7

LTC1841/LTC1842/LTC1843

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 0.01

µF 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

0.1

µF capacitor.

Comparator Inputs

The comparators’ input can swing from the negative

without damage and the typical input leakage current is

only

±10pA.

Comparator Outputs

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.

Voltage Reference

The internal bandgap reference has an output voltage of

from – 40

°C to 85°C. It can typically source greater than

1mA and sink up to 10

µA with a 5V supply. The reference

can drive a bypass capacitor of up to 0.01

µF without

oscillation. By inserting a series resistor, capacitance

values up to 100

µF can be used (Figure 1).

Figure 1. Damping the Reference Output

Figure 3 shows the bypassed reference output with a

a 10mV hysteresis voltage band while R1 damps the

reference response. Note that the comparator output

doesn’t trip.

CAPACITOR VALUE (

µF)

0.001

0.1

10

0.01

0.1

10

1

1841/43 F02

1

100

Figure 2. Damping Resistance vs Bypass Capacitor Value

LTC1843

REF

R1

C1

REFERENCE

OUTPUT

1841/43 F01

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-

transients from disturbing the reference output voltage.