LTC1443 View Datasheet(PDF) - Linear Technology

Part Name

Description

Manufacturer

LTC1443

Ultralow Power Quad Comparators with Reference

Linear Technology 

LTC1443/LTC1444/LTC1445

Applications Information

Bypassing the reference can help prevent false tripping of

the comparators by preventing glitches on the V+ or the

reference output voltage. Figure 3 shows the bypassed

reference output with a square wave applied to the V+ pin.

Resistors R1 and R2 set 10mV of hysteresis, while R3

damps the reference response. Note that the comparator

output doesn’t trip.

5V

TO 8V

R1

10k

R2

2.4M

3

V+

5 IN A+ +

4 IN A– –

2 OUT

14 HYST

8 REF

LTC1445

R3

430Ω

C1

1.0µF

+– 1.2V

V–

9

144345 F03a

Figure 3a. V + Glitching Test Circuit

Hysteresis

Hysteresis can be added to the LTC1444/LTC1445 by con-

necting a resistor (R1) between the REF and HYST pins,

and a second resistor (R2) from HYST to V – (Figure 4).

The difference between the upper and lower threshold volt-

ages or hysteresis voltage band (VHB) is equal to twice the

voltage difference between the REF and HYST pins. When

more hysteresis is added, the upper threshold increases

the same amount as the lower threshold decreases. The

maximum voltage allowed between REF and HYST is

50mV, producing a maximum hysteresis voltage band of

100mV. If hysteresis is not wanted, the HYST pin should

be shorted to REF. Acceptable values for IREF range from

0.1µA to 5µA. If 2.4M is chosen for R2, then R1(kΩ) =

VHB (mV).

IREF

R1

R2

8

REF

LTC1445

14 HYST

9 144345 F04

R1 = VHB

(2)(IREF)

( ) R2 =

1.221V

–

VHB

2

IREF

Figure 4. Programmable Hysteresis

8V

V+

5V

VREF

OUT

2ms/DIV

144345 F03b

Figure 3b. V + Glitching Response

144345fe

9

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