Part: SIT3088E

Type: Half-Duplex RS-485/RS-422 Transceiver

Description: 3.0V–5.5V wide power supply, ±15kV HBM ESD-protected, 14Mbps half-duplex RS-485/RS-422 transceiver with 1/8 unit load allowing up to 256 transceivers on the bus.

Operating Conditions:

• Supply voltage: 3.0–5.5 V
• Operating temperature: -40 to 125 °C
• Data transmission rate: Up to 14Mbps
• Bus load: 1/8 unit load (up to 256 transceivers)

Absolute Maximum Ratings:

• Max supply voltage: +6.5 V
• Max receiver input voltage: -15 to +15 V
• Max storage temperature: -60 to 150 °C

Key Specs:

• Differential Driver Output (no load): 3–5.5 V
• Driver Short-circuit Output Current: ±250 mA (short-circuit to 0V12V or -7V0V)
• Receiver Input Current (A, B): -100 μA to 125 μA (DE=0V, VCC=0 or 3.3/5V, VIN=-7V to 12V)
• Receiver Input Resistance: 96 kΩ
• Input Hysteresis Voltage: 10 mV (min)
• Supply Current (operating): 240 μA (typ, VCC=3.3V, /RE=0V, DE=0V)
• Shutdown Current: 0.2 μA (typ, VCC=3.3V or 5V, /RE=VCC, DE=0V)
• ESD Protection (HBM): ±15kV

Features:

• 3.0V~5.5V Wide Power Range, Half-Duplex
• ESD Protection for RS-485 I/O Pins ±15kV, Human Body Model
• Bus Fault Tolerance and Withstand Voltage Reach ±15V
• 1/8 Unit Load, Allow Up to 256 Transceivers on the Bus
• Driver Short-Circuit Output Protection
• Low Power Off Function
• Receiver Open-Circuit Failure Protection
• Strong Anti-Noise Ability
• Integrated Transient Voltage Suppression Function
• Data transmission up to 14Mbps in an electric noise environment

Applications:

• Bus Networking
• Hand in hand Networking (daisy chain topology)
• Bus port protection schemes

Package:

• SOP8
• DIP8
• MSOP8/8 μ MAX/VSSOP8
• DFN3*3-8

• 3.0V~5.5V Wide Power Range, Half-Duplex
• ESD Protection for RS-485 I/O Pins ±15kV, Human Body Model
• Bus Fault Tolerance and Withstand Voltage Reach ±15V
• 1/8 Unit Load , Allow Up to 256 Transceivers on the Bus
• Driver Short-Circuit Output Protection
• Low Power Off Function
• Receiver Open-Circuit Failure Protection
• Strong Anti-Noise Ability
• Integrated Transient Voltage Suppression Function
• Data transmission up to 14Mbps in an electric noise environment
• Available in SOP8, DIP8, MSOP8/8 μ MAX/VSSOP8 and DFN3*3-8 packages

• 4.1 Bus Networking: SIT3088E RS485 transceiver is designed for bidirectional data communication on multi-point bus transmission line. Figure 9 shows a typical network application circuit. These devices can also be used as linear repeaters with cables longer than 4000 feet. In order to reduce reflection, terminal matching should be carried out at both ends of the transmission line with its characteristic impedance, and the length of branch lines outside the main line should be as short as possible.

Figure 9 Bus type RS485 half-duplex communication network

• 4.2 Hand in hand Networking: also known as daisy chain topology, is the standard and specification of RS485 bus wiring, and is the RS485 bus topology recommended by TIA and other organizations. The wiring mode is that the main control equipment and a plurality of slave control equipment form a hand-held connection mode, as shown in Figure 10, and the hand-held mode is no branches. This wiring mode has the advantages of small signal reflection and high communication success rate.
• 4.3 Bus port protection: in severe environment, RS485 communication port is usually provided with electrostatic protection, lightning surge protection and other additional protection, and even the plan to prevent 380V market electricity access is needed to avoid the damage of intelligent instrument and industrial control host. Figure 11 shows three common RS485 bus port protection schemes. The first is the scheme of three-level protection by connecting TVS devices in parallel with A,B port to the protective ground, TVS devices in parallel with A,B port, thermistor in series with A,B port, gas discharge tube in parallel to the protective ground; the second is the scheme of three-level protection by connecting TVS in parallel with A,B port to the ground, thermistor in series with A,B port, and varistor in parallel with A,B port; the third is the scheme of three-level protection by connecting AB with pull-up or pull-down resistor to power and ground respectively, connecting TVS between A & B, A or B port connecting thermistor.

Figure10 Hand in hand RS485 half-duplex communication network

SIT3088ETK Pinout

Package: DFN-8-EP (3×3 mm)

Notes

• This is an RS-485 transceiver IC in an 8-pin DFN package with exposed pad.
• Pin 5 (GND) and exposed pad (EP) are both connected to ground.
• Pins A and B form the differential RS-485 bus interface.
• RE (pin 2) and DE (pin 3) are active-low and active-high control signals respectively for half-duplex operation.

• PARAMETER SYMBOL CONDITION MIN. TYP. MAX. UNIT
• Differential Driver Output (No load) V OD1 3 5.5 V
• Differential Driver Output V OD2 Figure 2, RL= 54 Ω , VCC=3.3V 1.5 VCC V
• Differential Driver Output V OD2 Figure 2, RL= 54 Ω , VCC=5V 1.5 VCC V
• Change in Magnitude of Driver Differential Output Voltage (NOTE1) ∆ V OD Figure 2, RL= 54 Ω 0.2 V
• Driver Common-Mode Output Voltage V OC Figure 2, RL= 54 Ω 3 V
• Change in Magnitude of Common-Mode Output Voltage (NOTE1) ∆ V OC Figure 2, RL= 54 Ω 0.2 V
• Input High Voltage V IH DE, DI, /RE 2 V
• Input Low Voltage V IL DE, DI, /RE 0.8 V
• Logic Input Current I IN1 DE, DI, /RE -2 2 μ A
• Output Short-circuit Current, Short-circuit to High I OSD1 short-circuit to 0V~12V 250 mA
• Output Short-circuit Current, Short-circuit to Low I OSD2 short-circuit to -7V~0V -250 mA

(Unless otherwise noted, Temp=TMIN~TMAX, Temp=25 °C ).

NOTE1: ∆ VOD and ∆V OC are the changes in VOD and VOC, respectively, when the DI input changes state.

• 4.1 Bus Networking: SIT3088E RS485 transceiver is designed for bidirectional data communication on multi-point bus transmission line. Figure 9 shows a typical network application circuit. These devices can also be used as linear repeaters with cables longer than 4000 feet. In order to reduce reflection, terminal matching should be carried out at both ends of the transmission line with its characteristic impedance, and the length of branch lines outside the main line should be as short as possible.

Figure 9 Bus type RS485 half-duplex communication network

• 4.2 Hand in hand Networking: also known as daisy chain topology, is the standard and specification of RS485 bus wiring, and is the RS485 bus topology recommended by TIA and other organizations. The wiring mode is that the main control equipment and a plurality of slave control equipment form a hand-held connection mode, as shown in Figure 10, and the hand-held mode is no branches. This wiring mode has the advantages of small signal reflection and high communication success rate.
• 4.3 Bus port protection: in severe environment, RS485 communication port is usually provided with electrostatic protection, lightning surge protection and other additional protection, and even the plan to prevent 380V market electricity access is needed to avoid the damage of intelligent instrument and industrial control host. Figure 11 shows three common RS485 bus port protection schemes. The first is the scheme of three-level protection by connecting TVS devices in parallel with A,B port to the protective ground, TVS devices in parallel with A,B port, thermistor in series with A,B port, gas discharge tube in parallel to the protective ground; the second is the scheme of three-level protection by connecting TVS in parallel with A,B port to the ground, thermistor in series with A,B port, and varistor in parallel with A,B port; the third is the scheme of three-level protection by connecting AB with pull-up or pull-down resistor to power and ground respectively, connecting TVS between A & B, A or B port connecting thermistor.

Figure10 Hand in hand RS485 half-duplex communication network