Datasheet

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LT1011/LT1011A

Voltage Comparator

The LT

1011 is a general purpose comparator with sig-

nificantly better input characteristics than the LM111.

Although pin compatible with the LM111, it offers four

times lower bias current, six times lower offset voltage and

five times higher voltage gain. Offset voltage drift, a

previously unspecified parameter, is guaranteed at

15µV/°C. Additionally, the supply current is lower by a

factor of two with no loss in speed. The LT1011 is several

times faster than the LM111 when subjected to large

overdrive conditions. It is also fully specified for DC

parameters and response time when operating on a single

5V supply. These parametric improvements allow the

LT1011 to be used in high accuracy (≥12-bit) systems

without trimming. In a 12-bit A/D application, for instance,

using a 2mA DAC, the offset error introduced by the

LT1011 is less than 0.5LSB. The LT1011 retains all the

versatile features of the LM111, including single 3V to

±18V supply operation, and a floating transistor output

with 50mA source/sink capability. It can drive loads refer-

enced to ground, negative supply or positive supply, and

is specified up to 50V between V

–

and the collector output.

A differential input voltage up to the full supply voltage is

allowed, even with ±18V supplies, enabling the inputs to

be clamped to the supplies with simple diode clamps.

, LTC and LT are registered trademarks of Linear Technology Corporation.

■

Pin Compatible with LM111 Series Devices

■

Guaranteed

Max 0.5mV Input Offset Voltage

■

Guaranteed

Max 25nA Input Bias Current

■

Guaranteed

Max 3nA Input Offset Current

■

Guaranteed

Max 250ns Response Time

■

Guaranteed

Min 200,000 Voltage Gain

■

50mA Output Current Source or Sink

■

±30V Differential Input Voltage

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Fully Specified for Single 5V Operation

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SAR A/D Converters

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Voltage-to-Frequency Converters

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Precision RC Oscillator

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Peak Detector

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Motor Speed Control

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Pulse Generator

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Relay/Lamp Driver

10µs 12-Bit A/D Converter

FEATURES

APPLICATIO S

TYPICAL APPLICATIO

DESCRIPTIO

6012

12-BIT

D/A CONVERTER

PARALLEL

OUTPUTS

PARALLEL

OUTPUTS

*R2 AND R4

SHOULD TC TRACK

820Ω

6.98k

R2*

6.49k

FULL-SCALE

TRIM

LM329

R4*

2.49k

10 9 8 7 6 5 4 32

0.001µF

20 14 15 16 17

–15V

3.9k

15V

456789161718192021

SERIAL OUTPUT

INPUT

0V TO 10V 5V

7475

LATCH

AM2504

SAR REGISTER

START CLOCK f = 1.4MHz

1011 TA01

SCP

–

LT1011A

OVERDRIVE (mV)

0.1

200

RESPONSE TIME (ns)

250

300

350

400

1 10 100

1011 TA02

150

100

450

500

FALLING

OUTPUT

RISING

OUTPUT

Response Time vs Overdrive

Summary of content (16 pages)

PAGE 1
LT1011/LT1011A Voltage Comparator U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO The LT ®1011 is a general purpose comparator with significantly better input characteristics than the LM111. Although pin compatible with the LM111, it offers four times lower bias current, six times lower offset voltage and five times higher voltage gain. Offset voltage drift, a previously unspecified parameter, is guaranteed at 15µV/°C. Additionally, the supply current is lower by a factor of two with no loss in speed.
PAGE 2
LT1011/LT1011A W W U W ABSOLUTE MAXIMUM RATINGS (Note 1) Supply Voltage (Pin 8 to Pin 4) .............................. 36V Output to Negative Supply (Pin 7 to Pin 4) LT1011AC, LT1011C .......................................... 40V LT1011AI, LT1011I ............................................ 40V LT1011AM, LT1011M (OBSOLETE) .............. 50V Ground to Negative Supply (Pin 1 to Pin 4) ............ 30V Differential Input Voltage ......................................
PAGE 3
LT1011/LT1011A ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwide specifications are at TA = 25°C. VS = ±15V, VCM = 0V, RS = 0Ω, V1 = –15V, output at pin 7 unless otherwise noted. LT1011AC/AI/AM MIN TYP MAX LT1011C/I/M MIN TYP MAX UNITS 4 4 µV/°C SYMBOL PARAMETER CONDITIONS ∆VOS ∆T Input Offset Voltage Drift (Note 6) TMIN ≤ T ≤ TMAX AVOL *Large-Signal Voltage Gain RL = 1k to 15V, –10V ≤ VOUT ≤ 14.
PAGE 4
LT1011/LT1011A U W TYPICAL PERFOR A CE CHARACTERISTICS Input Bias Current Input Offset Current 45 IB FLOWS OUT OF INPUTS 35 0.7 30 0.6 25 20 15 0.5 0.4 0.3 10 0.2 5 0.1 0 – 50 – 25 0 EQUIVALENT OFFSET VOLTAGE (mV) 0.8 CURRENT (nA) 0 – 50 – 25 25 50 75 100 125 150 TEMPERATURE (°C) Input Characteristics* TA = 25°C – 25 – 30 –1.5 – 2.0 REFERRED TO SUPPLIES 0.4 0.3 NEGATIVE LIMIT 0.
PAGE 5
LT1011/LT1011A U W TYPICAL PERFOR A CE CHARACTERISTICS Response Time Using GND Pin as Output V+ 20mV 10 5mV 2mV V+ 5 VIN 0 –5 VOUT –10 2k –15 V 0 – – 50 VS = ±15V TA = 25°C –100 0 1 4 3 2 TIME (µs) INPUT VOLTAGE (mV) OUTPUT VOLTAGE (V) 15 VIN 10 5 VOUT 0 2k –5 V– –10 5mV 20mV –15 2mV 0 VS = ±15V TA = 25°C – 50 –100 0 1 2 TIME (µs) 1011 G10 Supply Current vs Supply Voltage 0.4 60 0.3 SHORT-CIRCUIT CURRENT 0.2 40 20 0.
PAGE 6
LT1011/LT1011A U W TYPICAL PERFOR A CE CHARACTERISTICS Input Offset Voltage vs Common Mode Voltage INPUT OFFSET VOLTAGE (mV) 2.0 Offset Pin Characteristics CHANGE IN VOS (mV/µA) 2.5 TJ = 25°C 1.5 UPPER COMMON MODE + LIMIT = V – (1.5V) 1.0 0.5 0 0.8 0.6 0.4 0.2 0 – 0.5 –150mV –1.0 – 2.0 – 2.5 VOLTAGE ON PINS 5 AND 6 WITH RESPECT TO V + –100mV V – (OR GND WITH SINGLE SUPPLY) –1.5 CHANGE IN VOS FOR CURRENT INTO PINS 5 OR 6 – 50mV V – 0.1 0.2 0.3 0.4 0.5 0.6 0.
PAGE 7
LT1011/LT1011A U U W U APPLICATIONS INFORMATION 15V 2µF TANT + 8 C8 TO C6 = 0.003µF 7 INPUT OFFSET VOLTAGE (mV) of the comparator, but require a minimum input signal slew rate to be effective. DC hysteresis works for all input slew rates, but creates a shift in offset voltage dependent on the previous condition of the input signal. The circuit shown in Figure 1 is an excellent compromise between AC and DC hysteresis.
PAGE 8
LT1011/LT1011A U W U U APPLICATIONS INFORMATION The input resistors should limit fault current to a reasonable value (0.1mA to 20mA). Power dissipation in the resistors must be considered for continuous faults, especially when the LT1011 supplies are off. One final caution: lightly loaded supplies may be forced to higher voltages by large fault currents flowing through D1-D4.
PAGE 9
LT1011/LT1011A U W U U APPLICATIONS INFORMATION to V +, the voltage at the emitter in the “on” state is about 2V below V + (see curves). In the “off” state, I1 is switched off and both Q1 and Q2 turn off. The collector of Q2 can be now held at any voltage above V – without conducting current, including voltages above the positive supply level. Maximum voltage above V – is 50V for the LT1011M and 40V for the LT1011C/I.
PAGE 10
LT1011/LT1011A U TYPICAL APPLICATIONS Strobing Driving Ground Referred Load + 7 LT1011 3 V+ V ++** V+ 2 Window Detector – 2 INPUTS* 6 L1 4 V– 1k NOTE: DO NOT GROUND STROBE PIN – OUTPUT HIGH INSIDE “WINDOW” AND LOW ABOVE HIGH LIMIT OR BELOW LOW LIMIT 1 VIN 2 1011 TA07 *INPUT POLARITY IS REVERSED WHEN USING PIN 1 AS OUTPUT **V ++ MAY BE ANY VOLTAGE ABOVE V –.
PAGE 11
LT1011/LT1011A U TYPICAL APPLICATIONS Combining Offset Adjust and Strobe Combining Offset Adjustment and Hystersis V+ V+ 5k 10k RH* 2RH** 20k 5 – – TTL OR CMOS 5V 6 + LT1011 + 1k *HYSTERESIS IS ≈ 0.45mV/µA OF CURRENT CHANGE IN RH RL **THIS RESISTOR CAUSES HYSTERESIS TO BE CENTERED AROUND VOS 20k 6 5 7 LT1011 1011 TA15 1 1011 TA13 Direct Strobe Drive When CMOS* Logic Uses Same V + Supply as LT1011 Low Drift R/C Oscillator † V+ ** 8 – 6 + 15V 2 LT1011 C1 0.
PAGE 12
LT1011/LT1011A U TYPICAL APPLICATIONS 4-Digit (10,000 Count) A/D Converter 15V ZERO TRIM R1 1k 1 3 R2 18k INPUT 0V TO 10V C4 0.01µF 7 R3 3.9k 8 4 D1 D2 6 C1* 0.1µF C2** 15pF R6 4.7K 7 OUTPUT = 1 COUNT PER mV, f = 1MHz CLOCK 1MHz 1 – R7 22Ω 5V C5 0.01µF + 3 6 5V 8 LT1011 2 5 LF398 15V R5 4.7k 2 4 –15V 15V –15V R4 5.6k R8 3k D3 15V D4 C3 0.1µF R11 6.8K R10 1k R9 FULL-SCALE 3.65k TRIM R12 6.
PAGE 13
LT1011/LT1011A U TYPICAL APPLICATIONS Fast Settling* Filter 100pF 1M 15V 2 7 1M OUTPUT 8 3 VIN 1 4 4.7k –15V 15V 0.1µF 6 LT1008C 4.7k 1µF OFM-1A** –15V 100k 100pF 4 2 8 – 3 1.5k 7 1 LT1011 5 + 6 15V 15V 5k THRESHOLD 5k 6 + 5 1 LT1011 7 – 10k 8 4 –15V 15V 1011 TA21 100kHz Precision Rectifier 0.
PAGE 14
LT1011/LT1011A W W SCHE ATIC DIAGRA OFFSET OFFSET/STROBE V+ 5 6 8 R8 800Ω Q6 R27 3k R4 300Ω R5 160Ω R1 1.3k R2 1.3k Q10 R3 300Ω R23 4k Q11 Q5 Q31 Q12 R6 3.2k D1 D2 Q30 INPUT (+) R7 3.2k Q13 Q29 R11 170Ω D5 R12 470Ω Q4 Q27 R16 Q24 800Ω Q2 Q26 Q25 Q15 Q9 Q19 Q28 3 7 Q20 R22 200Ω Q1 D7 OUTPUT Q14 Q3 INPUT (–) R10 4k Q7 Q8 D4 D6 2 R9 800Ω Q21 Q23 Q16 R17 200Ω R24 400Ω R20 940Ω R13 4Ω R15 700Ω Q22 1 Q18 GND R25 1.6k R26 1.
PAGE 15
LT1011/LT1011A U PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted. J8 Package 8-Lead CERDIP (Narrow .300 Inch, Hermetic) (Reference LTC DWG # 05-08-1110) CORNER LEADS OPTION (4 PLCS) 0.405 (10.287) MAX 0.005 (0.127) MIN 0.023 – 0.045 (0.584 – 1.143) HALF LEAD OPTION 8 7 6 5 0.025 (0.635) RAD TYP 0.045 – 0.068 (1.143 – 1.727) FULL LEAD OPTION 0.220 – 0.310 (5.588 – 7.874) 1 2 3 0.300 BSC (0.762 BSC) 4 0.200 (5.080) MAX 0.015 – 0.060 (0.381 – 1.524) 0.008 – 0.
PAGE 16
LT1011/LT1011A U TYPICAL APPLICATION 10Hz to 100kHz Voltage to Frequency Converter R7 4.7k R4 1M 15V 15V C1 0.002µF POLYSTYRENE R1 4.7k LT1009 2.5V 15V INPUT 0V TO 10V R2 5k FULL-SCALE R3 TRIM 8.06k 3 C2 0.68µF 15V R16 50k 10Hz TRIM R5 2k 15V R8 4.7k 7 1 + R17† 22M LINEARITY ≈ 0.01% 8 – LT1011 2 R6 2k –15V 4 1.5µs 6 4.4V –15V 0.