74VCX163245
Low Voltage 16-Bit Dual Supply Translating Transceiver
with 3-STATE Outputs
74VCX163245 Low Voltage 16-Bit Dual Supply Translating Transceiver with 3-ST ATE Outputs
General Description
The VCX163245 is a dual supply, 16-bit translating transceiver that is designed for 2 way asynchr onous communication between busses at different supply voltages by
providing true sign al tr ans lati on . T he sup ply r ai ls co nsi st of
, which is a higher po tential rail operating at 2.3 to
V
CCA
3.6V and V
1.65 to 2.7V. (V
proper device opera tion). This dual supply design allows
for translation from 1.8V to 2.5V busses to busses at a
higher potential, up to 3.3V.
The Transmit/Receive (T/R
of data flow. Transmit (active-HIGH) enables data from A
Ports to B Ports; Re ceive (activ e-LOW) en ables data from
B Ports to A Ports. The Ou tput Enable (OE
HIGH, disables both A and B Ports by placing them in a
High-Z cond i t io n. Th e A P ort i nt er fa c es wi t h th e higher voltage bus (2.7 − 3.3V); The B Port interfaces with the lower
voltage bus (1.8 − 2.5V). Also the VCX16 3245 is de sign ed
so that the control pins (T/R
The 74VCX163245 is suit able for mixed voltage applications such as notebook compute rs using a 1.8V CPU and
3.3V peripheral components. It is fabricated with an
Advanced CMOS technology to achieve high speed operation while maintaining low CMOS power dissipation.
, which is the lower potential rail operating at
CCB
must be less than or equal to V
CCB
) input determines the direct ion
) input, when
, OEn) are supplied by V
n
CCA
CCB
Features
■ Bidirectional interface between busses ranging from
Side A Inputs or 3-STATE Outputs
Side B Inputs or 3-STATE Outputs
Connection DiagramTruth T ables
Inputs
OE
T/R
1
1
LLBus B0–B7 Data to Bus A0–A
74VCX163245
LHBus A0–A7 Data to Bus B0–B
HXHIGH Z State on A0–A7, B0–B
Inputs
OE
T/R
2
2
LLBus B8–B15 Data to Bus A8–A
LHBus A8–A15 Data to Bus B8–B
HXHIGH-Z State on A8–A15, B8–B
H = HIGH Voltage Level
L = LOW Voltage Level
X = Immaterial (HIGH or LOW, inputs may not float)
Z = High Impedance
VCX163245 Translator Power Up Sequence Recommendations
To guard against power up problems, some simple guidelines need to b e adhered t o. The VCX16 3245 is de signed
so that the cont rol pin s (T/R
, OEn) are supplied by V
n
Therefore the first recommendation is to begin by powering
up the control side of the device, V
pins should be ramped with or ahead of V
. The OEn control
CCB
CCB
, this will
guard against bus contentions and oscillations as all A Port
and B Port outputs will be disabled. To ensure the high
impedance state during power up or power down, OE
should be tied to V
through a pull up resisto r. The mini-
CCB
mum value of the resistor is determined by the current
sourcing capability of the driver. Second, the T/R
control
n
pins should be placed at logic LOW (0V) level, this will
ensure that the B-sid e b us pi ns are co nfig ure d a s in put s to
help guard against bus conten tion and oscillation s. B-side
.
CCB
Data Inputs should be driven to a valid lo gic level (0V or
V
), this will prevent excessive current draw and oscilla-
CCB
tions. V
V
CCA
proper device oper ation. Upon completion of the se steps
the device can then be config ured for the users desired
n
operation. Following these steps will help to p revent possi-
can then be pow ered up after V
CCA
must be greater than or equal to V
ble damage to the translator device as well as other system
components.
Outputs
Outputs
CCB
to ensure
CCB
7
7
7
15
15
15
, however
Logic Diagrams
Please note that these diagrams are pro v ided only for the underst anding of logic operations and should not be use d to es t im at e propagation delays.
www.fairchildsemi.com2
Absolute Maximum Ratings(Note 2)Recommended Operating
Supply Voltage
V
CCA
V
CCB
−0.5V to +4.6V
−0.5V to V
CCA
DC Input Voltage (VI)−0.5V to +4.6V
DC Output Voltage (V
)
I/O
Outputs 3-STATE−0.5V to +4.6V
Outputs Active (Note 3)
A
n
B
n
DC Input Diode Current (I
< 0V−50 mA
V
I
DC Output Diode Current (I
< 0V−50 mA
V
O
> V
V
O
CC
)
IK
OK
−0.5V to V
−0.5V to V
)
CCA
CCB
+50 mA
+ 0.5V
+ 0.5V
DC Output Source/Sink Current
)±50 mA
(I
OH/IOL
or Ground Current±100 mA
DC V
CC
Supply Pin (I
Storage Temperature (T
or Ground)
CC
) −65°C to +150°C
STG
Conditions
Power Supply (Note 5)
V
CCA
V
CCB
Input Voltage (V
Input/Output Voltage (V
A
n
B
n
Output Current in IOH/I
V
= 3.0V to 3.6V±24 mA
CCA
= 2.3V to 2.7V±18 mA
V
CCA
= 2.3V to 2.7V±18 mA
V
CCB
= 1.65V to 1.95V±6 mA
V
CCB
Free Air Operating Temperature (T
Minimum Input Edge Rate (∆t/∆V)
= 0.8V to 2.0V, VCC = 3.0V10 ns/V
V
IN
Note 2: The “Absolute Maximum Ratings ” are those val ues beyond w hich
the safety of the device cannot be guaranteed. The device should not be
operated at these limits. The parametric values defined in the Electrical
Characteristics tables are not guaranteed at the absolute maximum ratings.
The “Recommend ed O peratin g Cond itions” t able w ill defin e the condit ions
for actual device operation.
Absolute Maximum Rating must be observed.
Note 3: I
O
Note 4: Unused inputs or I/O pin s mu st be held H IGH or L OW. They ma y
not float.
Note 5: Operation requires: V
(Note 4)
) @ OE, T/R0V to V
I
OL
CCB
)
I/O
A
≤ V
CCA
2.3V to 3.6V
1.65V to 2.7V
CCB
0V to V
CCA
0V to V
CCB
−40°C to +85°C
74VCX163245
DC Electrical Characteristics (1.65V < V
SymbolParameterConditions
V
V
V
V
V
V
V
V
I
I
I
I
∆I
IHA
IHB
ILA
ILB
OHA
OHB
OLA
OLB
I
OZ
OFF
CCA/ICCB
CC
HIGH Level Input Voltage A
LOW Level Input Voltage A
HIGH Level Output VoltageIOH =−100 µA1.65–1.95 2.3–2.7 V
HIGH Level Output VoltageIOH =−100 µA1.65–1.95 2.3–2.7 V