FXL4TD245 Datasheet, PDF (2/12 Pages) Fairchild Semiconductor – Low Voltage Dual Supply 4-Bit Signal Translator with Configurable Voltage Supplies and Signal Levels and 3-STATE

Functional Diagram
VCCA
VCCB
OE
A 0-3
T/R _0-3
B0-3
Connection Diagram
V_CCA V_CCB
1 16
T/R₀ 2
15 T/R₁
A₀ 3
14 B₀
A₁ 4
A₂ 5
13 B₁
12 B₂
A₃ 6
T/R₃ 7
11 B₃
10 T/R₂
89
GND OE
(Top View)
Pin Assignment
Pin Number
1
2
3–6
7
8
9
10
11–14
15
16
Terminal Name
V_CCA
T/R₀
A₀–A₃
T/R₃
GND
OE
T/R₂
B₃–B₀
T/R₁
V_CCB
Pin Descriptions
Pin Names
Description
OE
Output Enable Input
T/R_n
A_n
B_n
V_CCA
V_CCB
Transmit/Receive Inputs
Side A Inputs or 3-STATE Outputs
Side B Inputs or 3-STATE Outputs
Side A Power Supply
Side B Power Supply
Truth Table
Inputs
OE ^T/R0 ^T/R1 ^T/R2 ^T/R3
Outputs
L L X X X B0 Data to A0 Output
L H X X X A0 Data to B0 Output
L X L X X B1 Data to A1 Output
L X H X X A1 Data to B1 Output
L X X L X B2 Data to A2 Output
L X X H X A2 Data to B2 Output
L X X X L B3 Data to A3 Output
L X X X H A3 Data to B3 Output
H X X X X 3-State
H = HIGH Voltage Level
L = LOW Voltage Level
X = Don't Care
Power-Up/Power-Down Sequencing
FXL translators offer an advantage in that either V_CC
may be powered up first. This benefit derives from the
chip design. When either V_CC is at 0 volts, outputs are in
a HIGH-Impedance state. The control inputs (T/R_n and
OE) are designed to track the V_CCA supply. A pull-up
resistor tying OE to V_CCA should be used to ensure that
bus contention, excessive currents, or oscillations do not
occur during power-up/power-down. The size of the pull-
up resistor is based upon the current-sinking capability
of the OE driver.
The recommended power-up sequence is the following:
1. Apply power to either V_CC.
2. Apply power to the T/R_n inputs (Logic HIGH for A-to-B
operation; Logic LOW for B-to-A operation) and to the
respective data inputs (A Port or B Port). This may
occur at the same time as Step 1.
3. Apply power to other V_CC.
4. Drive the OE input LOW to enable the device.
The recommended power-down sequence is the following:
1. Drive OE input HIGH to disable the device.
2. Remove power from either V_CC.
3. Remove power from other V_CC.
©2006 Fairchild Semiconductor Corporation
FXL4TD245 Rev. 1.0.4
2
www.fairchildsemi.com