LINER LTC1324CN

LTC1324
Single Supply LocalTalk®
Transceiver
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DESCRIPTION
FEATURES
■
■
■
■
■
■
■
Single Chip 5V LocalTalk Port
Low Power: ICC = 1mA Typ
Shutdown Pin Reduces ICC to 1µA Typ
Digitally Selectable Low Slew Rate Mode for
Reduced EMI Emmisions
Drivers Maintain High Impedance in Three-State or
with Power Off
Thermal Shutdown Protection
Drivers Are Short-Circuit Protected
The LTC®1324 is a single 5V line transceiver designed to
operate on Apple®LocalTalk networks. The driver features
a digitally selectable low slew rate mode for reduced EMI
emissions. The chip draws only 1mA quiescent current
when active and 1µA in shutdown. The differential driver
outputs three-state when disabled, during shutdown or
when the power is off. The driver outputs will maintain
high impedance even with output common mode voltages
beyond the power supply rails. Both the driver outputs and
receiver inputs are protected against ESD damage to
±10kV.
LocalTalk Peripherals
Notebook and Palmtop Computers
Battery-Powered Systems
The LTC1324 is available in a 16-pin SO Wide package.
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APPLICATIONS
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, LTC and LT are registered trademarks of Linear Technology Corporation.
Apple and LocalTalk are registered trademarks of Apple Computer, Inc.
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TYPICAL APPLICATION
Waveform of Driver
Typical LocalTalk Connection for Low EMI
5V
16
SLEW RATE CONTROL
DATA IN
TX ENABLE
SHUTDOWN
RX ENABLE
DATA OUT
12
2
3
6
DIN
5V/DIV
120Ω
11
4
5
LocalTalk
TRANSFORMER
DOUT
1V/DIV
LTC1324
10
7
8
9
1324 TA01
TIME (0.5µs/DIV)
1324 TA02
1
LTC1324
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ABSOLUTE MAXIMUM RATINGS
PACKAGE/ORDER INFORMATION
(Note 1)
Supply Voltage (VCC) ................................................ 7V
Input Voltage (Logic Inputs) ........ – 0.3V to (VCC + 0.3V)
Input Voltage (Receiver Inputs) ............................ ±1 5V
Driver Output Voltage (Forced) ............................. ±15V
Driver 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
ORDER PART
NUMBER
TOP VIEW
NC 1
16 VCC
SR 2
15 TXDEN
14 RXEN
TXD 3
TXDEN 4
SHDN 5
12 TXD –
RXEN 6
11 TXD +
RXO 7
10 RXD –
RX
9
GND 8
N PACKAGE
16-LEAD PDIP
LTC1324CN
LTC1324CSW
13 NC
DX
RXD +
SW PACKAGE
16-LEAD PLASTIC SO WIDE
TJMAX = 150°C, θJA = 110°C/ W (N)
TJMAX = 150°C, θJA = 150°C/ W (SW)
Consult factory for Industrial and Military grade parts.
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER
VCC = 5V, TA = 0°C to 70°C (Notes 2, 3), unless otherwise noted.
CONDITIONS
MIN
TYP
MAX
1
1
2
10
UNITS
Supplies
ICC
Normal Operation Supply Current
Shutdown Supply Current
No Load, SHDN = 0V, TXDEN = 0V, RXEN = 0V
No Load, SHDN = VCC
●
●
●
●
mA
µA
Differential Driver
±4.0
±2.0
VOD
Differential Output Voltage
No Load
RL = 50Ω (Figure 1)
∆VOD
Change in Magnitude of Differential
Output Voltage
RL = 50Ω (Figure 1)
0.2
V
VOC
Differential Common Mode Output Voltage
RL = 50Ω (Figure 1)
3.0
V
ISS
Short-Circuit Current
0V ≤ VO ≤ 5V
●
IOZ
Three-State Output Current
(TXDEN = VCC and TXDEN = GND) or
SHDN = VCC or Power Off, – 10V ≤ VO ≤ 10V
●
35
V
V
120
250
mA
±2
±200
µA
Logic Inputs
VIH
Input High Voltage
All Logic Input Pins
●
VIL
Input Low Voltage
All Logic Input Pins
●
IIN
Input Current
SHDN, TXDEN, RXDEN, V = 0V to VCC
●
IDN
Pull-Down Current
RXDEN, TXDEN, SR, V = 0V to VCC
●
2.4
V
0.8
V
±1
±20
µA
15
60
µA
Receiver
Input Resistance
– 7V ≤ VIN ≤ 7V
Receiver Threshold Voltage
– 7V ≤ VCM ≤ 7V
Receiver Input Hysteresis
– 7V ≤ VCM ≤ 7V
VOH
Output High Voltage
IO = – 4mA
●
VOL
Output Low Voltage
IO = 4mA
●
ISS
Output Short-Circuit Current
0V ≤ VO ≤ 5V
●
IOZ
Output Three-State Current
0V ≤ VO ≤ 5V, RXEN = VCC, RXEN = GND
●
RIN
2
12
●
kΩ
– 200
200
70
mV
mV
3.5
V
7
±2
0.4
V
85
mA
±100
µA
LTC1324
ELECTRICAL CHARACTERISTICS
SYMBOL
PARAMETER
VCC = 5V, TA = 0°C to 70°C (Notes 2, 3), unless otherwise noted.
CONDITIONS
MIN
TYP
MAX
UNITS
Switching Characteristics
tPLH, tPHL
tSKEW
t r, t f
t Hdis, t Ldis
t ENH, t ENL
Driver Propagation Delay
Without Slew Rate Control
RL = 100Ω, CL = 100pF (Figures 2, 4)
SR = GND
●
40
120
ns
Driver Propagation Delay
with Slew Rate Control
RL = 100Ω, CL = 100pF (Figures 2, 4)
SR = VCC
●
0.4
1.2
µs
Receiver Propagation Delay
CL = 15pF (Figures 2, 6)
●
40
120
ns
Driver Output to Output
Without Slew Rate Control
RL = 100Ω, CL = 100pF (Figures 2, 4)
SR = GND
●
10
35
ns
Driver Output to Output
with Slew Rate Control
RL = 100Ω, CL = 100pF (Figures 2, 4)
SR = VCC
●
25
100
ns
Driver Rise/Fall Time
Without Slew Rate Control
RL = 100Ω, CL = 100pF (Figures 2,4)
SR = GND
●
20
50
ns
Driver Rise/Fall Time
with Slew Rate Control
RL = 100Ω, CL = 100pF (Figures 2, 4)
SR = VCC
●
0.4
1.2
µs
Driver Output Active to Disable
Without Slew Rate Control
CL = 15pF (Figures 3, 5)
SR = GND
●
50
150
ns
Driver Output Active to Disable
with Slew Rate Control
CL = 15pF (Figures 3, 5)
SR = VCC
●
0.7
2
µs
Receiver Output Active to Disable
CL = 15pF (Figures 3, 7)
●
30
100
ns
Driver Enable to Output Active
Without Slew Rate Control
CL = 15pF (Figures 3, 5)
SR = GND
●
50
150
ns
Driver Enable to Output Active
with Slew Rate Control
CL = 15pF (Figures 3, 5)
SR = VCC
●
250
750
ns
Receiver Enable to Output Active
CL = 15pF (Figures 3, 7)
●
30
100
ns
The ● denotes specifications which apply over the full operating
temperature range.
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: All currents into device pins are positive and all currents out of
device pins are negative. All voltages are reference to ground unless
otherwise specified.
Note 3: All typicals are given at VCC = 5V, TA = 25°C.
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TYPICAL PERFORMANCE CHARACTERISTICS
Driver Differential Output Voltage
vs Output Current
Driver Output Low Voltage
vs Output Current
120
80
TA = 25°C
–90
50
40
30
20
OUTPUT CURRENT (mA)
100
60
80
60
40
20
10
0
–105
TA = 25°C
TA = 25°C
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
70
Driver Output High Voltage
vs Output Current
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
DRIVER DIFFERENTIAL OUTPUT VOLTAGE (V)
1324 G01
0
–75
–60
–45
–30
–15
0
0.5
1.0
1.5
2.0
OUTPUT VOLTAGE (V)
2.5
3.0
1324 G02
0
1.0
2.0 2.5 3.0 3.5 4.0 4.5
DRIVER OUTPUT HIGH VOLTAGE (V)
1.5
5.0
1324 G03
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LTC1324
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TYPICAL PERFORMANCE CHARACTERISTICS
Receiver Output High Voltage
vs Output Current
Receiver Output Low Voltage
vs Output Current
30
–16
110
TA = 25°C
20
15
10
5
100
–12
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
TA = 25°C
–14
25
0
–10
–8
–6
–4
0
0.4
0.8
1.2
1.6
OUTPUT VOLTAGE (V)
0
2.0
2.0
18
875
17
850
2.5
3.0
3.5
4.0
OUTPUT VOLTAGE (V)
4.5
13
12
5 25 45 65 85 105 125
TEMPERATURE (°C)
Driver Skew vs Temperature
3.8
825
800
775
3.6
3.4
750
3.2
700
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
3.0
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
1324 G08
Receiver Output Low Voltage
vs Temperature
1324 G09
Receiver Output High Voltage
vs Temperature
0.8
4.00
I = 8mA
I = 8mA
0.7
3.75
0.6
3.50
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
1324 G06
4.0
1324 G07
0.5
0.4
0.3
0.2
0.1
0
–55 –35 –15
3.25
3.00
2.75
2.50
2.25
5 25 45 65 85 105 125
TEMPERATURE (°C)
1324 G10
4
5 25 45 65 85 105 125
TEMPERATURE (°C)
4.2
725
11
10
–55 –35 –15
60
40
–55 –35 –15
5.0
TIME (ns)
SUPPLY CURRENT (µA)
900
14
70
Supply Current (Driver and
Receiver Enabled) vs Temperature
19
15
80
1324 G05
Receiver Short-Circuit Current
vs Temperature
16
90
50
–2
1324 G04
OUTPUT CURRENT (mA)
Driver Short-Circuit Current
vs Temperature
2.00
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
1324 G11
LTC1324
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TYPICAL PERFORMANCE CHARACTERISTICS
Receiver t PLH – t PHL
vs Temperature
Driver Differential Output Voltage
vs Temperature
3.1
8
RL = 100Ω
7
2.9
6
2.8
5
TIME (ns)
DIFFERENTIAL VOLTAGE (V)
3.0
2.7
2.6
4
3
2.5
2
2.4
1
2.3
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
0
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
1324 G12
1324 G13
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PIN FUNCTIONS
NC (Pins 1, 13): No Internal Connection.
GND (Pin 8): Ground.
SR (Pin 2): Slew Rate Control (TTL Compatible). A high
level on this pin forces the RS485 driver into the low slew
rate mode. A low level forces the driver into the high slew
rate or normal mode. Connected to an internal pull-down.
RXD + (Pin 9): RS485 Receiver Noninverting Input. When
this pin is ≥ 200mV above RXD –, RXDO will be high. When
this pin is ≥ 200mV below RXD –, RXDO will be low.
TXD (Pin 3): RS485 Driver Input (TTL Compatible).
TXD + (Pin 11): RS485 Driver Noninverting Output.
TXDEN (Pin 4): Driver Output Enable (TTL Compatible). A
high level on this pin and a low level on TXDEN (Pin 15)
forces the RS485 driver into three-state. A low level
enables the driver.
TXD – (Pin 12): RS485 Driver Inverting Output.
SHDN (Pin 5): Shutdown Input (TTL Compatible). When
this pin is high, the chip is shut down; the driver and
receiver outputs three-state; and the supply current drops
to 1µA. A low level on this pin allows normal operation.
RXEN (Pin 6): Receiver Enable (TTL Compatible). A high
level on this pin and a low level on RXEN (Pin 14) disables
the receiver and three-states the logic outputs. A low level
allows normal operation.
RXDO (Pin 7): RS485 Receiver Output.
RXD – (Pin 10): RS485 Receiver Inverting Input.
RXEN (Pin 14): Receiver Enable (TTL Compatible). A low
level on this pin and a high level on RXEN (Pin 6) disables
the receiver and three-states the logic outputs. A high level
allows normal operation. Connected to an internal pulldown.
TXDEN (Pin 15): Driver Output Enable (TTL Compatible).
A low level on this pin and a high level on TXDEN (Pin 4)
forces the RS485 driver into three-state. A high level
enables the driver. Connected to an internal pull-down.
VCC (Pin 16): The Positive Supply Input. 4.75V ≤ VCC ≤
5.25V. Requires a 1µF bypass capacitor to ground.
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LTC1324
TEST CIRCUITS
VCC
TXD +
RL
CL
TXD +
TXI
VOD
TXD –
RL
RXD +
RL
CL
S1
RXDO
500Ω
RXD –
OUTPUT
15pF
VOC
CL
TXD –
1324 F02
1324 F01
1324 F03
Figure 1
Figure 2
Figure 3
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SWITCHING WAVEFORMS
3V
1.5V
TXD
f = 1MHz: t r ≤ 10ns: t f ≤ 10ns
1.5V
0V
t PLH
tPHL
VO
VDIFF = V(TXD+) – V(TXD –)
90%
50%
10%
–VO
90%
50%
10%
1/2 VO
tr
tf
TXD –
VO
TXD +
tSKEW
tSKEW
1324 F04
Figure 4. Differential Driver
3V
1.5V
TXDEN
0V
f = 1MHz: t r ≤ 10ns: t f ≤ 10ns
t ZL
1.5V
t LZ
5V
TXD +, TXD –
2.3V
OUTPUT NORMALLY LOW
VOL
t ZH
OUTPUT NORMALLY HIGH
VOH
0.5V
t HZ
0.5V
TXD –, TXD +
2.3V
0V
1324 F05
Figure 5. Differential Driver Enable and Disable
V OD2
(RXD +) – (RXD –)
0V
f = 1MHz: tr ≤ 10ns: tf ≤ 10ns
0V
–V OD2
tPLH
tPHL
VOH
RXDO
1.5V
VOL
1.5V
1324 F06
Figure 6. Differential Receiver
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S2
LTC1324
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SWITCHING WAVEFORMS
3V
1.5V
RXEN
1.5V
f = 1MHz: tr ≤ 10ns: tf ≤ 10ns
0V
tZL
t LZ
5V
RXO, RXO, RXDO
2.3V
OUTPUT NORMALLY LOW
VOL
tZH
OUTPUT NORMALLY HIGH
VOH
0.5V
t HZ
0.5V
2.3V
RXO, RXO, RXDO
0V
1324 F07
Figure 7. Receiver Enable and Disable
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APPLICATIONS INFORMATION
Thermal Shutdown Protection
The LTC1324 includes a thermal shutdown circuit which
protects against prolonged shorts at the driver outputs. If
a driver output is shorted to another output, ground or to
the power supply, the current will be initially limited to a
maximum of 250mA. When the die temperature rises
above 150°C, the thermal shutdown circuit turns off the
driver outputs. When the die cools to about 130°C, the
outputs turn on. If the short still exists, the part will heat
again and the cycle will repeat. This oscillation occurs at
about 10Hz and prevents the part from being damaged by
excessive power dissipation. When the short is removed,
the part will return to normal operation.
capacitor T network between each driver, receiver and the
connector. Unfortunately, the resistors will attenuate the
driver’s output signal applied to the cable. Because the
LTC1324 uses a single 5V supply, the resistors’ values
should be reduced to 5.1Ω to ensure enough voltage
swing on the cable (Figure 8). Another way to get maximum swing and EMI immunity is to use a ferrite bead and
capacitor as the T network (Figure 9). For data rates below
250kbps, the LTC1324 features a low EMI mode which
limits the rise time of the drivers to 400ns. With a lower
rise time, the EMI network can be eliminated, allowing
more signal voltage to reach the cable. Figures 10 and 11
show the output signals of the driver with different slew
rates.
Power Shutdown
5.1Ω
5.1Ω
The power shutdown feature of the LTC1324 is designed
for battery-powered systems. When SHDN is forced high,
the part enters shutdown mode. In shutdown, the supply
current typically drops from 1mA to 1µA and the driver and
receiver outputs are three-stated.
TXD +
100pF
TXD
120Ω
TXD –
5.1Ω
5.1Ω
100pF
1324 F08
Figure 8
Supply Bypassing
The LTC1324 requires VCC be bypassed to prevent data
errors. A 1µF capacitor from VCC to ground is adequate.
FERRITE BEAD
FERRITE BEAD
100pF
EMI Filters and Slew Rate Control
1324 F09
Most LocalTalk applications need to use an electromagnetic interference (EMI) filter consisting of a resistor-
Figure 9
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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LTC1324
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APPLICATIONS INFORMATION
1324 F10
1324 F11
Figure 10. High Slew Rate Mode
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PACKAGE DESCRIPTION
Figure 11. Low Slew Rate Mode
Dimensions in inches (millimeters) unless otherwise noted.
N Package
16-Lead PDIP (Narrow 0.300)
(LTC DWG # 05-08-1510)
0.130 ± 0.005
(3.302 ± 0.127)
0.300 – 0.325
(7.620 – 8.255)
0.009 – 0.015
(0.229 – 0.381)
(
+0.635
8.255
–0.381
0.045 – 0.065
(1.143 – 1.651)
0.015
(0.381)
MIN
+0.025
0.325 –0.015
)
0.770*
(19.558)
MAX
0.065
(1.651)
TYP
0.045 ± 0.015
(1.143 ± 0.381)
0.125
(3.175)
MIN
16
15
14
13
12
11
10
1
2
3
4
5
6
7
0.255 ± 0.015*
(6.477 ± 0.381)
0.018 ± 0.003
(0.457 ± 0.076)
0.100 ± 0.010
(2.540 ± 0.254)
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N16 0694
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTURSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm).
SW Package
16-Lead Plastic Small Outline (Wide 0.300)
(LTC DWG # 05-08-1620)
0.005
(0.127)
RAD MIN
0.291 – 0.299
(7.391 – 7.595)
(NOTE 2)
0.010 – 0.029 × 45°
(0.254 – 0.737)
0.093 – 0.104
(2.362 – 2.642)
NOTE 1
16
15
14
13
12
11 10
9
0.037 – 0.045
(0.940 – 1.143)
0.394 – 0.419
(10.007 – 10.643)
NOTE 1
0° – 8° TYP
0.009 – 0.013
(0.229 – 0.330)
0.398 – 0.413
(10.109 – 10.490)
(NOTE 2)
0.050
(1.270)
TYP
0.004 – 0.012
(0.102 – 0.305)
0.014 – 0.019
(0.356 – 0.482)
TYP
0.016 – 0.050
(0.406 – 1.270)
NOTE:
1. PIN 1 IDENT, NOTCH ON TOP AND CAVITIES ON THE BOTTOM OF PACKAGES ARE THE MANUFACTURING OPTIONS.
THE PART MAY BE SUPPLIED WITH OR WITHOUT ANY OF THE OPTIONS.
2. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006 INCH (0.15mm).
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2
3
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SOL16 0392
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Linear Technology Corporation
LT/GP 0596 7K • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● TELEX: 499-3977
 LINEAR TECHNOLOGY CORPORATION 1995