SP3458(MaxLinear-SP3485).pdf-资料库

第1页 / 共9页

第2页 / 共9页

第3页 / 共9页

第4页 / 共9页

第5页 / 共9页

第6页 / 共9页

第7页 / 共9页

第8页 / 共9页

Description The SP3485 device is a 3.3V low power half-duplex transceiver that meets the specifications of the RS-485 and RS-422 serial protocols. This device is pin-to-pin compatible with the MaxLinear SP481, SP483 and SP485 devices as well as popular industry standards. The SP3485 can meet the electrical specifications of the RS-485 and RS- 422 serial protocols up to 10Mbps under load. FEATURES ■■ RS-485 and RS-422 transceiver ■■ Operates from a single 3.3V supply ■■ Interoperable with 5.0V logic ■■ Driver/receiver enable ■■ -7V to +12V common-mode input voltage range ■■ Allows up to 32 transceivers on the serial bus ■■ Compatibility with industry standard 75176 pinout ■■ Driver output short-circuit protection Ordering Information - Back Page Block Diagram RO 1 RE 2 DE 3 DI 4 R D SP3485 VCC 8 B7 A6 5 GND 1/9 3.3V Low Power Half-Duplex RS-485 Transceiver with 10Mbps Data RateSP3485REV 2.0.1

Absolute Maximum Ratings These are stress ratings only and functional operation of the device at these ratings or any other above those indicated in the operation sections of the specifications below is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability. VCC ............................................................................... 6.0V Input Voltages Output Voltages Logic ..................................... -0.3V to 6.0V Drivers .................................. -0.3V to 6.0V Receivers ...........................................±15V Drivers ...............................................±15V Receivers .............................. -0.3V to 6.0V Storage Temperature ...................................-65˚C to 150˚C Maximum Junction Temperature, TJ ..........................125˚C Power Dissipation .................................................... 600mW (derate 6.90mW/°C above 70°C) Operating Conditions Package Power Dissipation 8-pin NSOIC ѲJA ................................................ 128.4˚C/W ESD Rating Human Body Model (HBM) .......................................... ±2kV Electrical Characteristics Unless otherwise noted: TAMB = TMIN to TMAX and VCC = 3.3V ±5%. PARAMETERS SP3485 Driver DC Characteristics Differential output voltage Differential output voltage Differential output voltage Change in magnitude of driver differential output voltage for complimentary states Driver common mode output voltage Input high voltage Input low voltage Input current Driver short circuit current VOUT = HIGH Driver short circuit current VOUT = LOW SP3485 Driver AC Characteristics Maximum data rate Driver input to output, tPLH Driver input to output, tPHL Differential driver skew Driver rise or fall time Driver enable to output high Driver enable to output low Driver disable time from low Driver disable time from high Driver enable from shutdown to output high, tPSH Driver enable from shutdown to output low, tPSL Time to shutdown, tSHDN MIN. TYP. MAX. UNITS CONDITIONS 2 1.5 2.0 10 17 17 2 5 35 30 20 20 50 200 Vcc Vcc Vcc 0.2 3 0.8 ±10 ±250 ±250 60 60 10 20 120 120 120 120 250 250 600 Volts Volts Volts Volts Volts Volts Volts µA mA mA Mbps ns ns ns ns ns ns ns ns ns ns ns Unloaded; R = ∞Ω ; Figure 1 With Load; R = 50Ω (RS-422); Figure 1 With Load; R = 27Ω (RS-485); Figure 1 R = 27Ω or R = 50Ω; Figure 1 R = 27Ω or R = 50Ω; Figure 1 Applies to DE, DI, RE Applies to DE, DI, RE Applies to DE, DI, RE -7V ≤ VO ≤ +12V; Figure 8 -7V ≤ VO ≤ +12V; Figure 8 RE = VCC, DE = VCC Figures 2 & 9 Figures 2 & 9 |tDO1- tDO2|, Figures 2 and 10 From 10%-90%; Figures 3 and 10 Figures 4 and 11 Figures 5 and 11 Figures 5 and 11 Figures 4 and 11 CL = 50pF, RL = 500Ω. Figures 4, 5, and 11 Notes 1 and 2 2/9 SP3485REV 2.0.1

Electrical Characteristics (Continued) Unless otherwise noted: TAMB = TMIN to TMAX and VCC = 3.3V ±5%. PARAMETERS SP3485 Receiver DC Characteristics Differential input threshold Input hysteresis Output voltage HIGH Output voltage LOW Three-state (high impedance) output current Input resistance Input current (A, B); VIN = 12V Input current (A, B); VIN = -7V Short circuit current SP3485 Receiver AC Characteristics Maximum data rate Receiver input to output, tPLH Receiver input to output, tPLH Receiver input to output, tPHL Receiver input to output, tPHL Differential receiver skew Receiver enable to output low Receiver enable to output high Receiver disable from low Receiver disable from high Receiver enable from shutdown to output high, tPRSH Receiver enable from shutdown to output low, tPRSL Time to shutdown, tSHDN Power Requirements Supply current , no load Supply current , no load MIN. TYP. MAX. UNITS CONDITIONS -0.2 Vcc-0.4 12 7 10 50 20 40 35 4 10 10 10 10 200 425 300 0.2 0.4 ±1 1.0 -0.8 60 100 70 100 70 60 60 60 60 1800 1800 600 2000 1500 Volts mV Volts Volts µA kΩ mA mA mA Mbps ns ns ns ns ns ns ns ns ns ns ns ns µA µA -7V ≤ VCM ≤ 12V VCM = 0V VID = 200mV, -1.5mA VID = -200mV, 2.5mA 0V ≤ VO ≤ VCC; RE = VCC -7V ≤ VCM ≤ 12V DE = 0V, VCC = 0V or 3.6V, VIN = 12V DE = 0V, VCC = 0V or 3.6V, VIN = -7V 0V ≤ VCM ≤ VCC RE = 0V, DE = 0V Figures 6 and 12 TAMB = 25°C, Vcc = 3.3V, Figures 6 and 12 Figures 6 and 12 TAMB = 25°C, Vcc = 3.3V, Figures 6 and 12 tRSKEW = |tRPHL- tRPLH|, Figures 6 and 12 Figures 7 and 13, S1 closed, S2 open Figures 7 and 13, S2 closed, S1 open Figures 7 and 13, S1 closed, S2 open Figures 7 and 13, S2 closed, S1 open CL = 15pF, RL = 1kΩ. Figures 7 and 13 Notes 1 and 2 RE, DI = 0V or VCC ; DE = VCC RE = 0V, DI = 0V or VCC, DE = 0V NOTES: 1. The transceivers are put into shutdown by gringing RE high and DE low simultaneously for at least 600ns. If the control inputs are in this state for less than 50ns, the device is guaranteed to not enter shutdown. If the enable inputs are held in this state for at least 600ns, the device is assured to be in shutdown. Note that the receiver and driver times increase significantly when coming out of shutdown. 2. This spec is guaranteed by design and bench characterization. 3/9 SP3485REV 2.0.1

Pin Functions Pin Name Description 1 2 3 4 5 6 7 8 RO RE DE DI Receiver output Receiver output enable active LOW Driver output enable active HIGH Driver input GND Ground connection A B Non-inverting driver output / receiver input Inverting driver output / receiver input VCC Positive supply RO 1 RE 2 DE 3 DI 4 R D SP3485 Pinout (Top View) VCC 8 B7 A6 5 GND 4/9 SP3485REV 2.0.1

Test Circuits D VOD Vcc R R VOC GENERATOR (NOTE 1) 50Ω D VCC CL 15pF (NOTE 2) RL 54Ω OUT Figure 1: Driver DC Test Load Circuit Figure 2: Driver Propagation Delay Test Circuit GENERATOR (NOTE 1) 50Ω D VCC CL RL = 60Ω OUT C L = 15pF (NOTE 2) S1 D CL = 50pF (NOTE 2) OUT RL = 110Ω GENERATOR (NOTE 1) 50Ω Figure 3: Driver Differential Output Delay Figure 4: Driver Enable and Disable Timing Circuit, and Transition Time Circuit. Output High VCC RL = 110Ω OUT 0V OR 3V D GENERATOR (NOTE 1) 50Ω S1 C L = 50pF (NOTE 2) GENERATOR (NOTE 1) 50Ω VID R OUT CL = 15pF (NOTE 2) 1.5V 0V Figure 5: Driver Enable and Disable Timing Circuit, Figure 6: Receiver Propagation Delay Test Circuit Output Low 1k C L = 15pF (NOTE 2) S3 1.5V -1.5V VID R GENERATOR (NOTE 1) 50Ω S1 S2 VCC DE = 0 or Vcc DI = 0 or Vcc D A B IOS D -7V to +12V V Figure 7: Receiver Enable and Disable Timing Circuit Figure 8: Driver Short Circuit Current Limit Test NOTES 1: The input pulse is supplied by a generator with the following characteristics: 2: CL includes probe and stray capacitance. PRR = 250kHz, 50% duty cycle, tR < 6.0ns, ZO = 50Ω. 5/9 SP3485REV 2.0.1

Switching Waveforms INPUT Y OUTPUT Z OUTPUT 3V 0V VOH VOL VOH VOL 1.5V tPLH 1.5V tPHL VOM VOM tPHL tPLH VOM VOM VOM = VOH + VOL 2 ≈ 1.5V Figure 9: Driver Propagation Delay Waveforms DE OUTPUT HIGH OUTPUT LOW 3V 0V VOH 0V VCC VOL 1.5V tPZH tPSH tPZL tPSL VOM VOM 1.5V tPHZ tPLZ 0.25V 0.25V VOM = VOH + VOL 2 ≈ 1.5V IN 1.5V 1.5V tDO1 tDO2 90% 90% OUT 50% 10% tTD 50% 10% tTD 3V 0V 2.0V -2.0V Figure 10: Driver Differential Output Delay and Transition Time Waveforms INPUT OUTPUT 3V 0V VCC 0V 1.5V tRPLH 1.5V tRPHL VOM VOM VOM = VCC 2 Figure 11: Driver Enable and Disable Timing Waveforms Figure 12: Receiver Propagation Delay Waveforms RE OUTPUT 3V 0V VOH 0V S1 is open S2 is closed S3 = 1.5V 1.5V tPRHZ 10% 1.5V tPRZH tPRSH S1 is closed S2 is open S3 = -1.5V 1.5V tPRLZ 10% 1.5V tPRZL tPRSL 1.5V 3V 0V VCC VOL RE 1.5V OUTPUT Figure 13: Receiver Enable and Disable Waveforms 6/9 SP3485REV 2.0.1

Description The SP3485 is a member in the family of 3.3V low power half- duplex transceivers that meet the electrical specifications of the RS-485 and RS-422 serial protocols. This device is pin- to-pin compatible with the MaxLinear SP481, SP483 and SP485 devices as well as popular industry standards. The SP3485 feature MaxLinear’s BiCMOS process allowing low power operationwithout sacrificing performance. Driver The driver outputs of the SP3485 are differential outputs meeting the RS-485 and RS-422 standards. The typical voltage output swing with no load will be 0 volts to 3.3 Volts. With a load of 54Ω across the differential outputs, the drivers can maintain greater than 1.5V voltage levels. The driver of the SP3485 has a driver enable control line which is active HIGH. A logic HIGH on DE (pin 3) will enable the differential driver outputs. A logic LOW on the DE (pin 3) will tri-state the driver outputs. The driver of the SP3485 operates up to 10Mbps. The 250mA ISC maximum limit on the driver output allows the SP3485 to withstand an infinite short circuit over the -7.0V to 12V common mode range without catastrophic damage to the IC. Receiver The SP3485 receiver has differential inputs with an input sensitivity of ±200mV. Input impedance of the receiver is 12kΩ minimum. A wide common mode range of -7V to 12V allows for large ground potential differences between systems. The receiver is equipped with a fail-safe feature that guarantees the receiver output will be in a HIGH state when the input is left unconnected. The receiver of the SP3485 operates up to 10Mbps. The receiver of the SP3485 has an enable control line which is active LOW. A logic LOW on RE (pin 2) will enable the differential receiver. A logic HIGH on RE (pin 2) of the SP3485 will disable the receiver. Low Power Shutdown Mode Low-power shutdown mode is initiated by bringing both RE high and DE low. In shutdown, the devices typically draw only 50nA of supply current. RE and DE can be driven simultaneously; the part is guaranteed not to enter shutdown if RE is high and DE is low for less than 50ns. If the inputs are in this state for at least 600ns, the parts are guaranteed to enter shutdown. Enable times tPRZH, tPZH, tPRZL and tPZL assume the part was not in a low-power shutdown state. Enable times tPRSH, tPSH, tPRSL and tPSL assume the parts were shut down. It takes drivers and receivers longer to become enabled from low-power shutdown mode (tPRSH, tPSH, tPRSL, tPSL) than from driver/receiver-disable mode (tPRZH, tPZH, tPRZL, tPZL). RE X X 0 1 RE 0 0 X 1 1 INPUTS OUTPUTS DE 1 1 0 0 DI 1 0 X X B 0 1 A 1 0 High-Z Shutdown Table 1: Transmit Function Truth Table INPUTS OUTPUTS DE X X X 1 0 VA - VB -50mV -200mV Open/Shorted RO 1 0 1 X X High-Z Shutdown Table 2: Receive Function Truth Table 7/9 SP3485REV 2.0.1

Mechanical Dimensions NSOIC8 Top View Side View Front View Drawing No: POD-00000108 Revision: A 8/9 SP3485REV 2.0.1

资料库

SP3458(MaxLinear-SP3485).pdf

相关推荐

树莓派

热门标签

最新资料