NTB0101A All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2015. All rights reserved.
Product data sheet Rev. 1 — 14 July 2015 14 of 19
NXP Semiconductors
NTB0101A
Auto direction sensing dual supply
13.3 Input driver requirements
For correct operation, the device that drives the data I/Os of the NTB0101A must have a
minimum drive capability of 2 mA. See Figure 8
for a plot of typical input current versus
input voltage.
13.4 Power-up
V
CC(A)
must never be higher than V
CC(B)
during operation. However during power-up,
V
CC(A)
V
CC(B)
does not damage the device. Either of the power supplies can be ramped
up first and hence no special power-up sequencing is required. The NTB0101A includes
circuitry that disables all output ports when either V
CC(A)
or V
CC(B)
is switched off.
13.5 Enable and disable
An output enable input (OE) is used to disable the device. Setting OE = HIGH causes all
I/Os to assume the high-impedance OFF-state. The disable time (t
dis
with no external
load) indicates the delay between when OE
goes HIGH and when outputs actually
become disabled. The enable time (t
en
) indicates the amount of time the user must allow
for a one-shot circuitry to become operational after OE
is taken LOW. To ensure a
high-impedance OFF-state during power-up or power-down, pin OE
should be tied to
V
CC(A)
through a pull-up resistor. The minimum value of the resistor determines the
current-sourcing capability of the driver.
13.6 Pull-up or pull-down resistors on I/O lines
As mentioned previously, the NTB0101A is designed with low static drive strength to drive
capacitive loads of up to 70 pF. To avoid output contention issues, all pull-up or pull-down
resistors used, must be above 50 k. For this reason, NTB0101A is not recommended for
use in open-drain driver applications such as 1-Wire or I
2
C-bus. For these applications,
the NTS0101 level translator is recommended.
V
T
: input threshold voltage of the NTB0101A (typically V
CCI
/ 2).
V
D
: supply voltage of the external driver.
Fig 8. Typical input current versus input voltage graph
001aal922
V
T
/4 kΩ
−(V
D
− V
T
)/4 kΩ
I
I
V
I
