Linear Technology LTC1520 Datasheet

Final Electrical Specifications

LTC1520

50Mbps Precision Quad

Line Receiver

FEATURES

■

Precision Propagation Delay: 18ns ±3ns Over
Temperature

■

Data Rate: 50Mbps

■

Low t

■

■

■

■

■

■

■

■

■

PLH/tPHL

Low Channel-to-Channel Skew: 400ps Typ

Rail-to-Rail Input Common Mode Range
High Input Resistance: ≥18k, Even When Unpowered
Hot Swap Capable
Can Withstand Input DC Levels of ±10V
Short-Circuit Protected
Single 5V Supply
LVDS Compatible
Will Not Oscillate with Slow Input Signals

Skew: 500ps Typ

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APPLICATIONS

■

High Speed Backplane Interface

■

Line Collision Detector

■

PECL and LVDS Line Receivers

■

Level Translator

■

Ring Oscillator

■

Tapped Delay Line

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

U

May 1996

DESCRIPTION

The LTC®1520 is a high speed, precision differential line
receiver that can operate at data rates as high as 50Mbps.
A unique architecture provides very stable propagation
delays and low skew over a wide input common mode,
input overdrive and ambient temperature range. Propaga­tion delay is 18ns ± 3ns, while typically t

PLH/tPHL

500ps and channel-to-channel skew is 400ps.
Each receiver translates differential input levels (VID ≥

100mV) into valid CMOS and TTL output levels. Its high
input resistance (≥18k) allows many receivers to be con­nected to the same driver. The receiver outputs go into a
high impedance state when disabled.

Protection features include thermal shutdown and a con­trolled maximum short-circuit current (50mA max) that
does not oscillate in and out of short-circuit mode. Input
resistance remains ≥18k when the device is unpowered or
disabled, thus allowing the LTC1520 to be hot swapped into
a backplane without loading the data lines.

The LTC1520 operates from a single 5V supply and draws
12mA of supply current. The part is available in a 16-lead
narrow SO package.

skew is

TYPICAL APPLICATION

High Speed Backplane Receiver

LTC1520

+

–

+

–

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen­tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.

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+

–

+

–

Propagation Delay Guaranteed to Fall

Within Shaded Area (±3ns)

RECEIVER

VIN =

1V/DIV

RECEIVER

OUTPUT

=

V

OUT

5V/DIV

5V

3.3k

3.3k

0.01µF

LTC1520 TA01

= 5V

V

DD

–5 5 15

TIME (ns)

INPUT

V

= 500mV

ID

25 350 1020304045

LTC1520 TA02

1

LTC1520

A

W

O

LUTEXI T

S

A

WUW

ARB

U
G

I

S

(Note 1)

Supply Voltage ....................................................... 10V

Digital Input Currents ..................... –100mA to 100mA

Digital Input Voltages ............................... –0.5V to 10V

Receiver Input Voltages ........................................ ±10V

Receiver Output Voltages ............. – 0.5V to VDD + 0.5V

Short-Circuit Duration .................................... Indefinite

Operating Temperature Range .................... 0°C to 70°C

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

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

DC ELECTRICAL CHARACTERISTICS

VDD = 5V (Notes 2, 3) per receiver, unless otherwise noted.

/

TOP VIEW

S PACKAGE

= 150°C, θ

O

RDER I FOR ATIO

ORDER PART

16

V



DD

15

B4

LTC1520CS

= 90°C/W

JA

14

A4

13

OUT 4

12

NC

11

OUT 3

10

A3

9

B3

PACKAGE

1

B1

2

A1

3

OUT 1

4

ENABLE

5

OUT 2

6

A2

7

B2

8

GND

16-LEAD PLASTIC SO

T

JMAX

Consult factory for Industrial and Military grade parts.

WU

U

NUMBER

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

CM

V

IH

V

IL

I

IN1

I

IN2

R

IN

C

IN

V

OC

V

ID(MIN)

dV

ID

V

OH

V

OL

I

OZR

I

DD

I

OSR

CMRR Common Mode Rejection Ratio VCM = 2.5V, f = 25MHz 45 dB

Input Common Mode Voltage A, B Inputs ● –0.2 VDD + 0.2 V
Input High Voltage Enable Input ● 2V
Input Low Voltage Enable Input ● 0.8 V
Input Current Enable Input ● –1 1 µA
Input Current (A, B) VA, VB = 5V ● 250 µA

, VB = 0 ● –250 µA

V

A

Input Resistance (Figure 5) –0.2V ≤ VCM ≤ VDD + 0.2V ● 18 kΩ
A, B Input Capacitance 3pF
Open-Circuit Input Voltage (Figure 5) VDD = 5V (Note 4) ● 3.2 3.3 3.4 V
Differential Input Threshold Voltage –0.2V < VCM < VDD + 0.2V ● –0.1 0.1 V
Input Hysteresis VCM = 2.5V ● 20 mV
Output High Voltage I
Output Low Voltage I
Three-State Output Current 0V ≤ V
Total Supply Current All 4 Receivers VID ≥ 0.1V, No Load, Enable = 5V ● 12 20 mA
Short-Circuit Current V

= –4mA, VID = 0.1V, VDD = 5V ● 4.6 V

OUT

= 4mA, VID = 0.1V, VDD = 5V ● 0.4 V

OUT

≤ 5V ● –10 10 µA

OUT

OUT

= 0V, V

= 5V ● –50 50 mA

OUT

2

LTC1520

UW

SWITCHI G TI E CHARACTERISTICS

VDD = 5V (Notes 2, 3) VID = 500mV, VCM = 2.5V, unless otherwise noted.

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

t

, t

PLH

tr, t

f

t

SKD

t

ZL

t

ZH

t

LZ

t

HZ

t

CH-CH

t

PKG-PKG

f

IN

Input-to-Output Propagation Delay CL = 15pF (Figure 1) ● 15 18 21 ns

PHL

Rise/Fall Times CL = 15pF 2.5 ns

t

– t

PLH

 Skew C

PHL

= 15pF, Same Receiver (Note 5) ● 500 ps

L

Enable to Output Low CL = 15pF (Figure 2) ● 10 25 ns
Enable to Output High CL = 15pF (Figure 2) ● 10 25 ns
Disable from Output Low CL = 15pF (Figure 2) ● 20 35 ns
Disable from Output High CL = 15pF (Figure 2) ● 20 35 ns
Channel-to-Channel Skew CL = 15pF (Figure 3) (Note 6) ● 400 ps
Package-to-Package Skew CL = 15pF, Same Temperature 1.5 ns

(Figure 4, Note 4)
Minimum Input Pulse Width (Note 4) 12 ns
Maximum Input Frequency (Note 4) 40 MHz

The ● denotes specifications which apply over the full operating
temperature range.

Note 1: Absolute Maximum Ratings are those values beyond which the
safety of the device cannot be guaranteed. Recommended: V

= 5V ±5%.

DD

Note 2: All currents into the device pins are positive; all currents out of the
device pins are negative.

W

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Note 3: All typicals are given for V
Note 4: Guaranteed by design, but not tested.
Note 5: Worst-case t

over the full operating temperature range.
Note 6: Maximum difference between any two t

single package over the full operating temperature range.

TYPICAL PERFORMANCE CHARACTERISTICS

Propagation Delay (t
vs Temperature

25

VCM = 2.5V

= 500mV

V

ID

20

15

10

PROPAGATION DELAY (ns)

5

PLH/tPHL

)

– t

PLH

 skew for a single receiver in a package

PHL

Propagation Delay (t
vs Input Overdrive

25

20

15

10

PROPAGATION DELAY (ns)

5

= 5V, TA = 25°C.

DD

PLH/tPHL

TA = 25°C
V

PLH

CM

or t

)

= 2.5V

transitions in a

PHL

0

–50 –25

0

TEMPERATURE (°C)

50

25

100

LTC1520 G01

125

75

0

0.05

0.1 1 5 10
INPUT OVERDRIVE (V)

1520 G02

3