LINER LTC1323CSW Single 5v appletalk transceiver Datasheet

LTC1323
Single 5V
AppleTalk Transceiver
®
U
DESCRIPTIO
FEATURES
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The LTC®1323 is a multi-protocol line transceiver designed
to operate on AppleTalk or EIA562-compatible singleended networks while operating from a single 5V supply.
There are two versions of the LTC1323 available: a 16-pin
version designed to connect to an AppleTalk network,
and a 24-pin version which also includes the additional
single-ended drivers and receivers necessary to create
an Apple-compatible serial port. An on-board charge
pump generates a – 5V supply which can be used to
power external devices. Additionally, the 24-pin LTC1323
features a micropower keep-alive mode during which
one of the single-ended receivers is kept active to monitor
external wake-up signals. The LTC1323 draws only 2.4mA
quiescent current when active, 65µA in receiver keepalive mode, and 0.5µA in shutdown, making it ideal for
use in battery-powered systems.
Single Chip Provides Complete
LocalTalk®/AppleTalk Port
Operates From a Single 5V Supply
ESD Protection to ±10kV on Receiver Inputs
and Driver Outputs
Low Power: ICC = 2.4mA Typ
Shutdown Pin Reduces ICC to 0.5µA Typ
Receiver Keep-Alive Function: ICC = 65µA Typ
Differential Driver Drives Either Differential
AppleTalk or Single-Ended EIA562 Loads
Drivers Maintain High Impedance in Three-State or
with Power Off
Thermal Shutdown Protection
Drivers are Short-Circuit Protected
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APPLICATI
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■
S
The differential driver can drive either differential AppleTalk
loads or conventional single-ended loads. The driver
outputs three-state when disabled, during shutdown, in
receiver keep-alive mode, 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/Palmtop Computers
Battery-Powered Systems
, LTC and LT are registered trademarks of Linear Technology Corporation.
AppleTalk and LocalTalk are registered trademarks of Apple Computer, Inc.
UO
TYPICAL APPLICATI
LTC1323
0.33µF
2
CHARGE PUMP
CPEN 3
TXD 4
5V
24
1
21
DX
TXI 5
20 TXD –
TXDEN 6
19 TXD +
SHDN 7
18 TXO
RXEN 8
17 RXI
RXO 9
RXO 10
RX
RX
12
16 RXI
15 RXD –
14 RXD +
RXDO 11
RX
1µF
23
22
DX
+
5Ω TO 10Ω
5Ω TO 10Ω
EMI FILTER =
0.33µF
1µF
100pF
+
EMI FILTER
EMI FILTER
EMI FILTER
EMI FILTER
8
7
6
EMI FILTER
5
4
3
EMI FILTER
2
1
EMI FILTER
13
LTC1323 • TA01
1
LTC1323
W W
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AXI U
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ABSOLUTE
RATI GS
Supply Voltage (VCC) ................................................ 7V
Input Voltage
Logic Inputs .............................. – 0.3V to VCC + 0.3V
Receiver Inputs ................................................ ±15V
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
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PACKAGE/ORDER I FOR ATIO
TOP VIEW
C1+
1
28 VCC
C2 – 2
27 C2+
CPEN 3
26 C2 –
TXD 4
25 NC
TXI 5
24 NC
TXDEN 6
23 VEE
ORDER PART
NUMBER
LTC1323CG
22 TXD–
SHDN 7
21 TXD+
RXEN 8
RXO 9
20 TXO
RXO 10
19 RXI
RXDO 11
18 RXI
NC 12
17 RXD–
NC 13
RXD+
16
GND 14
1
24 VCC
23 C2+
CPEN 3
22 C2 –
TXD 4
21 VEE
TXI 5
20 TXD –
TXDEN 6
19 TXD+
SHDN 7
18 TXO
RXEN 8
17 RXI
RXO 9
16 RXI
RXO 10
15 RXD –
RXDO 11
14 RXD+
GND 12
13 PGND
SW PACKAGE
24-LEAD PLASTIC SO WIDE
TJMAX = 125°C, θJA = 85°C/W
Consult factory for Industrial and Military grade parts.
2
16 VCC
C1– 2
15 C2+
TXD 3
14 C2 –
TXDEN 4
13 VEE
SHDN 5
12 TXD –
RXEN 6
11 TXD +
RXDO 7
10 RXD –
9
TJMAX = 125°C, θJA = 85°C/W
TJMAX = 150°C, θJA = 96°C/W
C1 – 2
LTC1323CS
1
S PACKAGE
16-LEAD PLASTIC SO
15 PGND
TOP VIEW
TOP VIEW
C1+
GND 8
G PACKAGE
28-LEAD PLASTIC SSOP
C1+
ORDER PART
NUMBER
ORDER PART
NUMBER
LTC1323CSW
RXD+
LTC1323
ELECTRICAL CHARACTERISTICS
SYMBOL
VCC = 5V ±10%, TA = 0°C to 70°C (Notes 2, 3)
PARAMETER
CONDITIONS
Normal Operation Supply Current
No Load, SHDN = 0V, CPEN = 0V, TXDEN = 0V,
RXEN = 0V
Receiver Keep-Alive Supply Current
MIN
TYP
MAX
UNITS
●
2.4
4
mA
No Load, SHDN = 0V, CPEN = VCC, TXDEN = 0V,
RXEN = 0V
●
65
100
µA
Shutdown Supply Current
No Load, SHDN = VCC, CPEN = X, TXDEN = X,
RXEN = 0V
●
0.5
10
µA
VEE
Negative Supply Output Voltage
ILOAD ≤ 10mA (Note 4),
VCC = 5V, RL = 100Ω (Figure 1),
TXI = VCC, RTXO = 3k (Figure 5)
●
–5
– 4.5
V
fOSC
Charge Pump Oscillator Frequency
Supplies
ICC
– 5.5
200
kHz
Differential Driver
VOD
Differential Output Voltage
No Load
RL = 100Ω (Figure 1)
∆VOD
Change in Magnitude of Differential
Output Voltage
RL = 100Ω (Figure 1)
●
●
±8
±2
V
0.2
V
3
V
Differential Driver
VOC
Differential Common-Mode
Output Voltage
RL = 100Ω
VOS
Single-Ended Output Voltage
No Load
RL = 3k to GND
●
●
VCMR
Common-Mode Range
SHDN = VCC or CPEN = VCC or Power Off
●
ISS
Short-Circuit Current
– 5V ≤ VO ≤ 5V
●
IOZ
Three-State Output Current
SHDN = VCC or CPEN = VCC or Power Off,
– 10V ≤ VO ≤ 10V
●
±4.0
±3.7
35
V
V
±10
V
120
500
mA
±2
±200
µA
Single-Ended Driver (Note 5)
±4.5
±3.7
VOS
Single-Ended Output Voltage
No Load
RL = 3k to GND
●
●
VCMR
Common-Mode Range
SHDN = VCC or CPEN = VCC or TXDEN = VCC
or Power Off
●
ISS
Short-Circuit Current
– 5V ≤ VO ≤ 5V
●
IOZ
Three-State Output Current
SHDN = VCC or CPEN = VCC or TXDEN = VCC
or Power Off, – 10V ≤ VO ≤ 10V
●
Input Resistance
– 7V ≤ VIN ≤ 7V
●
12
Differential Receiver Threshold Voltage
– 7V ≤ VCM ≤ 7V
●
– 200
Differential Receiver Input Hysteresis
– 7V ≤ VCM ≤ 7V
●
Single-Ended Input, Low Voltage
(Note 5)
●
Single-Ended Input, High Voltage
(Note 5)
●
2
V
VOH
Output High Voltage
IO = – 4mA
●
3.5
V
VOL
Output Low Voltage
IO = 4mA
●
ISS
Output Short-Circuit Current
– 5V ≤ VO ≤ 5V
●
IOZ
Output Three-State Current
– 5V ≤ VO ≤ 5V, RXEN = VCC
●
35
V
V
±10
V
220
500
mA
±2
±200
µA
200
mV
Receivers
RIN
kΩ
70
mV
0.8
7
±2
V
0.4
V
85
mA
±100
µA
3
LTC1323
ELECTRICAL CHARACTERISTICS
SYMBOL
VCC = 5V ±10%, TA = 0°C to 70°C (Notes 2 and 3)
PARAMETER
CONDITIONS
MIN
VIH
Input High Voltage
All Logic Input Pins
●
VIL
Input Low Voltage
All Logic Input Pins
●
IC
Input Current
All Logic Input Pins
●
Differential Driver Propagation Delay
RL = 100Ω, CL = 100pF (Figures 2, 7)
Differential Driver Propagation Delay
with Single-Ended Load
RL = 3k, CL = 100pF (Figures 3, 9)
Single-Ended Driver Propagation Delay
Differential Receiver Propagation Delay
Single-Ended Receiver
Propagation Delay
TYP
MAX
UNITS
Logic Inputs
2.0
V
0.8
V
±1.0
±20
µA
●
40
120
ns
●
120
180
ns
RL = 3k, CL = 100pF, (Figures 5, 10) (Note 5)
●
40
120
ns
CL = 15pF (Figures 2, 11)
●
70
160
ns
CL = 15pF (Figures 6, 12) (Note 5)
●
70
160
ns
Inverting Receiver Propagation Delay
in Keep-Alive Mode,
SHDN = 0V, CPEN = VCC
CL = 15pF (Figures 6, 12) (Note 5)
●
150
600
ns
tSKEW
Differential Driver Output to Output
RL = 100Ω, CL = 100pF (Figures 2, 7)
●
10
50
ns
tr, tf
Differential Driver Rise/Fall Time
RL = 100Ω, CL = 100pF (Figures 2, 7)
●
50
150
ns
Differential Driver Rise/Fall Time
with Single-Ended Load
RL = 3k, CL = 100pF (Figures 3, 9)
●
50
150
ns
Single-Ended Driver Rise/Fall Time
RL = 3k, CL = 100pF (Figures 5, 10) (Note 5)
●
15
80
ns
Differential Driver Output Active
to Disable
CL = 15pF (Figures 4, 8)
●
180
250
ns
Any Receiver Output Active to Disable
CL = 15pF (Figures 4, 13)
●
30
100
ns
Differential Driver
Enable to Output Active
CL = 15pF (Figures 4, 8)
●
180
250
ns
Any Receiver, Enable to Output Active
CL = 15pF (Figures 4, 13)
●
30
100
Supply Rise Time from Shutdown
or Receiver Keep-Alive
C1 = C2 = 0.33µF, CVEE = 1µF
●
0.2
Switching Characteristics
tPLH, tPHL
tHDIS, tLDIS
tENH, tENL
VEER
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; all currents out of device
pins are negative. All voltages are referenced to ground unless otherwise
specified.
4
Note 3: All typicals are given at VCC = 5V, TA = 25°C.
Note 4: ILOAD is an external current being sunk into the VEE pin.
Note 5: These specifications apply to the 24-pin SO Wide package only.
ns
ms
LTC1323
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TYPICAL PERFORMANCE CHARACTERISTICS
Charge Pump Output Voltage
vs Load Current
–2.5
–3.0
–3.5
– 4.0
– 4.5
– 5.0
–5.5
– 6.0
5
5
4
4
3
2
1
0
–1
–2
–3
TA = 25°C
VS = 5V
–4
–5
0
5
10
20
15
LOAD CURRENT (mA)
25
50 100 200 300 500 1k 2k 3k
LOAD RESISTANCE (Ω)
30
LTC1323 • TPC01
2.75
2.50
2.25
2.00
1.75
50
75
25
TEMPERATURE (˚C)
100
0
–1
–2
–3
–4
–5
50 100 200 300 500 1k 2k 3k
LOAD RESISTANCE (Ω)
125
LTC1323 • TPC04
4.5
5k 10k
LTC1323 • TPC03
Single-Ended Driver Swing
vs Temperature
5
VS = 5V
RL = 100Ω
SINGLE-ENDED DRIVER OUTPUT (V)
DIFFERENTIAL DRIVER OUTPUT (V)
SUPPLY CURRENT (mA)
3.00
0
1
5k 10k
5.0
VS = 5V
NO LOAD
TA = 25°C
VS = 5V
2
Differential Driver Swing
vs Temperature
3.50
1.50
–50 –25
3
LTC1323 • TPC02
Supply Current vs Temperature
3.25
SINGLE-ENDED DRIVER OUTPUT (V)
TA = 25°C
VS = 5V
RL(DIFF) = 100Ω
RL(SE) = 3k TO GND
VTXI = 5V
DIFFERENTIAL DRIVER OUTPUT (V)
CHARGE PUMP OUTPUT VOLTAGE (V)
–2.0
Single-Ended Driver Swing
vs Load Resistance
Differential Driver Swing
vs Load Resistance
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
–50 –25
50
25
0
75
TEMPERATURE (°C)
100
125
LTC1323 • TPC05
4
3
VS = 5V
RL = 3k TO GND
2
1
0
–1
–2
–3
–4
–5
–50 –25
50
25
0
75
TEMPERATURE (°C)
100
125
LTC1323 • TPC06
5
LTC1323
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PI FU CTIO S
LTC1323CS
C1+ 1
LTC1323CSW
16 VCC
C1+ 1
2
15 C2 +
C1–
TXD 3
14 C2 –
TXDEN 4
13 VEE
C1–
SHDN 5
CHARGE PUMP
DX
RXEN 6
RXDO 7
GND 8
RX
CHARGE PUMP
2
TXD 4
12 TXD
11 TXD
+
TXDEN 6
–
SHDN 7
9 RXD+
RXEN 8
10 RXD
C1+ 1
24 VCC
23
C2 +
C1–
22 C2 –
CPEN 3
–
LTC1323CG
21 VEE
DX
19
DX
28 VCC
2
27 C2 +
CPEN 3
26 C2 –
TXD 4
–
TXI 5
TXD +
TXDEN 6
20 TXD
TXI 5
CHARGE PUMP
25 NC
DX
24 NC
23 VEE
DX
18 TXO
SHDN 7
22 TXD –
17 RXI
RXEN 8
21 TXD +
RXO 9
20 TXO
RX
16 RXI
RXO 9
RX0 10
RX
RXDO 11
15 RXD
–
RX0 10
14 RXD
+
RXDO 11
13 PGND
NC 12
RX
18 RXI
RX
GND 12
19 RXI
RX
17 RXD –
16 RXD +
NC 13
RX
GND 14
C1+ : C1 Positive Input. Connect a 0.33µF capacitor between C1+ and C1–.
C1–: C1 Negative Input. Connect a 0.33µF capacitor between C1+ and C1–.
CPEN: TTL Level Charge Pump Enable Input. With CPEN
held low, the charge pump is enabled and the chip operates normally. When CPEN is pulled high, the charge
pump is disabled as well as both drivers, the noninverting
single-ended receiver, and the differential receiver. The
inverting single-ended receiver (RXI) is kept alive to
monitor the control line and ICC drops to 65µA. To turn
off the receiver and drop ICC to 0.5µA, pull the SHDN pin
high.
TXD: Differential Driver Input (TTL compatible).
TXI: Single-Ended Driver Input (TTL compatible).
TXDEN: Differential Driver Output Enable (TTL compatible). A high level on this pin forces the differential driver
into three-state; a low level enables the driver. This input
does not affect the single-ended driver.
SHDN: Shutdown Input (TTL compatible). When this pin
is high, the chip is shut down. All driver and receiver
outputs are three-state, the charge pump turns off, and the
supply current drops to 0.5µA. A low level on this pin
allows normal operation.
6
15 PGND
RXEN: Receiver Enable (TTL compatible). A high level
on this pin disables the receivers and three-states the
logic outputs; a low level allows normal operation.
RXO: Inverting Single-Ended Receiver Output. Remains
active in the receiver keep-alive mode.
RXO: Noninverting Single-Ended Receiver Output.
RXDO: Differential Receiver Output.
GND: Signal Ground. Connect to PGND with 24-pin
package.
PGND: Power ground is connected internally to the charge
pump and differential driver. Connect to the GND pin.
RXD+: Differential 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.
RXD–: Differential Receiver Inverting Input.
RXI: Noninverting Receiver Input. This input controls the
RXO output.
RXI: Inverting Receiver Input. This input controls the RXO
output. In receiver keep-alive mode (CPEN high, SHDN
low), this receiver can be used to monitor a wake-up
control signal.
LTC1323
U
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PI FU CTIO S
C2 –: C2 Negative Input. Connect a 0.33µF capacitor
between C2+ and C2 –.
TXO: Single-Ended Driver Output.
TXD+: Differential Driver Noninverting Output.
TXD–: Differential Driver Inverting Output.
C2+: C2 Positive Input. Connect a 0.33µF capacitor
between C2+ and C2–.
VEE: Negative Supply Charge Pump Output. Requires a
1µF bypass capacitor to ground. If an external load is
connected to the VEE pin, the bypass capacitor value
should be increased to 4.7µF.
VCC: Positive Supply Input. 4.5V ≤ VCC ≤ 5.5V. Requires a
1µF bypass capacitor to ground.
TEST CIRCUITS
TXD +
R
VOD
TXI
R
CL
RXD+
RL
TXD –
VOC
CL
RXD+
RXDO
RXD –
TXI
TXD +
RL
TXD –
15pF
RL
CL
CL
TXD –
LTC1323 • F03
LTC1323 • F01
LTC1323 • F02
Figure 1
Figure 2
Figure 3
VCC
S1
TXI
500Ω
TXO
RXI
RXO
RXI
RXO
OUTPUT
RL
CL
CL
CL
CL
S2
LTC1323 • F04
LTC1323 • F05
Figure 4
LTC1323 • F06
Figure 5
Figure 6
U
W
SWITCHI G WAVEFOR S
3V
1.5V
TXD
f = 1MHz: tr ≤ 10ns: tf ≤ 10ns
1.5V
0V
tPLH
tPHL
VO
90%
50%
10%
–VO
VDIFF = V(TXD +) – V(TXD – )
1/2 VO
tr
90%
50%
10%
tf
TXD –
VO
TXD +
tSKEW
tSKEW
LTC1323 • F07
Figure 7. Differential Driver
7
LTC1323
U
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SWITCHI G WAVEFOR S
3V
1.5V
TXDEN
0V
f = 1MHz: tr ≤ 10ns: tf ≤ 10ns
tZL
tLZ
5V
TXD+, TXD –
2.3V
OUTPUT NORMALLY LOW
VOL
tZH
OUTPUT NORMALLY HIGH
VOH
–
TXD , TXD
1.5V
0.5V
tHZ
0.5V
+
2.3V
0V
LTC1323 • F08
Figure 8. Differential Driver Enable and Disable
3V
1.5V
TXD
f = 1MHz: tr ≤ 10ns: tf ≤ 10ns
1.5V
0V
tPHL
tPLH
VOH
TXD –
0V
0V
VOL
VOH
TXD +
VOL
90%
90%
0V
10%
0V
10%
tr
tf
LTC1323 • F09
Figure 9. Differential Driver With Single-Ended Load
3V
1.5V
TXI
f = 1MHz: tr ≤ 10ns: tf ≤ 10ns
1.5V
0V
tPHL
VOH
TXO
tPLH
90%
90%
0V
10%
VOL
0V
10%
tr
LTC1323 • F10
tr
Figure 10. Single-Ended Driver
V OD2
+
–
0V
(RXD ) – (RXD )
f = 1MHz: tr ≤ 10ns: tf ≤ 10ns
0V
–VOD2
tPLH
tPHL
VOH
RXDO
VOL
1.5V
1.5V
LTC1323 • F11
Figure 11. Differential Receiver
8
LTC1323
U
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SWITCHI G WAVEFOR S
VIH
f = 1MHz: tr ≤ 10ns: tf ≤ 10ns
1.5V
RXI, RXI
1.5V
VIL
tPHL
tPLH
VOH
2.4V
RXI
0.8V
VOL
VIH
1.5V
RXI
1.5V
V
LTC1323 • F12
Figure 12. Single-Ended Receiver
3V
1.5V
RXEN
f = 1MHz: tr ≤ 10ns: tf ≤ 10ns
0V
tZL
1.5V
tLZ
5V
RXO, RXO, RXDO
2.3V
OUTPUT NORMALLY LOW
VOL
tZH
OUTPUT NORMALLY HIGH
VOH
0.5V
tHZ
0.5V
2.3V
RXO, RXO, RXDO
0V
LTC1323 • F13
Figure 13. Receiver Enable and Disable
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APPLICATIO S I FOR ATIO
Functional Description
The “serial port” on the back of an Apple-compatible
computer or peripheral is a fairly versatile “multi-protocol”
connector. It must be able to connect to a wide bandwidth
LAN (an AppleTalk/LocalTalk network), which requires a
high speed differential transceiver to meet the AppleTalk
specification, and it must also be able to connect directly to
a printer or modem through a short RS232 style link. The
LTC1323 is designed to provide all the functions necessary
to implement such a port on a single chip. Two versions of
the LTC1323 are available: a 16-pin SO version which
provides the minimum solution for interfacing to an
AppleTalk network in a smaller package, and a larger 24-pin
SO Wide version which additionally includes all the handshaking lines required to implement a complete AppleTalk/
modem/printer serial port. All LTC1323s run from a single
5V power supply while providing true single-ended compatibility, and include a 0.5µA low power shutdown mode
to improve lifetime in battery-powered devices. The 24pin SO Wide version also includes a receiver keep-alive
mode for monitoring external signals while drawing 65µA
typically.
The LTC1323 includes an RS422-compatible differential
driver/receiver pair for data transmission, with the driver
specified to drive 2V into the 100Ω primary of a typical
LocalTalk interface transformer/RFI interference network.
Either output of the differential RS422 driver can also act as
an single-ended driver, allowing the LTC1323 to communicate over a standard serial connection. The 24-pin SO
Wide LTC1323 also includes an extra single ended only
driver and two extra RS232-compatible single-ended receivers for handshaking lines. All versions include an onboard charge pump to provide a regulated – 5V supply
required for the single-ended drivers. The charge pump
can also provide up to 10mA of external load current to
power other circuitry.
9
LTC1323
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APPLICATIO S I FOR ATIO
Driving Differential AppleTalk or Single-Ended Loads
Power Shutdown
The differential driver is able to drive either an AppleTalk
load or a single-ended load such as a printer or modem.
With a differential AppleTalk load, TXD+ and TXD – will
typically swing between 1.2V and 3.5V (Figure 14a). With
a single-ended 3k load such as a printer, either TXD+ or
TXD – will meet the single-ended voltage swing requirement of ±3.7V (Figure 14b). An automatic switching circuit
prevents the differential driver from overloading the charge
pump if the outputs are shorted to ground while driving
single-ended signals. This allows the second single-ended
driver to continue to operate normally when the first is
shorted, and allows external circuitry attached to the charge
pump output to continue to operate even if there are faults
at the driver outputs.
The power shutdown feature of the LTC1323 is designed
for battery-powered systems. When SHDN is forced
high the part enters shutdown mode. In shutdown the
supply current typically drops from 2.4mA to 0.5µA , the
charge pump turns off, and the driver and receiver
outputs are three-stated.
VCC = 5V
+
24
1µF
EXTERNAL
CHIP
GND
VEE
LTC1323
13
21
+
C1
VCC
12
–5.5V ≤ VEE ≤ –4.5V
IVEE ≤ 10mA
LTC1323 • F15
Figure 14
Thermal Shutdown Protection
The LTC1323 includes a thermal shutdown circuit which
protects against prolonged shorts at the driver outputs. If
a driver output is shorted to another output or to the power
supply, the current will be initially limited to a maximum of
500mA. When the die temperature rises above 150°C, the
thermal shutdown circuit disables the driver outputs.
When the die cools to about 130°C, the outputs are reenabled. 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.
10
The 24-pin SO Wide version of the LTC1323 also features
a power saving receiver keep-alive mode. When CPEN is
pulled high the charge pump is turned off and the outputs
of both drivers, the noninverting single-ended receiver and
the differential receiver are forced into three-state. The
inverting single-ended receiver (RXI) is kept alive with ICC
dropping to 65µA and the receiver delay time increasing to
a maximum of 400ns. The receiver can then be used to
monitor a wake-up control signal.
Charge Pump Capacitors and Supply Bypassing
IVEE
4.7µF
Receiver Keep-Alive Mode (24-Pin SO Wide Only)
The LTC1323 requires two external 0.33µF capacitors for
the charge pump to operate: one from C1+ to C1– and one
from C2 + to C2 –. These capacitors should be low ESR
types and should be mounted as close as possible to the
LTC1323. Monolithic ceramic capacitors work well in this
application. Do not use capacitors greater than 2µF at the
charge pump pins or internal peak currents can rise to
destructive levels. The LTC1323 also requires that both VCC
and VEE be well bypassed to ensure proper charge pump
operation and prevent data errors. A 1µF capacitor from
VCC to ground is adequate. A 1µF capacitor is required from
VEE to ground and should be increased to 4.7µF if an
external load is connected to the VEE pin. Ceramic or
tantalum capacitors are adequate for power supply bypassing; aluminum electrolytic capacitors should only be
used if their ESR is low enough for proper charge pump
operation. Inadequate bypass or charge pump capacitors
will cause the charge pump output to go out of regulation
prematurely, degrading the output swing at the SINGLEENDED driver outputs.
LTC1323
U U
W
U
APPLICATIO S I FOR ATIO
Driving an External Load from VEE
the LTC1323 uses a single supply differential driver, the
resistor values should be reduced to 5Ω to 10Ω to guarantee adequate voltage swing on the cable (Figure 16a). In
most applications, removing the resistors completely does
not cause an increase in EMI as long as a shielded connector and cable are used (Figure 16b). With the resistors
removed the only DC load is the primary resistance of the
LocalTalk transformer. This will increase the DC standby
current when the driver outputs are active, but does not
adversely affect the drivers because they can handle a
direct indefinite short circuits without damage. Transformer primary resistance should be above 15Ω to keep the
LTC1323 operating normally and prevent it from entering
thermal shutdown. For maximum swing and EMI immunity, a ferrite bead and capacitor T network can be used
(Figure 16c).
An external load may be connected between ground and
the VEE pin as shown in Figure 15. The LTC1323 VEE pin
will sink up to a maximum of 10mA while maintaining the
pin voltage between – 4.5V and – 5.5V. If an external load
is connected, the VEE bypass capacitor should be increased to 4.7µF. Both LTC1323 and the external chip
should have separate VCC bypass capacitors but can
share the VEE capacitor.
EMI Filter
Most LocalTalk applications use an electromagnetic interference (EMI) filter consisting of a resistor-capacitor T
network between each driver and receiver and the connector. Unfortunately, the resistors significantly attenuate the
drivers output signals before they reach the cable. Because
5Ω TO 10Ω
VCC = 5V
FERRITE BEAD
5Ω TO 10Ω
100pF
+
24
1µF
13
21
+
(a)
EXTERNAL
CHIP
GND
VEE
LTC1323
100pF
100pF
C1
VCC
12
FERRITE BEAD
(b)
(c)
LTC1323 • F16
Figure 16. EMI Filters
IVEE
4.7µF
–5.5V ≤ VEE ≤ –4.5V
IVEE ≤ 10mA
LTC1323 • F15
Figure 15
U
TYPICAL APPLICATIONS N
Typical LocalTalk Connection
5V
+
1µF
16
1
0.33µF
2
15
CHARGE PUMP
14
13
0.33µF
1µF
DATA IN
TX ENABLE
SHDN
RX ENABLE
DATA OUT
3
12
TX
LocalTalk
TRANSFORMER
11
4
5
6
7
100pF
+
LTC1323CS
120Ω
100pF
10
RX
8
100pF
9
LTC1323 • TA02
100pF
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.
11
LTC1323
U
PACKAGE DESCRIPTION
Dimensions in inches (millimeters) unless otherwise noted.
G Package
28-Lead Plastic SSOP (0.209)
(LTC DWG # 05-08-1640)
0.205 – 0.212**
(5.20 – 5.38)
0.397 – 0.407*
(10.07 – 10.33)
28 27 26 25 24 23 22 21 20 19 18 17 16 15
0.068 – 0.078
(1.73 – 1.99)
0° – 8°
0.005 – 0.009
(0.13 – 0.22)
0.301 – 0.311
(7.65 – 7.90)
0.0256
(0.65)
BSC
0.022 – 0.037
(0.55 – 0.95)
0.002 – 0.008
(0.05 – 0.21)
0.010 – 0.015
*DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH
(0.25 – 0.38)
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSIONS DO NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
1 2 3 4 5 6 7 8 9 10 11 12 13 14
G28 SSOP 0694
S Package
16-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.386 – 0.394*
(9.804 – 10.008)
0.010 – 0.020
× 45°
(0.254 – 0.508)
0.008 – 0.010
(0.203 – 0.254)
16
0.004 – 0.010
(0.101 – 0.254)
0.053 – 0.069
(1.346 – 1.752)
15
13
14
12
11
10
9
0° – 8° TYP
0.016 – 0.050
0.406 – 1.270
0.050
(1.270)
TYP
0.014 – 0.019
(0.355 – 0.483)
0.150 – 0.157**
(3.810 – 3.988)
0.228 – 0.244
(5.791 – 6.197)
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
S16 0695
3
2
1
5
4
7
6
8
SW Package
24-Lead Plastic Small Outline (Wide 0.300)
(LTC DWG # 05-08-1620)
0.598 – 0.614*
(15.190 – 15.600)
0.291 – 0.299**
(7.391 – 7.595)
0.010 – 0.029 × 45°
(0.254 – 0.737)
0.093 – 0.104
(2.362 – 2.642)
0.037 – 0.045
(0.940 – 1.143)
24
23
22
21
20
19
18
17
16
15
14
13
0° – 8° TYP
0.009 – 0.013
(0.229 – 0.330)
NOTE 1
0.050
(1.270)
TYP
0.014 – 0.019
0.016 – 0.050
(0.356 – 0.482)
(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.
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
12
Linear Technology Corporation
0.394 – 0.419
(10.007 – 10.643)
NOTE 1
0.004 – 0.012
(0.102 – 0.305)
1
2
3
4
5
6
7
8
9
10
11
12
S24 (WIDE) 0695
LT/GP 1194 10K • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7487
(408) 432-1900 ● FAX: (408) 434-0507 ● TELEX: 499-3977
 LINEAR TECHNOLOGY CORPORATION 1994