Linear Technology LT1394 Datasheet

LT1394

7ns, Low Power,

Single Supply, Ground-Sensing

FEATURES

■

UltraFastTM: 7ns

■

Low Power: 6mA

■

Low Offset Voltage: 0.8mV

■

Operates Off Single 5V or Dual ±5V Supplies

■

Input Common Mode Extends to Negative Supply

■

No Minimum Input Slew Rate Requirement

■

Complementary TTL Outputs

■

Inputs Can Exceed Supplies without Phase Reversal

■

Pin Compatible with LT1016, LT1116 and LT1671

■

Output Latch Capability

■

Available in 8-Lead MSOP and SO Packages

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APPLICATIO S

■

High Speed A/D Converters

■

Zero-Crossing Detectors

■

Current Sense for Switching Regulators

■

Extended Range V/F Coverters

■

Fast Pulse Height/Width Discriminators

■

High Speed Triggers

■

Line Receivers

■

High Speed Sampling Circuits

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

UltraFast is a trademark of Linear Technology Corporation.

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Comparator

DESCRIPTIO

The LT®1394 is an UltraFast (7ns) comparator with comple­mentary outputs and latch. The input common mode range
extends from 1.5V below the positive supply down to the
negative supply rail. Like the LT1016, LT1116 and LT1671,
this comparator has complementary outputs designed to
interface directly to TTL or CMOS logic. The LT1394 may
operate from either a single 5V supply or dual ±5V supplies.
Low offset voltage specifications and high gain allow the
LT1394 to be used in precision applications.

The LT1394 is designed for improved speed and stability for
a wide range of operating conditions. The output stage
provides active drive in both directions for maximum speed
into TTL, CMOS or passive loads with minimal cross-conduc­tion current. Unlike other fast comparators, the LT1394
remains stable even for slow transitions through the active
region, which eliminates the need to specify a minimum input
slew rate.

The LT1394 has an internal, TTL/CMOS compatible latch for
retaining data at the outputs. The latch holds data as long as
the LATCH pin is held high. Device parameters such as gain,
offset and negative power supply current are not significantly
affected by variations in negative supply voltage.

TYPICAL APPLICATIO

45MHz Single Supply Adaptive Trigger

3

Q1 Q2

10µF

5V

+

A1

LT1227

–

750Ω

2k

5V

+

0.1µF

INPUT

510Ω

36Ω

+

100µF

0.1µF

2

13

Q3

15

2k

2k

1

0.005µF

14

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Propagation Delay vs

5V

6

5

3M

4

500pF

0.005µF

10

12

11

3M

Q4

+

LT1006

–

470Ω

5V

A2

0.1µF

Q1, Q2, Q3, Q4 = CA3096 ARRAY:
TIE SUBSTRATE (PIN 16) TO GROUND

470Ω

= 1N4148

+

LT1394

–

TRIGGER
OUT

1394 F18

12

10

8

6

TIME (ns)

4

2

0

Input Overdrive

TA = 25°C

= 100mV

V

STEP

= ±5V

V

S

0

10 20 30 40

OVERDRIVE (mV)

t

PDLH

t

PDHL

50

1394 TA02

1

LT1394

TOP VIEW

Q OUT
Q OUT
GND

V

+

+IN
–IN

V

–

S8 PACKAGE

8-LEAD PLASTIC SO

1

2

3

4

8

7

6

5

+
–

LATCH
ENABLE

WW

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ABSOLUTE MAXIMUM RATINGS

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(Note 1)

Total Supply Voltage (V+ to V–) ............................... 12V

Positive Supply Voltage ............................................. 7V

Negative Supply Voltage .......................................... –7V

Differential Input Voltage ....................................... ±12V

Input and Latch Current (Note 2)........................±10mA

Output Current (Continuous)(Note 2) .................±20mA

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PACKAGE/ORDER INFORMATION

TOP VIEW

+

V

1
2

+IN

3

–IN

–

4

V

MS8 PACKAGE

8-LEAD PLASTIC MSOP

T

= 150°C, θJA = 250°C/W

JMAX

8

Q OUT

7

Q OUT

6

GND

5

LATCH
ENABLE

ORDER PART

NUMBER

LT1394CMS8

MS8 PART MARKING

LTBH

Operating Temperature Range ................ –40°C to 85°C

Specified Temperature Range (Note 3)... –40°C to 85°C

Junction Temperature........................................... 150°C

Storage Temperature Range ................. –65°C to 150°C

Lead Temperature (Soldering, 10 sec).................. 300°C

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ORDER PART

NUMBER

LT1394CS8
LT1394IS8

S8 PART MARKING

T

= 150°C, θJA = 190°C/W

JMAX

1394
1394I

Consult factory for Military grade parts.

ELECTRICAL CHARACTERISTICS

The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C.
V+ = 5V, V– = –5V, V

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

OS

∆V

OS

∆T

I

OS

I

B

V

CMR

CMRR Common Mode Rejection Ratio –5V ≤ VCM ≤ 3.5V, TA > 0°C 55 100 dB

PSRR Power Supply Rejection Ratio 4.6V ≤ V+ ≤ 5.4V ● 50 65 dB

A

V

V

OH

2

Input Offset Voltage RS ≤ 100Ω (Note 4) 0.8 2.5 mV

Input Offset Voltage Drift ● 4 µV/°C

Input Offset Current 0.1 0.5 µA

Input Bias Current (Note 5) 2 4.5 µA

Input Voltage Range (Note 6) ● –5 3.5 V

Small Signal Voltage Gain 1V ≤ V
Output Voltage Swing High V+ ≥ 4.6V, I

(Q) = 1.4V, V

OUT

= VCM = 0V unless otherwise noted.

LATCH

Single 5V Supply

–5V ≤ V
Single 5V Supply

0V ≤ V
0V ≤ V

–7V ≤ V

+

V

≤ 3.3V, TA ≤ 0°C55 dB

CM

≤ 3.5V, TA > 0°C 55 100 dB

CM

≤ 3.3V, TA ≤ 0°C55 dB

CM

–

≤ –2V ● 65 100 dB

≤ 2V 750 1600 V/V

OUT

≥ 4.6V, I

OUT
OUT

● 4.0 mV

● 0.8 µA

● 7.0 µA

● 0 3.5 V

= 1mA ● 2.7 3.1 V
= 4mA ● 2.4 3.0 V

LT1394

ELECTRICAL CHARACTERISTICS

The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C.
V+ = 5V, V– = –5V, V

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

OL

+

I

–

I

V

IH

V

IL

I

IL

t

PD

∆t

PD

t

LPD

t

SU

t

H

t

PW(D)

Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.

Note 2: This parameter is guaranteed to meet specified perforamnce
through design and characterization. It has not been tested.

Note 3: The LT1394CMS8 and LT1394CS8 are guaranteed to meet
specified performance from 0°C to 70°C and are designed, characterized
and expected to meet these extended temperature limits, but are not tested
at –40°C and 85°C. The LT1394IS8 is guaranteed to meet the extended
temperature limits.

Note 4: Input offset voltage (V
voltages measured by forcing first one output, then the other to 1.4V.

Note 5: Input bias current (I
currents.

Note 6: Input voltage range is guaranteed in part by CMRR testing and in
part by design and characterization.

Output Voltage Swing Low I

Positive Supply Current 6 8.5 mA

Negative Supply Current 1.2 2.2 mA

LATCH Pin High Input Voltage ● 2V
LATCH Pin Low Input Voltage ● 0.8 V
LATCH Pin Current V
Propagation Delay (Note 7) ∆VIN = 100mV, VOD = 5mV 7 9 ns

Differential Propagation Delay (Note 7) ∆VIN = 100mV, VOD = 5mV 0.5 2.2 ns
Latch Propagation Delay (Note 8) 6 ns
Latch Setup Time (Note 8) –0.4 ns
Latch Hold Time (Note 8) 2ns
Minimum Disable Pulse Width 3ns

(Q) = 1.4V, V

OUT

) is defined as the average of the two

OS

) is defined as the average of the two input

B

= VCM = 0V unless otherwise noted.

LATCH

= –4mA ● 0.3 0.5 V

OUT

I

= –10mA 0.4 V

OUT

● 10.0 mA

● 2.5 mA

= 0V ● –4 –10 µA

LATCH

● 14 ns

Note 7: t

and ∆tPD cannot be measured in automatic handling

PD

equipment with low values of overdrive. The LT1394 is 100% tested with a
100mV step and 20mV overdrive. Correlation tests have shown that t
and ∆tPD limits can be guaranteed with this test, if additional DC tests are
performed to guarantee that all internal bias conditions are correct.
Propagation delay (tPD) is measured with the overdrive added to the actual

. Differential propagation delay is defined as:

V

OS

∆tPD = t

Note 8: Latch propagation delay (t
respond when the LATCH pin is deasserted. Latch setup time (t

PDLH

– t

PDHL

) is the delay time for the output to

LPD

SU

interval in which the input signal must remain stable prior to asserting the
latch signal. Latch hold time (tH) is the interval after the latch is asserted in
which the input signal must remain stable.

PD

) is the

3

LT1394

POSITIVE SUPPLY VOLTAGE (V)

4.4

TIME (ns)

12

10

8

6

4

2

0

4.6 4.8 5.0 5.2 5.4

1394 G03

5.6

t

PDHL

t

PDLH

V– = –5V
T

A

= 25°C

V

STEP

= 100mV

OVERDRIVE = 5mV

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TYPICAL PERFORMANCE CHARACTERISTICS

Gain Characteristics

5.0

4.5

4.0

3.5

3.0

2.5

2.0

1.5

OUTPUT VOLTAGE (V)

1.0

0.5
0

TA = 125°C

TA = 25°C

TA = –55°C

–3

–2

–1

DIFFERENTIAL INPUT VOLTAGE (mV)

Propagation Delay vs
Input Overdrive

12

TA = 25°C

= 100mV

V

STEP

10

= ±5V

V

S

8

6

TIME (ns)

4

2

0

10 20 30 40

0

OVERDRIVE (mV)

01

t

PDLH

t

PDHL

VS = ±5V

= 0

I

OUT

2

1394 G01

1394 TA02

Propagation Delay vs
Load Capacitance

12

10

8

6

TIME (ns)

4

I

= 0

OUT

V

= ±5V

S

= 25°C

T

A

2

= 100mV

V

STEP

OVERDRIVE = 5mV

0

10 20 30 40

3

0

OUTPUT LOAD CAPACITANCE (pF)

t

PDLH

t

PDHL

50

1394 G02

Propagation Delay vs
Source Resistance

80

70

60

50

40

TIME (ns)

50

30

20

10

0

0 0.5

STEP SIZE = 800mV

1.0 2.01.5

SOURCE RESISTANCE (kΩ)

400mV

100mV

VS = ±5V

= 20mV

V

OD

= 25°C

T

A

200mV

2.5

3.0

1394 G04

Propagation Delay vs
Positive Supply Voltage

Propagation Delay vs
Temperature

12

VS = ±5V

= 100mV

V

STEP

10

= 5mV

V

OD

8

6

TIME (ns)

4

2

0

–50

–25 0

TEMPERATURE (°C)

t

PDLH

t

PDHL

50 100 125

25 75

1394 G05

Input Offset Voltage vs
Temperature

2

VS = ±5V

1

0

–1

–2

VOLTAGE (mV)

–3

–4

–5

–50 25 75

–25 0

TEMPERATURE (°C)

4

50 100 125

LT1394 G06

Input Bias Current vs
Temperature

4

VS = ±5V

3

2

1

INPUT BIAS CURRENT (µA)

0

–50 25 75

–25 0

VCM = –5V

VCM = 0V

VCM = 3.5V

TEMPERATURE (°C)

50 100 125

LT1394 G07

Positive Common Mode Limit vs
Temperature

6

VS = ±5V

5

4

3

VOLTAGE (V)

2

1

0

–50

–25 0

TEMPERATURE (°C)

50 100 125

25 75

1394 G08

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TYPICAL PERFORMANCE CHARACTERISTICS

LT1394

Negative Common Mode Limit vs
Temperature

1

0

–1

–2

–3

INPUT VOLTAGE (V)

–4

–5

–6

–50 25 75

–25 0

VS = SINGLE 5V

VS = ±5V

50 100 125

TEMPERATURE (°C)

Positive Supply Current vs
V+ Supply Voltage

10

V– = 0V

9

= –60mV

V

IN

= 0

I

8

OUT

7
6

TA = 125°C

5
4

TA = 25°C

CURRENT (mA)

3
2
1
0

0

13

2

TA = –55°C

4

SUPPLY VOLTAGE (V)

5

Output Low Voltage (VOL) vs
Output Sink Current

0.8
VS = ±5V

LT1394 G09

0.7

0.6

0.5

0.4

VOLTAGE (V)

0.3

0.2

0.1

= 30mV

∆V

IN

TA = 125°C

TA = –55°C

0

02 6 10 14

4

OUTPUT SINK CURRENT (mA)

TA = 25°C

8

12

16

1394 G10

Positive Supply Current vs
Switching Frequency

16

VS = ±5V

14

12

10

TA = 125°C

8

6

CURRENT (mA)

TA = –55°C

4

2

0

7

6

8

1394 G12

1

SWITCHING FREQUENCY (MHz)

TA = 25°C

10 100

1394 G13

Output High Voltage (VOH) vs
Output Source Current

5.0
VS = ±5V

4.5

4.0

3.5

3.0

2.5

OUTPUT VOLTAGE (V)

2.0

1.5

1.0

= –30mV

∆V

IN

TA = 125°C

TA = 25°C

TA = –55°C

02 6 10 14

4

OUTPUT SOURCE CURRENT (mA)

8

Negative Supply Current vs
V– Supply Voltage

4

+

V

= 5V

∆V

= –60mV

IN

3

2

CURRENT (mA)

1

0

–7 –5 –3

–8

TA = 125°C

TA = 25°C

TA = –55°C

–6

NEGATIVE SUPPLY VOLTAGE (V)

–4

–1

16

1394 G11

0

1394 G14

12

–2

Latch Pin Current vs Temperature

8

VS = ±5V

7

6

5

4

3

CURRENT (µA)

2

1

0

= 0V

V

LATCH

–50 25 75

–25 0

TEMPERATURE (°C)

50 100 125

LT1394 G15

Response to 100MHz ±10mV

Sine Wave

+IN

20mV

P-P

3V

Q

OUT

0V

FET PROBES 5ns/DIV

10mV/DIV

1V/DIV

1394 G16

5