

is easily accomplished with a small input resistor in series

with the comparator, as shown in Figure 3.

V

IN

V

REF

V

OUT

V

S

0.1

µF2.2µF

TLV3501

R

Figure 3. Input Current Protection for Voltages

Exceeding the Supply Voltage

(1)