pi4uls5v104 Pericom Semiconductor Corporation, pi4uls5v104 Datasheet - Page 9

• Manufacturer Part Number: pi4uls5v104
• Description: 4-bit Bi-directional Level Shifter With Automatic Direction Controller
• Manufacturer: Pericom Semiconductor Corporation

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Principles of operation
Applications
The PI4ULS5V104 can be used in level-translation
applications for interfacing devices or systems operating at
different interface voltages with one another.
Architecture
The PI4ULS5V104 architecture(see Figure1) does not require
a direction-control signal to control the direction of data flow
from A to B or from B to A. In a dc state, the output drivers of
the PI4ULS5V104 can maintain a high or low, but are
designed to be weak, so that they can be overdriven by an
external driver when data on the bus starts flowing the
opposite direction.
The output one shots detect rising or falling edges on the A or
B ports. During a rising edge, the one shot turns on the PMOS
transistors (T1, T3) for a short duration, which speeds up the
low-to-high transition. Similarly, during a falling edge, the
one shot turns on the NMOS transistors (T2, T4) for a short
duration, which speeds up the high-to-low transition. The
typical output impedance during output transition is 70 Ω at
V
at V
Input Driver Requirements
Typical I
shown in Figure 2. For proper operation, the device driving
the data I/Os of the PI4ULS5V104 must have drive strength of
at least ±2mA.
CCO
CCO
=1.2 V to 1.8 V, 50 Ω at V
10-0011
=3.3 V to 5 V.
IN
vs V
IN
characteristics of the PI4ULS5V104 are
CCO
=1.8 V to 3.3 V, and 40 Ω
9
Power Up
During operation, ensure that V
power-up sequencing, VCCA ≥ VCCB does not damage the
device, so any power supply can be ramped up first. The
PI4ULS5V104 has circuitry that disables all output ports
when either V
Enable and Disable
The PI4ULS5V104 has an OE input that is used to disable the
device by setting OE = low, which places all I/Os in the high-
impedance (Hi-Z) state. The disable time (t
delay between when OE goes low and when the outputs
acutally get disabled (Hi-Z). The enable time (ten) indicates
the amount of time the user must allow for the one-shot
circuitry to become operational after OE is taken high.
Pull-up or Pull-down Resistors on I/O Lines
The PI4ULS5V104 is designed to drive capacitive loads of up
to 70 pF. The output drivers of the PI4ULS5V104 have low dc
drive strength. If pullup or pulldown resistors are connected
externally to the data I/Os, their values must be kept higher
than 50 kΩ to ensure that they do not contend with the output
drivers of the PI4ULS5V104.
For the same reason, the PI4ULS5V104 should not be used in
applications such as I
is connected on the bidirectional data I/O.
4-Bit Bi-directional Level Shifter with
Automatic Direction Controller
CC
is switched off (V
2
C or 1-Wire where an open-drain driver
PT0335-1
CCA
CCA/B
≤ V
CCB
PI4ULS5V104
= 0 V).
at all times. During
dis
) indicates the
07/06/10