SN74LVC4245A
OCTAL BUS TRANSCEIVER AND 3.3-V TO 5-V SHIFTER
WITH 3-STATE OUTPUTS
www.ti.com
SCAS375H–MARCH 1994–REVISED MARCH 2005
Switching Characteristics
over recommended operating free-air temperature range, CL = 50 pF (unless otherwise noted) (see Figure 1 and Figure 2)
VCCA = 5 V ± 0.5 V,
VCCB = 2.7 V to 3.6 V
FROM
(INPUT)
TO
(OUTPUT)
PARAMETER
UNIT
MIN
1
MAX
tPHL
tPLH
tPHL
tPLH
tPZL
tPZH
tPZL
tPZH
tPLZ
tPHZ
tPLZ
tPHZ
6.3
6.7
6.1
5
A
B
A
A
B
A
B
ns
ns
ns
ns
ns
ns
1
1
B
1
1
9
OE
OE
OE
OE
1
8.1
8.8
9.8
7
1
1
1
1
5.8
7.7
7.8
1
1
Operating Characteristics
VCCA = 4.5 V to 5.5 V, VCCB = 2.7 V to 3.6 V, TA = 25°C
PARAMETER
TEST CONDITIONS
TYP
UNIT
Outputs enabled
Outputs disabled
39.5
5
Cpd
Power dissipation capacitance per transceiver
CL = 0,
f = 10 MHz
pF
(1)
Power-Up Considerations
TI level-translation devices offer an opportunity for successful mixed-voltage signal design. A proper power-up
sequence always should be followed to avoid excessive supply current, bus contention, oscillations, or other
anomalies caused by improperly biased device pins. Take these precautions to guard against such power-up
problems:
1. Connect ground before any supply voltage is applied.
2. Power up the control side of the device (VCCA for all four of these devices).
3. Tie OE to VCCA with a pullup resistor so that it ramps with VCCA
.
4. Depending on the direction of the data path, DIR can be high or low. If DIR high is needed (A data to B bus),
ramp it with VCCA. Otherwise, keep DIR low.
(1) Refer to the TI application report, Texas Instruments Voltage-Level-Translation Devices, literature number SCEA021.
5
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