8

LTC1440/LTC1441/LTC1442

R1

430

Ω

R2

10k

C1

1

µF

5V

TO

8V

OUT

21

7

8

GND

LTC1440

1440/1/2 F03a

HYST

REF

3

4

5

6

R3

2.4M

–

+

Figure 3a. Reference Transient Response Test Circuit

2ms/ DIV

1440/1/2 F03b

8V

5V

OUT

Hysteresis

Hysteresis can be added to the LTC1440 by connecting a

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

The difference between the upper and lower threshold

the voltage difference between the REF and HYST pins.

When more hysteresis is added, the upper threshold

increases the same amount as the low threshold de-

creases. The maximum voltage allowed between REF and

HYST pins is 50mV, producing a maximum hysteresis

voltage band of 100mV. The hysteresis band could vary by

up to 15%. If hysteresis is not wanted, the HYST pin

from 0.1

µA to 5µA. If 2.4M is chosen for R2, then the value

Figure 5. Glitch-Free Level Detector with Hysteresis

R5

430

Ω

5%

R3

15k

1%

C1

1

µF

OUT

21

7

5V

8

GND

LTC1440

1440/1/2 F05

HYST

REF

3

4

5

6

–

+

R2

3.4M

1%

R1

1.18M

1%

R4

2.4M

1%

6

R2

HYST

REF

5

R1

1440/1/2 F04

LTC1440

2

R1 =

R2 =

1.182V –

()

2

Figure 4. Programmable Hysteresis

Level Detector

The LTC1440 is ideal for use as a micropower level

detector as shown in Figure 5. R1 and R2 form a voltage

and R4 set the hysteresis voltage, and R5 and C1 bypass

the reference output. The following design procedure can

be used to select the component values:

Figure 3b. Reference and Comparator Output

Transient Response