6

LTC1540

sn1540 1540fas

R1

430Ω

R2

10k

C1

1µF

5V

TO

8V

OUT

21

7

8

GND

LTC1540

1540 • F03a

HYST

REF

3

4

5

6

R3

2.4M

–

+

LTC1540

REF

R1

C1

REFERENCE

OUTPUT

1540 • F01

Figure 1. Damping the Reference Output

Figure 2. Damping Resistance vs Bypass Capacitor Value

Figure 3 shows the bypassed reference output with a

10mV of hysteresis voltage band while R1 damps the

reference response. Note that the comparator output

doesn’t trip.

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

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 below

2V is anticipated. Because of the increase in supply

current, operation below 1.5V is not recommended

(Figure 4).

Figure 4. Supply Current vs Supply Voltage

SUPPLY VOLTAGE (V)

0

3

4

5

2.0

1540 F04

2

1

0

0.5

1.0

1.5

2.5

Figure 3a. Power Supply Transient Test Circuit

CAPACITOR VALUE (µF)

0.001

0.1

10

1000

0.01

0.1

10

1

1540 • F02

1

100

Figure 3b. Power Supply Transient Rejection

2ms/DIV

1540 F03b

8V

5V

OUT