Datasheet

LTC15 4 0
7
1540fb
For more information www.linear.com/LTC1540
APPLICATIONS INFORMATION
Figure 1. Damping the Reference Output
Figure 2. Damping Resistance vs Bypass Capacitor Value
Figure 3 shows the bypassed reference output with a square
wave applied to the V
+
pin. Resistors R2 and R3 set 10mV
of hysteresis voltage band while R1 damps the reference
response. Note that the comparator output doesn’t trip.
Low Voltage Operation: V
+
= 1.6V
The guaranteed minimum operating voltage is 2V (or
±1V). As the total supply voltage is reduced below 2V,
the performance degrades and the supply current falls.
At low supply voltages, the comparator’s output drive is
reduced and the propagation delay increases. The V
REF
and V
OS
are also slightly worse. The useful input voltage
range extends from the negative supply to 0.9V below
the positive supply. Test your prototype over the full
temperature and supply voltage range if operation be-
low 2V is anticipated. Because of the increase in sup-
ply current, operation below 1.5V is not recommended
(Figure 4).
Figure 4. Supply Current vs Supply Voltage
Figure 3a. Power Supply Transient Test Circuit
Figure 3b. Power Supply Transient Rejection
LTC1540
V
–
REF
R1
C1
REFERENCE
OUTPUT
1540 • F01
CAPACITOR VALUE (µF)
0.001
0.1
RESISTOR VALUE (kΩ)
10
1000
0.01 0.1 101
1540 • F02
1
100
V
+
R1
430Ω
R2
10k
C1
1µF
5V
TO
8V
OUT
V
–
2 1
7
8
GND
LTC1540
1540 • F03a
IN
+
IN
–
HYST
REF
3
4
5
6
R3
2.4M
–
+
SUPPLY VOLTAGE (V)
0
SUPPLY CURRENT (µA)
3
4
5
2.0
1540 F04
2
1
0
0.5
1.0
1.5
2.5
V
–
= GND = 0V
IN
+
= 0V
IN
–
= REF = HYST
T
A
= 25°C
2mV/DIV
8V
V
+
1540 F03b
5V
V
REF
OUT
2ms/DIV
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