LTC1443CN(RevA) 데이터 시트보기 (PDF) - Linear Technology

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LTC1443CN
(Rev.:RevA)

Ultralow Power Quad Comparators with Reference

Linear Technology 

LTC1443/LTC1444/LTC1445

PI FU CTIO S

OUT D (Pin 15): Comparator D Output. (Open-drain

output for LTC1444). Output can source up to 40mA

(LTC1443, LTC1445) and sink 5mA.

OUT C (Pin 16): Comparator C Output. (Open-drain output

for LTC1444). Output can source up to 40mA (LTC1443,

LTC1445) and sink 5mA.

APPLICATIO S I FOR ATIO

The LTC1443/LTC1444/LTC1445 is a family of quad

micropower comparators with a built-in reference (1.182V

for the LTC1443 and 1.221V for the LTC1444/LTC1445).

Features include programmable hysteresis (LTC1444/

LTC1445), wide supply voltage range (2V to 11V) and the

ability of the reference to drive up to a 0.01µF capacitor

without oscillation. The comparator CMOS outputs

(LTC1443/LTC1445) can source up to 40mA while the

LTC1444 has an open-drain output to V –. The supply

current glitches that normally occur when the comparator

output switches states have been eliminated.

Power Supplies

The comparator family operates from a single 2V to 11V

supply. The LTC1443 includes a separate ground for the

comparator output stage, allowing a split supply ranging

from ±1V to ±5.5V. Connecting V – to GND on the LTC1443

allows single supply operation. If the comparator output

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

impedance is high, V + should be bypassed with a 0.1µF

capacitor.

tions which helps minimize parasitic feedback through the

supply pins.

Voltage Reference

The internal bandgap reference has a voltage of 1.182V for

LTC1443 or 1.221V for LTC1444/LTC1445 referenced to

V –. The reference accuracy is 1.5% from – 40°C to 85°C.

It can source up to 200µA and sink up to 15µA with a 5V

supply. The reference can drive a bypass capacitor of up to

0.01µF without oscillation and by inserting a series resistor,

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

REFERENCE

OUTPUT

R1

REF

LTC144X

C1

V–

LTC1443/44/45 • F01

Figure 1. Damping the Reference Output

Comparator Inputs

The comparator inputs can swing from the negative sup-

ply (V –) to within 1.3V maximum of the positive supply

(V +). The inputs can be forced 300mV below V – or above

V + without damage, and the typical input leakage current

is only ±10pA.

Figure 2 shows the resistor value required for different

capacitor values to achieve critical damping.

1000

100

Comparator Outputs

The LTC1443 comparator output swings between GND

and V + to assure TTL compatibility with a split supply. The

LTC1444 and LTC1445 outputs swing between V – and V +.

The outputs are capable of sourcing up to 40mA (LTC1443/

LTC1445) and sinking up to 5mA while still maintaining

microampere quiescent currents. The output stage does

not generate crowbar switching currents during transi-

10

1

0.1

0.001

0.01

0.1

1

10

CAPACITOR VALUE (µF)

LTC1443/44/45 • F02

Figure 2. Damping Resistance vs Bypass Capacitor Value

7

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