Linear Technology LTC1688, LTC1689 Datasheet

FEATURES

■

Ultrahigh Speed:

■

Guaranteed Propagation Delay: 8ns ±4ns

100Mbps

Over Temperature

■

50Mbps Operation with VDD = 3V

■

Low Channel-to-Channel Skew: 500ps Typ

■

Low t

■

■

PLH/tPHL

Hot SwapTM Capable

Driver Outputs Maintain High Impedance in

Skew: 500ps Typ

Three-State or with Power Off

■

Short-Circuit Protected: 3mA Typ Output Current
for an Indefinite Short

■

Thermal Shutdown Protected

■

Single 5V or 3V Supply

■

Pin Compatible with LTC486/LTC487

U

APPLICATIO S

■

High Speed RS485 Twisted-Pair Drivers

■

High Speed Backplane Drivers

■

Complementary Clock Drivers

■

STS-1/OC-1 Data Drivers

■

SCSI Drivers

LTC1688/LTC1689

100Mbps RS485

Hot Swapable Quad Drivers

U

DESCRIPTIO

The LTC®1688/LTC1689 are ultrahigh speed, differential
bus/line drivers that can operate at data rates up to
100Mbps. Propagation delay is guaranteed at 8ns ±4ns
over the full operating temperature range. These devices
operate over the full RS485 common mode range (–7V
to 12V), and also meet RS422 requirements.

The driver outputs are Hot Swap capable, maintaining
backplane data integrity during board insertion and
removal. The drivers feature three-state outputs, maintain­ing high impedance over the entire common mode range
(–7V to 12V). Outputs also remain high impedance during
power-up and with the power off. A short-circuit feature
detects bus contention and substantially reduces driver
output current. Thermal shutdown circuitry protects the
parts from excessive power dissipation.

The LTC1688 allows all four drivers to be enabled together,
while the LTC1689 allows two drivers at a time to be
enabled.

The LTC1688/LTC1689 operate from a single 5V or 3V
supply and draw only 9mA of supply current.

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

Hot Swap is a trademark of Linear Technology Corporation.

TYPICAL APPLICATIO

50Mbps RS485 Data Connection

DRIVER

100 FT CATEGORY 5 UTP

1/4 LTC1688

U

20ns Pulse Across 100 Feet

of Category 5 UTP

2V/DIV

100Ω100Ω

RECEIVER

1/4 LTC1518

1688/89 TA01

2V/DIV

2V/DIV

5V/DIV

DRIVER INPUT

DRIVER OUTPUTS

CABLE DELAY

RECEIVER INPUT

RECEIVER OUTPUT

20ns/DIV

1688/89 TA02

1

LTC1688/LTC1689

A

W

O

LUTEXI TIS

S

A

WUW

U

ARB

G

PACKAGE

/

O

RDER I FOR ATIO

WU

(Note 1)

Supply Voltage (VDD)................................................ 7V

Enable Input Voltages................. –0.5V to (VDD + 0.5V)

Enable Input Currents..................... –100mA to 100mA

Driver Input Voltages.................. –0.5V to (VDD + 0.5V)

Driver Output Voltages ................. (–12V + VDD) to 12V

Driver Input Currents...................... –100mA to 100mA

Short-Circuit Duration (V

: –7V to 10V) ...... Indefinite

OUT

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

DI1
DO1A
DO1B

EN (EN12*)

DO2B
DO2A

DI2

GND

Consult factory for Industrial and Military grade parts.

The ● denotes the specifications which apply over the full operating

TOP VIEW

1
2
3
4
5
6
7
8

S PACKAGE

16-LEAD PLASTIC SO

*LTC1689 ONLY

T

= 150°C, θ

JMAX

JA

16
15
14
13
12
11
10

9

= 90°C/ W

V

DD

DI4
DO4A
DO4B
ENB (EN34*)
DO3B
DO3A
DI3

ORDER PART

NUMBER

LTC1688CS
LTC1689CS

temperature range, otherwise specifications are at TA = 25°C.

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VDD = 5V, Per Driver, TA = 25°C, Unless Otherwise Noted (Note 2)

V

OD1

V

OD2

∆V

OD

V

OC

∆VOC Change in Magnitude of Driver Common R = 25Ω or 50Ω, Figure 1 ● 0.2 V

V

IH

V

IL

I

IN1

I

OZ

I

DD

I

OSD1

I

OSD2

VDD = 3V, Per Driver, TA = 25°C, Unless Otherwise Noted (Note 2)

V

OD1

V

OD2

∆V

OD

V

OC

Differential Driver Output (Unloaded) I
Differential Driver Output (With Load) R = 50Ω (RS422) ● 2V

Change in Magnitude of Driver Differential R = 25Ω or 50Ω, Figure 1 ● 0.2 V
Output Voltage for Complementary
Output States

Driver Common Mode Output Voltage R = 25Ω or 50Ω, Figure 1 ● 23V

Mode Output Voltage for Complementary
Output States

Input High Voltage EN, ENB, EN12, EN34, DI ● 2V
Input Low Voltage EN, ENB, EN12, EN34, DI ● 0.8 V
Input Current EN, ENB, EN12, EN34, DI ● ±1 µA
Three-State (High Impedance) V

Output Current
Supply Current of Entire Device No Load, Digital Input Pins = 0V or V
Driver Short-Circuit Current, V
Driver Short-Circuit Current, V

Differential Driver Output (Unloaded) I
Differential Driver Output (With Load) R = 50Ω (RS422) 1.5 V

Change in Magnitude of Driver Differential R = 25Ω or 50Ω, Figure 1 0.1 V
Output Voltage for Complementary
Output States

Driver Common Mode Output Voltage R = 25Ω or 50Ω, Figure 1 1.3 V

= HIGH V

OUT

= LOW V

OUT

= 0 ● V

OUT

R = 25Ω (RS485), Figure 1

= –7V to 12V ● ±2 ±200 µA

OUT

DD

= –7V to 10V ● ±20 mA

OUT

= –7V to 10V ● ±20 mA

OUT

= 0 ● V

OUT

R = 25Ω (RS485), Figure 1

● 1.5 3.0 V

● 918 mA

● 0.65 2.0 V

DD

DD

U

V

V

2

LTC1688/LTC1689

DC ELECTRICAL CHARACTERISTICS

The ● denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at TA = 25°C.

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

∆VOC Change in Magnitude of Driver Common R = 25Ω or 50Ω, Figure 1 0.1 V

Mode Output Voltage for Complementary

Output States
V
V
I
I

IH

IL
IN1
OZ

Input High Voltage EN, ENB, EN12, EN34, DI ● 1.4 V
Input Low Voltage EN, ENB, EN12, EN34, DI ● 0.5 V
Input Current EN, ENB, EN12, EN34, DI (Note 3) ● ±1 µA
Three-State (High Impedance) V

= –7V to 10V (Note 3) ● ±1 ±200 µA

OUT

Output Current

I

DD

I

OSD1

I

OSD2

Supply Current of Entire Device No Load, Digital Input Pins = 0V or V
Driver Short-Circuit Current, V
Driver Short-Circuit Current, V

= HIGH V

OUT

= LOW V

OUT

= –7V to 8V (Note 3) ● ±20 mA

OUT

= –7V to 8V (Note 3) ● ±20 mA

OUT

DD

5mA

U

SWITCHING CHARACTERISTICS

temperature range, otherwise specifications are at TA = 25°C.

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VDD = 5V, TA = 25°C, Unless Otherwise Noted (Note 2)

t

, t

PLH

t

SKEW

tr, t

t

ZH

t

ZL

t

LZ

t

HZ

C

L(MAX)

VDD = 3V, TA = 25°C, Unless Otherwise Noted (Note 2)

t

PLH

t

SKEW

tr, t

t

ZH

t

ZL

t

LZ

t

HZ

C

L(MAX)

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

Driver Input-to-Output Propagation Delay R

PHL

Figures 2, 4

Driver Output-to-Output Skew R

Figures 2, 4

Driver Rise/Fall Time R

f

Figures 2, 4
Driver Enable to Output High CL = 25pF, S2 Closed, Figures 3, 5 ● 10 35 ns
Driver Enable to Output Low CL = 25pF, S1 Closed, Figures 3, 5 ● 10 35 ns
Driver Disable from Low CL = 15pF, S1 Closed, Figures 3, 5 ● 25 65 ns
Driver Disable from High CL = 15pF, S2 Closed, Figures 3, 5 ● 25 65 ns
Maximum Output Capacitive Load (Note 3) ● 200 pF
Maximum Data Rate (Note 3) ● 100 Mbps
Maximum Driver Input Rise/Fall Time (Note 3) ● 500 ns

, t

Driver Input-to-Output Propagation Delay R

PHL

Figures 2, 4
Driver Output-to-Output Skew R

Figures 2, 4
Driver Rise/Fall Time R

f

Figures 2, 4
Driver Enable to Output High CL = 25pF, S2 Closed, Figures 3, 5 25 ns
Driver Enable to Output Low CL = 25pF, S1 Closed, Figures 3, 5 25 ns
Driver Disable from Low CL = 15pF, S1 Closed, Figures 3, 5 50 ns
Driver Disable from High CL = 15pF, S2 Closed, Figures 3, 5 50 ns
Maximum Output Capacitive Load (Note 3) ● 200 pF
Maximum Data Rate 50 Mbps
Maximum Driver Input Rise/Fall Time (Note 3) ● 500 ns

The ● denotes the specifications which apply over the full operating

= 50Ω, CL1 = CL2 = 25pF, ● 4812 ns

DIFF

= 50Ω, CL1 = CL2 = 25pF, 500 ps

DIFF

= 50Ω, CL1 = CL2 = 25pF, 2 ns

DIFF

= 50Ω, CL1 = CL2 = 25pF, 11 ns

DIFF

= 50Ω, CL1 = CL2 = 25pF, 1 ns

DIFF

= 50Ω, CL1 = CL2 = 25pF, 4 ns

DIFF

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

Note 3: Guaranteed by design or correlation, but not tested.

3

LTC1688/LTC1689

UW

TYPICAL PERFORMANCE CHAR ACTERISTICS

Propagation Delay
vs Temperature

14

12

10

8

6

4

PROPAGATION DELAY (ns)

VDI = 0V TO 3V

= 50Ω

R

DIFF

2

= 25pF

C

L

0

0 20 40 60 80 100

TEMPERATURE (°C)

VDD = 3V

VDD = 5V

Supply Current vs Data Rate

250

200

4 DRIVERS

150

VDD = 5V

= 50Ω, PER DRIVER

R

DIFF

C

= 25pF, PER DRIVER

L

100

SUPPLY CURRENT (mA)

= 25°C

T

A

50

0

0 20 40 60 80 100 120

DATA RATE (Mbps)

SWITCHING

1 DRIVER
SWITCHING

1688/89 G01

1688/89 G03

Propagation Delay
vs Load Capacitance

14

12

10

8

6

4

PROPAGATION DELAY (ns)

VDI = 0V TO 3V

= 50Ω

R

DIFF

2

= 25°C

T

A

0

0 10 20 30 40 50 60

LOAD CAPACITANCE (pF)

VDD = 3V

VDD = 5V

Three-State Output Current

4.0
VDD = 5V

3.5

3.0

V

= –7V

2.5

2.0

1.5

OUTPUT CURRENT (µA)

1.0

0.5

0

0 20 40 60 80 100

OUT

V

TEMPERATURE (°C)

OUT

1688/89 G02

= 12V

1688/89 G04

4

vs Temperature

OD2

2.5

2.0

1.5

OD2

V

1.0

0.5
R

= 50Ω

DIFF

0

0 20 40 60 80 100

TEMPERATURE (°C)

VDD = 5V

VDD = 3V

1688/89 G05

IDD vs TemperatureV

180
160
140
120
100

(mA)

DD

I

80
60
40
20

0

4 DRIVERS LOADED

1 DRIVER LOADED

VDD = 5V

= 50Ω, PER DRIVER

R

DIFF

0.1Mbps

0 20 40 60 80 100

TEMPERATURE (°C)

1688/89 G06