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413

RXI

RIS

GND

BUSL1

RIDD

STC

BUSL2

D PACKAGE

(TOP VIEW)

710

VDD

TXI

89BA T

TSS721A

https://www.wendangku.net/doc/d716087052.html, SLAS222B–APRIL1999–REVISED NOVEMBER2010

METER-BUS TRANSCEIVER

Check for Samples:TSS721A

FEATURES

?Meter-Bus Transceiver(for Slave)Meets

Standard EN1434-3

?Receiver Logic With Dynamic Level

Recognition

?Adjustable Constant-Current Sink via Resistor

?Polarity Independent

?Power-Fail Function

?Module Supply Voltage Switch

? 3.3-V Constant Voltage Source

?Remote Powering

?Up to9600Baud in Half Duplex for UART

Protocol

?Slave Power Support

–Supply From Meter-Bus via Output VDD

–Supply From Meter-Bus via Output VDD or

From Backup Battery

–Supply From Battery–Meter-Bus Active for

Data Transmission Only

DESCRIPTION

TSS721A is a single chip transceiver developed for Meter-Bus standard(EN1434-3)applications.

The TSS721A interface circuit adjusts the different potentials between a slave system and the Meter-Bus master.The connection to the bus is polarity independent and supports full galvanic slave isolation with optocouplers.

The circuit is supplied by the master via the bus.Therefore,this circuit offers no additional load for the slave battery.A power-fail function is integrated.

The receiver has dynamic level recognition,and the transmitter has a programmable current sink.

A3.3-V voltage regulator,with power reserve for a delayed switch off at bus fault,is integrated.

Table1.ORDERING INFORMATION(1)(2)

T A PACKAGE ORDERABLE PART NUMBER 0°C to70°C SOIC–D Reel of2500TSS721ADR

(1)For the most current package and ordering information,see the Package Option Addendum at the end of this document,or see the TI

web site at https://www.wendangku.net/doc/d716087052.html,.

(2)Package drawings,thermal data,and symbolization are available at https://www.wendangku.net/doc/d716087052.html,/packaging.

Please be aware that an important notice concerning availability,standard warranty,and use in critical applications of Texas

Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

PRODUCTION DATA information is current as of publication date.Copyright?1999–2010,Texas Instruments Incorporated Products conform to specifications per the terms of the Texas

Instruments standard warranty.Production processing does not

necessarily include testing of all parameters.

BAT RIDD

STC

VS VDD VB

PF BUSL1 TX

GND RIS BUSL2 TXI

RX RXI SC

TSS721A

SLAS222B–APRIL1999–REVISED https://www.wendangku.net/doc/d716087052.html,

FUNCTIONAL DESCRIPTION

Figure1.Functional Schematic

Table2.Terminal Functions

TERMINAL

DESCRIPTION

NAME NO.

BUSL21Meter-Bus

VB2Differential bus voltage after rectifier

STC3Support capacitor

RIDD4Current adjustment input

PF5Power fail output

SC6Sampling capacitor

TXI7Data output inverted

TX8Data output

BAT9Logic level adjust

VS10Switch for bus or battery supply output

VDD11Voltage regulator output

RX12Data input

RXI13Data input inverted

RIS14Adjust input for modulation current

GND15Ground

BUSL116Meter-Bus

2Submit Documentation Feedback Copyright?1999–2010,Texas Instruments Incorporated

Product Folder Link(s):TSS721A

BUSL1BUSL2V T V V TX

V I SC

C = 30 pF typ BUSL1-BUSL2V = 25V ,f = 1 MHz

B meas I =SCdisharge I SCcharge 40 (typ)TSS721A

https://www.wendangku.net/doc/d716087052.html, SLAS222B –APRIL 1999–REVISED NOVEMBER 2010

Data Transmission,Master to Slave

The mark level on the bus lines V BUS =MARK is defined by the difference of BUSL1and BUSL2at the slave.It

is dependent on the distance of Master to Slave,which affects the voltage drop on the wire.To make the

receiver independent,a dynamic reference level on the SC pin is used for the voltage comparator TC3(see

Figure 2).

Figure 2.Data Transmission,Master to Slave

A capacitor C SC at pin SC is charged by a current I SCcharge and is discharged with a current I SCdischarge where:

(1)

This ratio is necessary to run any kind of UART protocol independent of the data contents.(for example,if an

11-bit UART protocol is transmitted with all data bits at 0and only the stop bit at 1).There must be sufficient time

to recharge the capacitor C SC .The input level detector TC3detects voltage modulations from the master,

V BUS =SPACE/MARK conditions,and switches the inverted output TXI and the non-inverted output TX.

Product Folder Link(s):TSS721A

VB BUSL1

GND BUSL2R RIS

RIS RX

RXI

V I BUS V RXI

V RX I = I + I MC MS CS3

I MC

)

RIS W V =Voltage on pin RIS R = Programming resistor I = Programmable current I = Modulation current I = Modulation supply current (220 μA typ)

RIS RIS CS3MC MS R =RIS =V RIS I CS3V RIS I –I MC MS TSS721A

SLAS222B –APRIL 1999–REVISED NOVEMBER https://www.wendangku.net/doc/d716087052.html,

Data Transmission,Slave to Master

The device uses current modulation to transmit information from the slave to the master while the bus voltage

remains constant.The current source CS3modulates the bus current and the master detects the modulation.

The constant current source CS3is controlled by the inverted input RXI or the non-inverted input RX.The current

source CS3can be programmed by an external resistor R RIS .The modulation supply current I MS flows in addition

to the current source CS3during the modulation time.

Figure 3.Data Transmission,Slave to Master

Because the TSS721A is configured for half-duplex only,the current modulation from RX or RXI is repeated

concurrently as ECHO on the outputs TX and TXI.If the slave,as well as the master,is trying to send

information via the lines,the added signals appear on the outputs TX and TXI,which indicates the data collision

to the slave (see Figure 1).

The bus topology requires a constant current consumption by each connected slave.

To calculate the value of the programming resistor R RIS ,use the formula shown in Figure 4.

Figure 4.Calculate Programming Resistor R RIS

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Product Folder Link(s):TSS721A

R= 25 RID V

RIDD

STC

= 25

RIDD

I+ I

STC_use IC1

(

BUS

34567(V)

STC

TSS721A

https://www.wendangku.net/doc/d716087052.html, SLAS222B–APRIL1999–REVISED NOVEMBER2010 Slave Supply,3.3V

The TSS721A has an internal3.3-V voltage regulator.The output power of this voltage regulator is supplied by the storage capacitor C STC at pin STC.The storage capacitor C STC at pin STC is charged with constant current I STC_use from the current source CS1.The maximum capacitor voltage is limited to REF1.The charge current I STC has to be defined by an external resistor at pin RIDD.

The adjustment resistor R RIDD can be calculated using Equation2.

(2)

Where,

I STC=current from current source CS1

I STC_use=charge current for support capacitor

I CI=internal current

V RIDD=voltage on pin RIDD

R RIDD=value of adjustment resistor

The voltage level of the storage capacitor C STC is monitored with comparator TC1.Once the voltage V STC reaches V VDD_on,the switch S VDD connects the stabilized voltage V VDD to pin VDD.VDD is turned off if the voltage V STC drops below the V VDD_off level.

Voltage variations on the capacitor C STC create bus current changes(see Figure5).

Figure5.Single Mode Bus Load

At a bus fault the shut down time of VDD(t off)in which data storage can be performed depends on the system current I VDD and the value of capacitor C STC.See Figure6,which shows a correlation between the shutdown of the bus voltage V BUS and V DD_off and t off for dimensioning the capacitor.

The output VS is meant for slave systems that are driven by the bus energy,as well as from a battery should the bus line voltage fail.The switching of VS is synchronized with VDD and is controlled by the comparator TC1.An external transistor at the output VS allows switching from the Meter-Bus remote supply to battery.

Product Folder Link(s):TSS721A

V V V V V V STC

VDDoff off STC VDD CI1

V –V t =C I +I TSS721A

SLAS222B –APRIL 1999–REVISED NOVEMBER https://www.wendangku.net/doc/d716087052.html,

Power On/Off

Figure 6.Power On/Off Timing

Power Fail Function

Because of the rectifier bridge BR at the input,BUSL1,and BUSL2,the TSS721A is polarity independent.The

pin VB to ground (GND)delivers the bus voltage V VB less the voltage drop over the rectifier BR.The voltage

comparator TC2monitors the bus voltage.If the voltage V VB >V STC +0.6V,then the output PF =1.The output

level PF =0(power fail)provides a warning of a critical voltage drop to the microcontroller to save the data

immediately.

6Submit Documentation Feedback

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TSS721A https://www.wendangku.net/doc/d716087052.html, SLAS222B–APRIL1999–REVISED NOVEMBER2010

ABSOLUTE MAXIMUM RATINGS

over operating free-air temperature range(unless otherwise noted)

V MB Voltage,BUSL1to BUSL2±50V

RX and RXI–0.3V to5.5V

V I Input voltage range

BAT–0.3V to5.5V

T J Operating junction temperature range–25°C to150°C

T A Operating free-air temperature range–25°C to85°C

T STG Storage temperature range–65°C to150°C Power derating factor,junction to ambient8mW/°C RECOMMENDED OPERATING CONDITIONS(1)

MIN MAX UNIT

Receiver10.842

V MB Bus voltage,|BUSL2–BUSL1|V

Transmitter1242

VB(receive mode)9.3

V I Input voltage V

BAT(2) 2.5 3.8

R RIDD RIDD resistor1380kΩ

R RIS RIS resistor100Ω

T A Operating free-air temperature–2585°C

(1)All voltage values are measured with respect to the GND terminal unless otherwise noted.

(2)V BAT(max)≤V STC–1V

ELECTRICAL CHARACTERISTICS(1)

over operating free-air temperature range(unless otherwise noted)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT ΔV BR Voltage drop at rectifier BR I BUS=3mA 1.5V

Voltage drop at current

ΔV CS1R RIDD=13kΩ 1.8V source CS1

R RIDD=13kΩ3

V STC=6.5V,

I BUS BUS current mA

I MC=0mA R

=30kΩ 1.5

RIDD

ΔI BUS BUS current accuracyΔV BUS=10V,I MC=0mA,R RIDD=13kΩto30kΩ2%

I CC Supply current V STC=6.5V,I MC=0mA,V BAT=3.8V,R RIDD=13kΩ(2)650μA

V STC=6.5V,I MC=0mA,V BAT=3.8V,R RIDD=13kΩ,

I CI1CI1current350μA

V BUS=6.5V,RX/RXI=off(2)

I BAT BAT current–0.50.5μA

I BAT+I VDD BAT plus VDD current V BUS=0V,V STC=0V–0.50.5μA

V VDD VDD voltage–I VDD=1mA,V STC=6.5V 3.1 3.4V

R VDD VDD resistance–I VDD=2to8mA,V STC=4.5V5Ω

V DD=on,VS=on 5.6 6.4

V STC STC voltage V DD=off,VS=off 3.8 4.3V

I VDD

R RIDD=30kΩ0.65 1.1

I STC_use STC current V STC=5V mA

R RIDD=13kΩ 1.85 2.4

V RIDD RIDD voltage R RIDD=30kΩ 1.23 1.33V

V VS VS voltage V DD=on,I VS=–5μA V STC–0.4V STC V

R VS VS resistance V DD=off0.31MΩ

V VB=V STC+0.8V,I PF=–100μA V BAT–0.6V BAT

V PF PF voltage V STC=6.5V V VB=V STC+0.3V,I PF=1μA00.6V

V VB=V STC+0.3V,I PF=5μA00.9

(1)All voltage values are measured with respect to the GND terminal,unless otherwise noted.

(2)Inputs RX/RXI and outputs TX/TXI are open,I CC=I CI1+I CI2

Copyright?1999–2010,Texas Instruments Incorporated Submit Documentation Feedback7

Product Folder Link(s):TSS721A

TSS721A

SLAS222B–APRIL1999–REVISED https://www.wendangku.net/doc/d716087052.html,

ELECTRICAL CHARACTERISTICS(1)(continued)

over operating free-air temperature range(unless otherwise noted)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT t on Turn-on time C STC=50μF,Bus voltage slew rate:1V/μs3s

RECEIVER SECTION ELECTRICAL CHARACTERISTICS(1)

over operating free-air temperature range(unless otherwise noted)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

MARK MARK–

V T See Figure2V

–8.2 5.7

V SC SC voltage V VB V

I SCcharge SC charge current V SC=24V,V VB=36V–15–40μA

–0.033×

I SCdischarge SC discharge current V SC=V VB=24V0.3μA

I SCcharge

High-level output voltage V BAT–

V OH I TX/I TXI=–100μA(see Figure2)V BAT V (TX,TXI)0.6

I TX/I TXI=100μA00.5

Low-level output voltage

V OL V (TX,TXI)I

=1.1mA0 1.5

I TX

TX,TXI current V TX=7.5,V VB=12V,V STC=6V,V BAT=3.8V10μA

I TXI

(1)All voltage values are measured with respect to the GND terminal,unless otherwise noted.

TRANSMITTER SECTION ELECTRICAL CHARACTERISTICS(1)

over operating free-air temperature range(unless otherwise noted)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT I MC MC voltage R RIS=100Ω11.519.5mA

R RIS=100Ω 1.4 1.7

V RIS RIS voltage V

R RIS=1000Ω 1.5 1.8

V BAT–

V IH High-level input voltage(RX,RXI)See Figure3,see(2) 5.5V

0.8

V IL Low-level input voltage(RX,RXI)See Figure300.8V

V RX=V BAT=3V,V VB=V STC=0V-0.50.5

I RX RX currentμA

V RX=0V,V BAT=3V,V STC=6.5V-10-40

V RXI=V BAT=3V,V VB=V STC=0V1040

I RXI RXI currentμA

V RXI=V BAT=3V,V STC=6.5V1040

(1)All voltage values are measured with respect to the GND terminal,unless otherwise noted.

(2)V IH(max)=5.5V is valid only when V STC>=6.5V.

8Submit Documentation Feedback Copyright?1999–2010,Texas Instruments Incorporated

Product Folder Link(s):TSS721A

Meter-Bus

C - system stabilising capacitor

C - support capacitor

C - sampling capacitor

C - stabilising capacitor (100 nF)

C :C >= 4:1SSC STC SC VD

D STC VDD R - slave-current adjustment resistor R - modulation-current resistor RL1,RL2 - protection resistors R - discharge resistor (100 k recommended)

RIDD RIS load W TSS721A

https://www.wendangku.net/doc/d716087052.html, SLAS222B –APRIL 1999–REVISED NOVEMBER 2010

APPLICATION INFORMATION

NOTE:Transistor T1should be a BSS84.

Figure 7.Basic Application Circuit Using Support Capacitor C STC >50μF

Figure 8.Basic Application Circuit for Supply From Battery

Copyright ?1999–2010,Texas Instruments Incorporated Submit Documentation Feedback

Product Folder Link(s):TSS721A

TSS721A

SLAS222B–APRIL1999–REVISED https://www.wendangku.net/doc/d716087052.html,

Meter-Bus NOTE:R DSon of the transistor T1(BSS84)at low battery voltage must be considered during application design.

Figure9.Basic Applications for Different Supply Modes

Figure10.Basic Optocoupler Application

10Submit Documentation Feedback Copyright?1999–2010,Texas Instruments Incorporated

Product Folder Link(s):TSS721A

PACKAGING INFORMATION

(1) The marketing status values are defined as follows:

ACTIVE: Product device recommended for new designs.

LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.

NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.

PREVIEW: Device has been announced but is not in production. Samples may or may not be available.

OBSOLETE: TI has discontinued the production of the device.

(2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check https://www.wendangku.net/doc/d716087052.html,/productcontent for the latest availability information and additional product content details.

TBD: The Pb-Free/Green conversion plan has not been defined.

Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.

Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.

Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material)

(3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.

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