Datasheet

"#$%&'
"#$%&(
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 2µA 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
µ
F2.2
µ
F
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
HYST
+
(
V)
)
R
1
R
1
) R
2
) 6mV
V
HYST
sets the value of the transition voltage required to
switch the comparator output by enlarging the threshold
region, thereby reducing sensitivity to noise.
V
IN
V
REF
V
OUT
V
S
=5V
0.1
µ
F2.2
µ
F
TLV3501
R
1
=51
Ω
R
2
=10k
Ω
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
µ
F2.2
µ
F
TLV3501
R
Figure 3. Input Current Protection for Voltages
Exceeding the Supply Voltage
(1)