1841 データシートの表示（PDF） - Linear Technology

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1841

Ultralow Power Dual Comparators with Reference

Linear Technology 

LTC1841/LTC1842/LTC1843

APPLICATIONS INFORMATION

The LTC1841/LTC1842/LTC1843 are dual micropower

comparators with a built-in 1.182V reference (LTC1842/

LTC1843). Features include programmable hysteresis,

wide supply voltage range (2V to 11V) and the ability for

the reference to drive up to a 0.01µF capacitor without

oscillation. The comparators’ open-drain outputs can typi-

cally sink greater than 20mA and the supply current

glitches that normally occur when switching logic states

have been eliminated.

Power Supplies

The comparators operate from a single 2V to 11V (2.5V to

11V for LTC1842/LTC1843) or dual ±1V to ±5.5V supply

(±1.25V to ±5.5V for LTC1842/LTC1843). If the reference

output is required to source more than 1mA or the supply

source impedance is high, V + should be bypassed with a

0.1µF capacitor.

REFERENCE

OUTPUT

R1

REF

LTC1843

C1

V–

1841/43 F01

Figure 1. Damping the Reference Output

Figure 2 shows the resistor value required for different

capacitor values to achieve critical damping. Bypassing

the reference can help prevent false tripping of the com-

parators by preventing glitches on V + or reference load

transients from disturbing the reference output voltage.

Comparator Inputs

The comparators’ input can swing from the negative

supply V – to within 1.3V (max) of the positive supply V +.

The input can be forced 300mV below V – or above V +

without damage and the typical input leakage current is

only ±10pA.

Comparator Outputs

Each comparator output is an open-drain pull-down to V–

typically capable of sinking greater than 20mA. The low

output leakage current while in three-state mode allows a

high value pull-up resistor to be used. The open-drain

outputs can be wire OR-ed or used in level shifting

applications.

100

10

1

0.1

0.001

0.01

0.1

1

CAPACITOR VALUE (µF)

10

1841/43 F02

Figure 2. Damping Resistance vs Bypass Capacitor Value

Voltage Reference

The internal bandgap reference has an output voltage of

1.182V referenced to V –. The reference accuracy is 1.5%

from – 40°C to 85°C. It can typically source greater than

1mA and sink up to 10µA with a 5V supply. The reference

can drive a bypass capacitor of up to 0.01µF without

oscillation. By inserting a series resistor, capacitance

values up to 100µF can be used (Figure 1).

Figure 3 shows the bypassed reference output with a

square wave applied to the V + pin. Resistors R2 and R3 set

a 10mV hysteresis voltage band while R1 damps the

reference response. Note that the comparator output

doesn’t trip.

7

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