Datasheet

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LTC1518/LTC1519

52Mbps Precision Delay

RS485 Quad Line Receivers

■

Precision Propagation Delay: 18.5ns ±3.5ns Over

0°C to 70°C Temperature Range

■

High Data Rate:

52Mbps

■

Low t

PLH

PHL

Skew: 500ps Typ

■

Low Channel-to-Channel Skew: 500ps Typ

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Guaranteed Fail-Safe Operation over the Entire

Common Mode Range

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–7V to 12V RS485 Input Common Mode Range

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Input Resistance ≥22k, Even When Unpowered

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Hot Swap

Capable

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High Common Mode Rejection to 26MHz

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Short-Circuit Protection: 10mA Typ Output Current

for an Indefinite Short

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Three-State Output Capability

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Will Not Oscillate with Slow Moving Input Signals

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Single 5V Supply

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Pin Compatible with LTC488, LTC489

The LTC

1518/LTC1519 are high speed, precision delay

differential quad bus/line receivers that can operate at data

rates as high as 52Mbps. They are pin compatible with the

LTC488/LTC489 RS485 line receivers and operate over the

entire –7V to 12V common mode range. A unique architec-

ture provides very stable propagation delays and low skew

over wide input common mode, input overdrive and ambi-

ent temperature ranges. Propagation delay is 18.5ns ±3.5ns

over the commercial temperature range. Typical t

PLH

PHL

and channel-to-channel skew is 500ps.

Each receiver translates differential input levels (V

 ≥

300mV) into valid CMOS and TTL output levels. Its high

input resistance (≥22k) allows many receivers to be con-

nected to the same driver. The receiver outputs go into a

high impedance state when disabled.

The receivers have a fail-safe feature that guarantees a high

output state when the inputs are shorted or left floating.

Other protection features include thermal shutdown and a

controlled maximum short-circuit current (50mA Max).

Input resistance remains ≥22k when the device is

unpowered or disabled, thus allowing hot swapping with-

out loading the data lines.

The LTC1518/LTC1519 operate from a single 5V supply

and draw 12mA of supply current.

■

High Speed RS485/RS422 Receivers

■

STS-1/OC-1 Data Receivers

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PECL Line Receivers

■

Level Translators

■

Fast-20/Fast-40 SCSI Receiver

Propagation Delay Guaranteed to Fall

Within Shaded Area (±3.5ns)

52Mbps Data Communication over Twisted Pair

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

Hot Swap is a trademark of Linear Technology Corporation.

FEATURES

DESCRIPTIO

APPLICATIO S

TYPICAL APPLICATIO

1518/19 TA02

3V/DIV

OUT

5V/DIV

–5 5 15

TIME (ns)

25 350 1020304045

RECEIVER

INPUT

= 1.5V

RECEIVER

OUTPUT

= 5V

= 0°C TO 70°C

100Ω

A 1

1518/19 F08

1/4 LTC1518 LTC1685LTC1685

2 B

100Ω

RE RE

Summary of content (12 pages)

PAGE 1
LTC1518/LTC1519 52Mbps Precision Delay RS485 Quad Line Receivers U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO Precision Propagation Delay: 18.5ns ±3.
PAGE 2
LTC1518/LTC1519 W W W AXI U U ABSOLUTE RATI GS (Note 1) Supply Voltage ....................................................... 10V Digital Input Currents ..................... – 100mA to 100mA Digital Input Voltages ............................... – 0.5V to 10V Receiver Input Voltages ........................................ ±14V Receiver Output Voltages ............. – 0.5V to VDD + 0.5V Receiver Input Differential ....................................... 10V Short-Circuit Duration ................
PAGE 3
LTC1518/LTC1519 DC ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VDD = 5V ±5% (Notes 2, 3) per receiver, unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN Max VID for Fail-Safe Detection –7V ≤ VCM ≤ 12V 25 2 µs VCM = 2.
PAGE 4
LTC1518/LTC1519 U W TYPICAL PERFOR A CE CHARACTERISTICS Propagation Delay (tPLH/tPHL) vs Temperature CMRR vs Frequency 45.0 44.5 44.0 43.5 43.0 TA = 25°C VCM = 2.5V 42.5 1k 20 40 15 10 5 100k FREQUENCY (Hz) 10M 50 25 0 75 TEMPERATURE (°C) 100 15 100°C 25°C 0°C –25°C –50°C 50 20 15 10 20 15 10 5 0 5 15 25 35 55 105 LOAD CAPACITANCE (pF) 205 –6 –4 –2 8 0 4 6 2 COMMON MODE (V) 15189 G05 Propagation Delay vs Input Differential Voltage 70 TA = 25°C VCM = 2.
PAGE 5
LTC1518/LTC1519 U U U PI FU CTIO S LTC1518 LTC1519 B1 (Pin 1): Receiver 1 Inverting Input. B1 (Pin 1): Receiver 1 Inverting Input. A1 (Pin 2): Receiver 1 Noninverting Input. A1 (Pin 2): Receiver 1 Noninverting Input. OUT 1 (Pin 3): Receiver 1 Output. OUT 1 (Pin 3): Receiver 1 Output. EN (Pin 4): A high enables all outputs; a low on Pin 4 and a high on Pin 12 will put all outputs into a high impedance state. Do not float.
PAGE 6
LTC1518/LTC1519 U W W SWITCHI G TI E WAVEFOR S t r = t f ≤ 3ns for all input and enable signals. 3V + INPUT 1.5V 0V 1/4 LTC1518 LTC1519 5V 15pF t LZ t ZL OUTPUT – 2.5V 1.5V ENABLE OUT 1 2.5V OUTPUT NORMALLY LOW 2.5V OUTPUT NORMALLY HIGH VOL 1518/19 F01b VOH OUT 1 0V 4V 2.5V INPUT OUTPUT t HZ 1V S1 RECEIVER OUTPUT t PHL VDD/2 1k Figure 1. Propagation Delay Test Circuit and Waveforms Figure 2. Receiver Enable and Disable Timing Test Circuit and Waveforms 4V 1V B1, B2 = 2.
PAGE 7
LTC1518/LTC1519 U U EQUIVALE T I PUT NETWORKS ≥ 22k ≥ 22k A 3.3V A ≥ 22k ≥ 22k B 3.3V RECEIVER ENABLED, VDD = 5V B RECEIVER DISABLED OR VDD = 0V 1518/19 F05 Figure 5.
PAGE 8
LTC1518/LTC1519 U W U U APPLICATIO S I FOR ATIO When the inputs are accidentally shorted (by cutting through a cable, for example), the short-circuit fail-safe feature will guarantee a high output logic level. Note also that if the line driver is removed and the termination resistors are left in place, the receiver will see this as a “short” and output a logic high. Both of these fail-safe features will keep the receiver from outputting false data pulses under fault conditions.
PAGE 9
LTC1518/LTC1519 U W U U APPLICATIO S I FOR ATIO Note that due to the increased skew, this configuration might not operate at the highest data rates. To transmit single-ended data over short to medium distances, twisted pair is recommended with the unused wire grounded at both ends (Figure 7). Differential Transmission Data rates up to 52Mbps can be transmitted over 100 feet of high quality category 5 twisted pair. Figure 8 shows the LTC1518 receiving differential data from an LTC1685 transceiver.
PAGE 10
LTC1518/LTC1519 U W U U APPLICATIO S I FOR ATIO Figure 9 shows a trace with 100ft category 5 UTP between an LTC1685 driver and an LTC1518 receiver. Notice that at the far end of the cable, the signal to the LTC1518 input has been reduced. Figure 10 shows a 52Mbps square wave. Output Short-Circuit Protection The LTC1518/LTC1519 employ voltage sensing shortcircuit protection at the output terminals.
PAGE 11
LTC1518/LTC1519 U PACKAGE DESCRIPTIO Dimensions in inches (millimeters) unless otherwise noted. S Package 16-Lead Plastic Small Outline (Narrow 0.150) (LTC DWG # 05-08-1610) 0.386 – 0.394* (9.804 – 10.008) 16 15 14 13 12 11 10 9 0.150 – 0.157** (3.810 – 3.988) 0.228 – 0.244 (5.791 – 6.197) 1 0.010 – 0.020 × 45° (0.254 – 0.508) 2 3 4 5 6 0.053 – 0.069 (1.346 – 1.752) 0.008 – 0.010 (0.203 – 0.254) 0.014 – 0.019 (0.355 – 0.483) TYP 8 0.004 – 0.010 (0.101 – 0.254) 0° – 8° TYP 0.
PAGE 12
LTC1518/LTC1519 U TYPICAL APPLICATIO High Speed Receiver with Hot Swap Control BACK PLANE PLUG-IN CARD R1 0.005Ω Q1 MTB56N06V VCC 5V 5A VCC + R3 6.81k 1% R2 10Ω 5% 8 2 SENSE VCC C1 0.1µF 6 GATE FB ON CONNECTOR 1 CONNECTOR 2 ON/RESET 7 R4 2.43k 1% 5 µP LTC1422 RESET TIMER C4 2200µF 1 RESET GND 3 4 C2 0.33µF 3.3k GND 8 DATA BUS 2 LTC1518 + 1 – 6 + 7 – 10 + 9 – 14 + 15 – 16 4 3 5 3.3k 0.