SGS Thomson Microelectronics ST485ADR, ST485CN, ST485CDR, ST485CD, ST485BN Datasheet

ST485

LOW POWER RS-485/RS-422 TRANSCEIVER

■LOW QUIESCENT CURRENT: 300μA

■DESIGNED FOR RS-485 INTERFACE APPLICATIONS

■-7V TO 12V COMMON MODE INPUT VOLTAGE RANGE

■DRIVER MAINTAINS HIGH IMPEDANCE IN 3-STATE OR WITH THE POWER OFF

■70mV TYPICAL INPUT HYSTERESIS

■30ns PROPAGATION DELAYS, 5ns SKEW

■OPERATE FROM A SINGLE 5V SUPPLY

■CURRENT LIMITING AND THERMAL SHUTDOWN FOR DRIVER OVERLOAD PROTECTION

■ALLOWS UP TO 64 TRANSCEIVERS ON THE BUS

DESCRIPTION

The ST485 is al low power transceiver for RS-485 and RS-422 communication. Each part contains one driver and one receiver.

This transceiver draw 300μA (typ.) of supply current when unloaded or fully loaded with disabled drivers.

DIP SOP

It operates from a single 5V supply.

Driver is short-circuit current limited and is protected against excessive power dissipation by thermal shutdown circuitry that placed the driver outputs into a high-impedance state. .

The ST485 is designed for bi-directional data communications on multipoint bus transmission line (half-duplex applciations).

ORDERING CODES

	Type	Temperature	Package	Comments
		Range
	ST485CN	0 to 70 °C	DIP-8	50parts per tube / 40tube per box
	ST485BN	-40 to 85 °C	DIP-8	50parts per tube / 40tube per box
	ST485AN	-55 to 125 °C	DIP-8	50parts per tube / 40tube per box
	ST485CD	0 to 70 °C	SO-8 (Tube)	100parts per tube / 20tube per box
	ST485BN	-40 to 85 °C	DIP-8	50parts per tube / 40tube per box
	ST485AD	-55 to 125 °C	SO-8 (Tube)	100parts per tube / 20tube per box
	ST485CDR	0 to 70 °C	SO-8 (Tape & Reel)	2500 parts per reel
	ST485BDR	-40 to 85 °C	SO-8 (Tape & Reel)	2500 parts per reel
	ST485ADR	-55 to 125 °C	SO-8 (Tape & Reel)	2500 parts per reel

March 2002

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ST485

PIN CONFIGURATION

PIN DESCRIPTION

PlN N°	SYMBOL	NAME AND FUNCTION
1	RO	Receiver Output
2	RE	Receiver Output Enable
3	DE	Driver Output Enable
4	DI	Driver Input
5	GND	Ground
6	A	Non-inverting Receiver Input and Non-inverting Driver Output
7	B	Inverting Receiver Input and Inverting Driver Output
8	VCC	Supply Voltage

TRUTH TABLE (DRIVER)					TRUTH TABLE (RECEIVER)
	INPUTS		OUTPUTS			INPUTS		OUTPUT
RE	DE	DI	B	A	RE	DE	A-B	RO
X	H	H	L	H	L	L	≥ +0.2V	H
X	H	L	H	L	L	L	≤ -0.2V	L
X	L	X	Z	Z	L	L	INPUTS OPEN	H
X= Don't Care; Z=High Impedance					H	L	X	Z
					X= Don't Care; Z=High Impedance

ABSOLUTE MAXIMUM RATINGS

Symbol	Parameter	Value
VCC	Supply Voltage	12
VI	Control Input Voltage (RE, DE)	-0.5 to (VCC + 0.5)
VDI	Driver Input Voltage (DI)	-0.5 to (VCC + 0.5)
VDO	Driver Output Voltage (A, B)	± 14
VRI	Receiver Input Voltage (A, B)	± 14
VRO	Receiver Output Voltage (RO)	-0.5 to (VCC + 0.5)

Unit

V

V

V

V

V

V

Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these condition is not implied.

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ST485

DC ELECTRICAL CHARACTERISTICS

(VCC = 5V ± 5%, TA = TMIN to TMAX , unless otherwise specified. Typical values are referred to TA = 25°C) (See Note 1)

Symbol	Parameter	Test Conditions	Min.	Typ. Max.	Unit
VOD1	Differential Driver Output			5	V
	(No Load)

VOD2	Differential Driver Output
	(With Load)
VOD	Change in Magnitude of
	Driver Differential Output
	Voltage for Complementary
	Output States

RL = 27Ω (RS-485)	(See Fig. 1)		1.4	5	V
RL = 50Ω (RS-422)	(See Fig.	1)		5	V
RL = 27Ω or 50Ω (See Fig. 1)				0.2	V

VOC	Driver Common-Mode	RL = 27Ω or 50Ω (See Fig. 1)					3	V
	Output Voltage
VOC	Change in Magnitude of	RL = 27Ω or 50Ω (See Fig. 1)					0.2	V
	Driver Common-Mode
	Output Voltage for
	Complementary Output
	States
VIH	Input High Voltage	RE, DE, DI				2.0		V
VIL	Input Low Voltage	RE, DE, DI					0.8	V
IIN1	Input Current	RE, DE, DI					± 2	μA
IIN2	Input Current (A, B)	VCM = 0V or 5.25V			VDE = 0V		1	mA
		VIN = 12V
		VIN = -7V					-0.8	mA
VTH	Receiver Differential	VCM = -7 to 12V				-0.2	0.2	V
	Threshold Voltage
VTH	Receiver Input Hysteresis	VCM = 0V				70		mV
VOH	Receiver Output High	IO = -4mA	VID = 200mV			3.4		V
	Voltage
VOL	Receiver Output Low	IO = 4mA	VID = -200mV				0.5	V
	Voltage
IOZR	3-State (High Impedance)	VO = 0.4 to 2.4V					± 1	μA
	Output Current at Receiver
RIN	Receiver Input Resistance	VCM = -7 to 12V				24		KΩ
ICC	No Load Supply Current	VRE = 0V or VCC						μA
	(Note 2)	VDE = VCC				400	900
		VDE = 0V				300	500	μA
IOSD1	Driver Short-Circuit Current,	VO = -7 to 12V		(Note 3)		35	250	mA
	VO=High
IOSD2	Driver Short-Circuit Current,	VO = -7 to 12V		(Note 3)		35	250	mA
	VO=Low
IOSR	Receiver Short-Circuit	VO = 0V to VCC				7	95	mA
	Current

Note 1: All currents into device pins are positive; all cuttents out of device pins are negative; all voltages are referenced to device ground unless specified.

Note 2: Supply current specification is valid for loaded transmitters when VDE = 0V Note 3: Applies to peak current. See typical Operating Characteristics.

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ST485

DRIVER SWITCHING CHARACTERISTICS

(VCC = 5V ± 5%, TA = TMIN to TMAX , unless otherwise specified. Typical values are referred to TA = 25°C) (See Note 1)

Symbol	Parameter	Test Conditions		Min.	Typ.	Max.	Unit
tPLH	Propagation Delay Input to	RDIFF = 54Ω	CL1 = CL2 = 100pF	10	30	70	ns
tPHL	Output	(See Fig. 3 and 5)
tSK	Output Skew to Output	RDIFF = 54Ω	CL1 = CL2 = 100pF		5	10	ns
		(See Fig. 3 and 5)
tTLH	Rise or Fall Time	RDIFF = 54Ω	CL1 = CL2 = 100pF	3	15	45	ns
tTHL		(See Fig. 3 and 5)
tPZH	Output Enable Time	CL = 100pF	S2 = Closed		70	90	ns
		(See Fig. 4 and 6)
tPZL	Output Enable Time	CL = 100pF	S1 = Closed		70	90	ns
		(See Fig. 4 and 6)
tPLZ	Output Disable Time	CL = 15pF	S1 = Closed		70	90	ns
		(See Fig. 4 and 6)
tPHZ	Output Disable Time	CL = 15pF	S2 = Closed		70	90	ns
		(See Fig. 4 and 6)

Note 1: All currents into device pins are positive; all cuttents out of device pins are negative; all voltages are referenced to device ground unless specified.

RECEIVER SWITCHING CHARACTERISTICS

(VCC = 5V ± 5%, TA = TMIN to TMAX , unless otherwise specified. Typical values are referred to TA = 25°C) (See Note 1)

Symbol	Parameter	Test Conditions		Min.	Typ.	Max.	Unit
tPLH	Propagation Delay Input to	RDIFF = 54Ω	CL1 = CL2 = 100pF	20	130	230	ns
tPHL	Output	(See Fig. 3 and 7)
tSKD	Differential Receiver Skew	RDIFF = 54Ω	CL1 = CL2 = 100pF		13		ns
		(See Fig. 3 and 7)
tPZH	Output Enable Time	CRL = 15pF	S1 = Closed		20	55	ns
		(See Fig. 2 and 8)
tPZL	Output Enable Time	CRL = 15pF	S2 = Closed		20	55	ns
		(See Fig. 2 and 8)
tPLZ	Output Disable Time	CRL = 15pF	S1 = Closed		20	55	ns
		(See Fig. 2 and 8)
tPHZ	Output Disable Time	CRL = 15pF	S2 = Closed		20	55	ns
		(See Fig. 2 and 8)
fMAX	Maximum Data Rate			2.5			Mbps

Note 1: All currents into device pins are positive; all cuttents out of device pins are negative; all voltages are referenced to device ground unless specified.

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