A2. INTERFACE RS MAX 485
Neste anexo são apresentadas as caraterísticas elétricas da interface RS MAX 485 e seu diagrama lógico e digramas de conexões.
A2.1 GENERAL DESCRIPTION
The DS75175B is a high speed differential Tri-state bus/line transceiver designed to meet the requeriments of EIA standard RS485 with extended common mode range (+12 V to -7 V ), for multipoint data transmission. In addition, it is compatible with RS-422.
The driver and receiver outputs feature TRI-STATE capability, for the driver outputs, over the entire common mode rabge of +12 V to -7 V. Bus contention or fault situations that cause excessive power dissipation within the device are handled by a thermal shutdown circuit, witch forces the driver outputs into the high impedance state.
DC specifications are guaranteed over the 0 to 70°C temperature and 4,75 V to 5,25 V supply voltage range.
A2.2 FEATURES
• Meets EIA standard RS$*% for multipoint bus transmission and is compatible with RS-422.
• Small outline (SO) package option available for minimum board space. • 22 ns diver propagation delays.
• Single +5 V supply.
• -7 V to +12 V bus common mode range permits ±7 V gruond difference between devices on the bus.
• Thermal shutdown protection.
• Pin out compatible with DS3695/A and SN75176A/B. • 70 mV typical receiver hysteresis.
Abordagem para automação em uma usina açucareira Anexo 2. RSMAX485 140
• High impedance to bus driver in TRI-STATE or with power off, over the entire common mode range allows the unused devices on the bus to be powered down.
• Combined impedance of a driver output and receiver input is less than one RS485 unit load, allowing up to 32 transceivers on the bus.
A2.3 CONNECTION AND LOGIC DIAGRAM
A2.4 ABSOLUTE MAXIMUM RATINGS
If military/aerospace specified devices are required, please contact the national semiconductor sales office/distributors for availability and specifications.
Tabela 1. Absolute maximum rating (see note 1)
Parameter Valores Supply voltage, V c c 7 V
Control input voltages 7 V Driver input voltages 7 V Driver output voltages +15 V/-10 V Receiver input voltages +15V/-10 V Receiver output voltages 5,5 V Continuous power dissipation at 25°C:
* For M package 675 mW (see note 2) - For N package 900 mW (see note 3 )
Storage temperatura range -40°C até 85°C Lead temperature (soldering, 4 seconds) -65°C até 150°C
Note 1: Absolute maximum ratings are those beyond which the safety of the device cannot be guaranteed. They are not meant to imply that the device should be operated at these limits. The tables of electrical condicions provide conditions for atual device operation.
Note 2: Derate linearly at 6,11 mW/°C to 400 mW at 70°C Note 3: Derate linearly at 5,56 mW/°C to 650 mW at 70°C
Abordagem para automação em uma usina açucareira Anexo 2. RS MAX485 141
A2.5 RECOMMENDED OPERATING CONDICIONS
Tabela 2. Recommended operating condicions
Parameter Min Máx Un
V c c Supply voltage 4,75 5,25 V
Voltage at any bus terminal (separate or common mode -7 +12 V
Ta Operating free air temperature
DS75176B 0 +70 °c
DS75176BT -40 +85 °c
VID Differential input voltage (see note) -12 +12 V Note: Diffentail input/output bus voltage is measured at the noninverting terminal A with respect to the inverting terminal B.
A2.6 ELECTRICAL CHARACTERISTICS
Tabela 3. Electrical characteristics, o°c <; ta < 70°c (see notes 1 e 2) Symbol Parameter Conditions Min Typ Máx Un
V o D1
Differencial driver output voltage
(unloaded) lo- = 0 5 V
VoD2 Differencial driver output voltage (with load)
See Figura 2 R = 27 n
1,5 V
AVod
Change in magnitude of driver differential output voltage for complementary output states
0,2 V
V o c
Differencial common mode output
voltage 3 V
A V oc
Change in magnitude of driver common mode output voltage for complementary output states
0,2 V
V,H Input high voltage
Dl, DE, RE, E
2 V
V,L Input low voltage 0,8
VcL Input clamp voltage liN = -18 mA -1,5 IIL Input low current V|L = -0,4 V -200 mA
l|H Input high current V,h = 2,4 V 20 hA l|N Input current DO/RI, DO/RI V c c ^O V, DE = 0 Vou 5,25 VIN = 12 V +1,0 mA
VlN = -7 V -0,8
Vth
Differential input threshold voltage
for receiver -7 V S Vcm < +12 V -0,2 +0,2 V AVjh Receiver input hysteresis Vcm= 0 V 70 mV
Voh Receiver output high voltage Ioh = -400 mA 2,7 V Vol Output low voltage | RO Iol = 16 mA (see note 3) 0,5 V •oZR
Off-state (high impedance) Output current at receiver
Vcc = Max; 0,4 V < V o <2,4
V ±20 mA
R.N Receiver input resistance -7 V < Vcm < +12 V 12 k d.
Icc Supply current No load see note 3
Driver output enabled 55
mA
Driver output disabled 35
I OSD Driver short-circuit output current V0 = -7 V (see note 3)V0 = +12 V (see note 3) -250 mA 250 mA loSR Receiver short-circuit output current V0 = 0 V -15 -85 mA
Abordagem para automação em uma usina açucareira Anexo 2. RSM AX485 142
Note 1: All currents into device pins are positive; all currents out of device pins are negative. All voltage are referenced to device ground unless otherwise especified.
Note 2: All typicals are given for Vcc = 5 V and TA = 70°C
Note 3: All worst case parameters for which note 3 is applied, must be increased by 10% for DS75176BT. The other parameters remain valid for-40°C < TA < 85°C
A2.7 SWITCHING CHARACTERISTCS
Tabela 4. Switching characteristics,Vcc = 5 V, t a = 25°c
Symbol Parameter Conditions Typ Máx Un
tpLH Driver input to output Rld i f f = 60 Q
Cli=C[_2 = 100 pF
12 22 ns
tpHL Driver input to output 17 22 ns tr Driver rise time Rld i f f = 60 Q
Cli=Cl2 = 100 pF (see fig and )
18 ns
tf Driver fall time 18 ns
tzH Driver enable to output high CL = 100 pF (fig 5 and 7) S1 open 29 100 ns tzL Driver enable to output low CL = 100 pF (fig 5 and 7) S2 open 31 60 ns tLZ Driver disable time from low CL = 15 pF (fig 5 and 7) S2 open 13 30 ns
tHz Driver disable time from high CL = 15 pF (fig 5 and 7) S1 open 19 200 ns
tpLH Receiver input to output CL = 15 pF (fig 3 and 8)
S1 and S2 closed
30 37 ns
tpHL Receiver input to output 32 37 ns tzL Receiver enable to output low CL = 15 pF (fig 3 and 9) S2 open 15 20 ns tzH Receiver enable to output high CL = 15 pF (fig 3 and 9) S1 open 11 20 ns tLZ Receiver disable from low CL = 15 pF (fig 3 and 9) S2 open 28 32 ns t H7 Receiver disable from high CL = 15 pF (fig 3 and 9) S1 open 13 35 ns A2.8 AC TEST CIRCUITS
DO- V, DO R v l
1
Figura 2 Figura 3 Receiver_ output Test point 1 m C,. (include probe and JIG :capacitance >1 Kn
All diodes IN918or
IN3064
S2 Note: S1 and S2 load circuit are — closed «e e p t as otheiw ise mentioned
Figura 4 From output
under test
C i (include T r
probe and JIG " p capacitance S2^ 500 Q -A A A .__ S2. “X
Note: Ih le s s otherwise specified the switches are closed
Abordagem para automação em uma usina açucareira Anexo 2. RS MAX485 143
A2.9 SWITCHING TIME WAVEFORMS 3 V Dl DO DÕ Vo- 0 V - -Vo- svT j r 2.3 V J t-2 ,3 V K—tPK 2,3 V “ tPLH - - 2,3 V
Voff = Vco -Vro " 9 0 %
_ j« b j|
^-tr - ► m -
Figura 6. Driver propagation delays and transition times
"V-1.5V 5 V DO DO O'“!"1 normálv low Va Vom
DO, DÕ normally hahÔ^ UL h
O V
Figura 7. Driver enable and disable times
VcN Vet tP H l- X-1.5V 1,5 V- R i , R I 2 . 5 V ■toy f^1 MHr:t<10 ns fesio ns Output •tP L H • OV Input -2,5 V
Note: DifferenfiaHrputvdtage rrsy be resized ty groundR1 and pufercg Rl between+2,5 V and - 2 ,5 V
Figura 8. Receiver propagation delays
3 V RE 0 v 1 5 V R0 OutPU' normally low d Output 0 normally high OV f=1 TiiPfe !tÍ7Õ"ns V ^ --- trtlflrs--- / lJ --- g ta . •1 ,5 V . Va l4—tzN J^1,5V ta1» Vow twz“ ,5 V _
I F
W
10.5 VFigura 9. Receiver enable and disable times A2.10 FUNCTION TABLES
Tabela 5. DS75176B transmitting Tabela 6. DS75176B receiving
Inputs Line condition Out|puts RE OE Dl DO DO X 1 1 No fault 0 1 X 1 0 No fault 1 0 X 0 X X z z X 1 X No fault z z Inputs Outputs RE DE RI-RI Ro 0 0 > +0,2 V 1 0 0 < -0,2 V 0 0 0 Inputs open** 1 1 0 X z
Abordagem para automação em uma usina açucareira Anexo 2. RS MAX485 144
x: Don’t care condition, z: High impedance state
Fault: Improper line conditions causing excessive power dissipation in the driver, such as shorts or bus contention situations.
**: This a fail sale condition
A2.11 TYPICAL APPLICATION
DS3695/DS75176B/DS3696 DS3697/DS3698 >Rt RtÍ > Rt DS3697/DS3698 Rrî DS75176B