UM3308_16 Datasheet, PDF (8/13 Pages) Union Semiconductor, Inc. – 8-Bit Bidirectional Voltage-Level Translator with Auto Direction Sensing and ±15kV ESD Protection

UM3308/UM3308H
Applications Information
UM3308/UM3308H ESD protected level translator provides level shifting necessary to allow data
transfer in a multi-voltage system. Externally applied voltages, V_CCA and V_CCB set the logic levels
on either side of device. A low voltage signal present on V_CCA side of the device appears as a high
voltage logic signal on the V_CCB side of the device, and vice-versa.
Block Diagram
The UM3308/UM3308H (block diagram see Figure 1) 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 UM3308/UM3308H 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 to the opposite direction.
The output one shot detects 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.
VCCA
VCCB
I/O A
P
One Shot
T3
4K
T4
N
One Shot
P
One Shot
T1
4K
N
One Shot
T2
I/O B
Figure 1 Block Diagram of UM3308/UM3308H I/O Cell
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http://www.union-ic.com Rev.10 Mar.2016
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