74ABTL3205

Features:

• 10-bit BTL transceiver
• Drives heavily loaded backplanes with equivalent load impedances down to 10 ohms
• High drive 100mA BTL open collector drivers on B-port
• Allows incident wave switching in heavily loaded backplane buses
• Reduced BTL voltage swing produces less noise and reduces power consumption
• Built-in precision band-gap reference provides accurate receiver thresholds and improved noise immunity
• Compatible with IEEE Futurebus+ or proprietary BTL backplanes
• Controlled output ramp and multiple GND pins minimize ground bounce
• Tight output skew (0.5nsec typical)
• Glitch-free power up/down operation
• Low I_CC current
• Supports live insertion
• High density packaging
• ESD protection exceeds 2000V per MIL STD 883 Method 3015 and 200V per Machine Model


Pinout




Specifications

SYMBOL	PARAMETER		RATING	UNIT
VCC	Supply voltage		0.5 to +7.0	V
VIN	Input voltage	TTL Signals	1.2 to +7.0	V
		BTL Signals	1.2 to +5.5	V
IIN	Input current		18 to +5	mA
VOUT	Voltage applied to output in High output state		0.5 to +VCC	/v
IOUT	Current applied to output in Low output state	A0 - A8	48	mA
		B0 - B8	200	mA
Tamb	Operating free-air temperature range		40 to +85	°C
TSTG	Storage temperature		65 to +150	°C

Description

This transceiver of the 74ABTL3205 is a 10 bit bidirectional transceiver and is intended to provide the electrical interface to a high performance wired-OR bus.

The B-port drivers of the 74ABTL3205 are Low-capacitance open collectors with controlled ramp and are designed to sink 100mA. Precision band gap references on the B-port insure very good margins by limiting the switching threshold to a narrow region centered at 1.55V.

The B-port interfaces of the 74ABTL3205 to "Backplane Transceiver Logic" (See the IEEE 1194.1 BTL standard). BTL features low power consumption by reducing voltage swing (1V p-p, between 1V and 2V) and reduced capacitive loading (<6pF) by placing an internal series diode on the drivers. BTL also provides incident wave switching, a necessity for high performance backplanes.

To support live insertion, OEB is held Low during power on/off cycles to insure glitch free B port drivers. Proper bias for B port drivers during live insertion is provided by the BIAS V pin when at a 5V level while VCC is Low. The BIAS V pin is a low current input which will reverse bias the BTL driver series Schottky diode, and also bias the B port output pins to a voltage between 1.62V and 2.1V. This bias function of the 74ABTL3205 is in accordance with IEEE BTL standard 1194.1. If live insertion is not a requirement, the BIAS V pin should be tied to a V_CC pin.

The LOGIC GND and BUS GND pins of the 74ABTL3205 are isolated inside the package to minimize noise coupling between the BTL and TTL sides. These pins should be tied to a common ground external to the package. The LOGIC VCC and BUS V_CC pins are also isolated internally to minimize noise and may be externally decoupled separately or simply tied together.

This transceiver function of the 74ABTL3205 is intended to operate in a half-duplex mode. Low current in standby mode is obtained by powering down unused circuitry. Likewise, transmit circuitry is powered down when in receive mode and receive circuitry is powered down while in transmit mode.