LTC1540I View Datasheet(PDF) - Linear Technology

Part Name

Description

Manufacturer

LTC1540I

Nanopower Comparator with Reference

Linear Technology 

LTC1540

APPLICATIONS INFORMATION

REFERENCE

OUTPUT

R1

REF

LTC1540

C1

V–

1540 • F01

Figure 1. Damping the Reference Output

1000

100

10

1

0.1

0.001

0.01

0.1

1

CAPACITOR VALUE (µF)

10

1540 • F02

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 VREF and VOS 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 below

2V is anticipated. Because of the increase in supply

current, operation below 1.5V is not recommended

(Figure 4).

6

3 IN+

4 IN–

7

V + LTC1540

+

8 OUT

–

5V

5 HYST

TO

8V

R2

10k

6 REF

R3

2.4M

R1

430Ω

C1

1µF

V–

GND

2

1

1540 • F03a

Figure 3a. Power Supply Transient Test Circuit

8V

V+

5V

VREF

OUT

2ms/ DIV

1540 F03b

Figure 3b. Power Supply Transient Rejection

5 V – = GND = 0V

IN+ = 0V

4

IN– = REF = HYST

TA = 25°C

3

2

1

0

0

0.5 1.0 1.5 2.0 2.5

SUPPLY VOLTAGE (V)

1540 F04

Figure 4. Supply Current vs Supply Voltage

sn1540 1540fas

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