LTC1443IN-PBF 查看數據表（PDF） - Linear Technology

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LTC1443IN-PBF

Ultralow Power Quad Comparators with Reference

Linear Technology 

LTC1443/LTC1444/LTC1445

Applications Information

Level Detector

The LTC1444 is ideal for use as a multisupply micropower

level detector as shown in Figure 5.

R1 and R2 form a voltage divider from V1 to the non-

inverting comparator A input. R6 and R7 are used to

divide down V2, while R8 is the output pull-up resistor

for the comparator outputs. R3 and R4 set the hysteresis

voltage and R5 and C1 bypass the reference output.

5V

V2

R6

1.82M

1%

3

V+

7 IN B+ +

R8

2M

1%

OUT B 1

V1

6 IN B– –

R2

3.40M

1%

R7

1.21M

1%

R1

R3

1.21M 15k, 1%

1%

5 IN A+ +

4 IN A– –

1/2LTC1444

OUT A 2

14 HYST

8 REF

R4

2.4M

1%

R5

430Ω

5%

C1

1.0µF

+– 1.2V

V–

9

144345 F05

Figure 5. Glitch-Free Level Detector with Hysteresis

The following design procedure can be used to select the

component values:

1. Choose the V1 voltage trip level, in this example 4.65V.

2. Calculate the required resistive divider ratio.

Ratio = VREF/ VIN

Ratio = 1.221V/4.65V = 0.263

3. Choose the required hysteresis voltage band at the input,

VHBIN, in this example 60mV. Calculate the hysteresis

voltage band referred to the comparator input VHB.

VHB = (VHBIN)(Ratio)

VHB = (60mV)(0.263)

VHB = 15.78mV

4. Choose the values for R3 and R4 to set the hysteresis.

R4 = 2.4M

R3(kΩ) = VHB = 15k

5. Choose the values for R1 and R2 to set the trip point.

R1 = VREF/IBIAS = 1.221V/1µA ≈ 1.21M





R2

=

(R1)





VIN

VREF +

VHB

2



− 1









R2

=

(1.21M)

 4.65V



1.221V

+

15mV

2

−



1





R2 = 3.40M

Using the same equations, R6 and R7 are 1.82M and

1.21M, respectively, to set the trip level at 3V for V2.

10

144345fe

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