1
D U
ESCRIPTIO
S
FEATURE U A O
PPLICATI
TYPICAL DI
RO
RO
DI
砭石祛斑泥
5V The LTC ®1485 is a low power differential bus/line trans-ceiver designed for multipoint data transmission standard RS485 applications with extended common-mode range (12V to –7V). It also meets the requirements of RS422.The CMOS with Schottky design offers significant power savings over its bipolar counterpart without sacrificing ruggedness against overload or ESD damage.The driver and receiver feature three-state outputs, with the driver outputs maintaining high impedance over the entire common-mode range. Excessive power dissipation caused by bus contention or fault
s is prevented by a thermal shutdown circuit which forces the driver outputs into a high impedance state. I/O pins are protected against multiple ESD strikes of over ±10kV.
The receiver has a fail-safe feature which guarantees a high output state when the inputs are left open.Both AC and DC specifications are guaranteed from –40°C to 85°C and 4.75V to 5.25V supply voltage range.
s Low Power RS485/RS422 Transceiver s
Level Translator
U S
A O
PPLICATI
s ESD Protection over ±10kV s Low Power: I CC = 1.8mA Typ
s
28ns Typical Driver Propagation Delays with 4ns Skew滑步机
s Designed for RS485 or RS422 Applications s Single 5V Supply
s
–7V to 12V Bus Common-Mode Range Permits ±7V Ground Difference Between Devices on the Bus s Thermal Shutdown Protection
s Power-Up/Down Glitch-Free Driver Outputs
s
Driver Maintains High Impedance in Three-State or with the Power Off
s
Combined Impedance of a Driver Output and Receiver Allows up to 32 Transceivers on the Bus s 60mV Typical Input Hysteresis
s
Pin Compatible with the SN75176A, DS75176A, and SN75LBC176
2
A U G W
A W U W A R BSOLUTE
XI TI S W U U PACKAGE/ORDER I FOR ATIO
(Note 1)
Supply Voltage (V CC ).............................................. 12V Control –0.5V to V CC + 0.5V Control –50mA to 50mA Driver –0.5V to V CC + 0.5V Driver –25mA to 25mA Driver Output Voltages ......................................... ±14V Receiver ±14V Receiver Output Voltages .............. –0.5V to V CC + 0.5V Operating Temperature Range
< 0°C to 70°C LTC1485I .......................................... –40°C to 85°C Storage . –65°C to 150°C Lead Temperature (Soldering, 10 sec.)................ 300°C
SYMBOL PARAMETER
CONDITIONS MIN
TYP MAX UNITS
V OD1Differential Driver Output Voltage (Unloaded)I O = 0
q 5V V OD2Differential Driver Output Voltage (With Load)R = 50Ω, (RS422)
q 2V R = 27Ω, (RS485) (Figure 1)q 1.5
5V ∆V OD Change in Magnitude of Driver Differential
R = 27Ω or R = 50Ω (Figure 1)q 0.2V Output Voltage for Complementary Output States V OC Driver Common-Mode Output Voltage
R = 27Ω or R = 50Ω (Figure 1)q 3V ∆|V OC |Change in Magnitude of Driver Common-Mode R = 27Ω or R = 50Ω (Figure 1)q 0.2
V Output Voltage for Complementary Output States V INH Input High Voltage DI, DE, RE q 2.0
V V INL Input Low Voltage DI, DE, RE q 0.8
V I IN1Input Current
DI, DE, RE
q ±2µA I IN2Input Current (A, B)
V CC = 0V or 5.25V, V IN = 12V q 1.0mA V CC = 0V or 5.25V, V IN = –7V q –0.8mA V TH Differential Input Threshold Voltage for Receiver –7V ≤ V CM ≤ 12V q –0.2
0.2
V ∆V TH Receiver Input Hysteresis V CM = 0V
q 60
mV V OH Receiver Output High Voltage I O = –4mA, V ID = 0.2V q 3.5
V V OL Receiver Output Low Voltage
I O = 4mA, V ID = –0.2V
q 0.4V I OZR Three-State Output Current at Receiver V CC = Max 0.4V ≤ V O ≤ 2.4V q ±1
µA I CC
Supply Current
No Load; DI = GND or V CC Outputs Enabled q 1.8 2.3mA Outputs Disabled q 1.7
2.3
mA R IN Receiver Input Resistance
–7V ≤ V CM ≤ 12V q 12
k ΩI OSD1Driver Short-Circuit Current, V OUT = High V O = –7V q 250mA I OSD2Driver Short-Circuit Current, V OUT = Low V O = 10 V q 250mA I OSR
Receiver Short-Circuit Current
0V ≤ V O ≤ V CC
q
7
85mA
V CC = 5V (Notes 2, 3), unless otherwise noted.
ELECTRICAL C C HARA TERISTICS
C D Consult factory for Military grade parts.
3
149aaSYMBOL PARAMETER
CONDITIONS
MIN TYP MAX UNITS
t PLH Driver Input to Output R DIFF = 54Ω, C L1 = C L2 = 100pF q 103050ns
(Figures 2, 5)
t PHL Driver Input to Output R DIFF = 54Ω, C L1 = C L2 = 100pF q 10
3050ns (Figures 2, 5)
t SKEW Driver Output to Output R DIFF = 54Ω, C L1 = C L2 = 100pF q 4
10ns (Figures 2, 5)
t r , t f
Driver Rise or Fall Time
R DIFF = 54Ω
, C L1 = C L2 = 100pF q 51525ns (Figures 2, 5)
t ZH Driver Enable to Output High C L = 100pF (Figures 4, 6) S2 Closed q 4070ns t ZL Driver Enable to Output Low C L = 100pF (Figures 4, 6) S1 Closed q 4070ns t LZ Driver Disable Time from
Low C L = 15pF (Figures 4, 6) S1 Closed q 4070ns t HZ Driver Disable Time from High C L = 15pF (Figures 4, 6) S2 Closed
q 4070ns t
PLH Receiver Input to Output R DIFF = 54Ω, C L1 = C L2 = 100pF (Figures 2, 7)q 152550ns t PHL Receiver Input to Output R DIFF = 54Ω, C L1 = C L2 = 100pF (Figures 2, 7)q 20
3055ns t SKEW | t PLH – t PHL |
R DIFF = 54Ω, C L1 = C L2 = 100pF (Figures 2, 7)q 515ns Differential Receiver Skew
t ZL Receiver Enable to Output Low C L = 15pF (Figures 3, 8) S1 Closed
q 3045ns t ZH Receiver Enable to Output High C L = 15pF (Figures 3, 8) S2 Closed q 3045ns t LZ Receiver Disable from Low C L = 15pF (Figures 3, 8) S1 Closed q 3045ns t HZ Receiver Disable from High
C L = 15pF (Figures 3, 8) S2 Closed
q
30
45
ns
S U
G C C HARA TERISTICS
WITCHI V CC = 5V (Notes 2, 3), unless otherwise noted.
The q denotes specifications which apply over the operating temperature range.
Note 1: Absolute Maximum Ratings are those values beyond which the safety of the device cannot be guaranteed.
Note 2: All currents into device pins are positive. All currents out of device pins are negative. All voltages are referenced to device ground unless otherwise specified.
Note 3: All typicals are given for V CC = 5V and T A = 25°C.
C C HARA TERISTICS
U W
A TYPICAL PERFOR CE Receiver Output High Voltage vs Temperature
Receiver Output Low Voltage vs Output Current
Receiver Output High Voltage vs Output Current
OUTPUT VOLTAGE (V)
0O U T P U T C U R R E N T (m A )
16 1.0
1485 G01
80.5
1.52432
2.0
412202836OUTPUT VOLTAGE (V)
5
0O U T P U T C U R R E N T (m A )
–81485 G02
–443–12–162
–2–6–10–14
–18TEMPERATURE (°C)
–50
O U T P U T V O L T A G E (V )
501485 G03
–25
125
025
75100
4
C C HARA TERISTICS
U W
A TYPICAL PERFOR CE Driver Differential Output Voltage vs Temperature
TEMPERATURE (°C)
–50
0O U T P U T V O L T A G E (V )
0.10.30.40.5500.91485 G04
0.2–25
125
0.60.7
0.8025
75
100
OUTPUT VOLTAGE (V)
00
O U T P U T C U R R E N T (m A )
322
1485 G05
161
348
64
路障灯4
TEMPERATURE (°C)
–50
1.6D I F F E R E N T I A L V O L T A G E (V )
2.0
50
1485 G06
1.8
–25
125
2.2
2.4
02575
100Driver Differential Output Voltage vs Output Current
Receiver Output Low Voltage vs Temperature
Driver Output High Voltage vs Output Current
TTL Input Threshold vs Temperature
Driver Output Low Voltage vs Output Current
OUTPUT VOLTAGE (V)
00
O U T P U T C U R R E N T (m A )
40
2
1485 G07
20
1
36080
4
OUTPUT VOLTAGE (V)
00
O U T P U T C U R R E N T (m A )
–482
1485 G08
–241
3–72
–96
4
TEMPERATURE (°C)
–50
1.55
I N P U T T H R E S H O L D V O L T A G E (V )
50
1485 G09
1.57
–25
125
1.61
1.63
02575
100Receiver | t PLH – t PHL | vs Temperature
Supply Current vs Temperature
Driver Skew vs Temperature
TEMPERATURE (°C)
–50
1T I M E (n s )
3
50
1485 G102
–25
125
45
02575
100TEMPERATURE (°C)
–50
1T I M E (n s )
350
1485 G112
–25
125
4
5
02575
100TEMPERATURE (°C)
–50
1.4S U P P L Y C U R R E N T (m A )
1.6
50
1485 G12
1.5
–25
125
1.7
1.8
02575100
5
PI FU CTIO S
U
U U RO (Pin 1): Receiver Output. If the receiver output is enabled (RE low), then if A > B by 200mV, RO will be high.If A < B by 200mV, then RO will be low.
RE (Pin 2): Receiver Output Enable. A low enables the receiver output, RO. A high input forces the receiver output into a high impedance state.
DE (Pin 3): Driver Output Enable. A high on DE enables the driver outputs, A and B. A low input will force the driver outputs into a high impedance state.
DI (Pin 4): Driver Input. If the driver outputs are enabled (DE high), then a low on DI forces the driver outputs A low and B high. A high on DI will force A high and B low.GND (Pin 5): Ground Connection.A (Pin 6): Driver Output/Receiver Input.B (Pin 7): Driver Output/Receiver Input.
V CC (Pin 8): Positive Supply. 4.75V ≤ V CC ≤ 5.25V.
TEST CIRCUITS
Figure 3. Receiver Timing Test Load
V CC
RECEIVER OUTPUT
Figure 4. Driver Timing Test Load
V CC
OUTPUT UNDER TEST
A
B
1485 F01
DI
1485 F02
RO Figure 1. Driver DC Test Load
Figure 2. Driver/Receiver Timing Test Circuit
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