UM3308_16 Datasheet, PDF (9/13 Pages) Union Semiconductor, Inc. – 8-Bit Bidirectional Voltage-Level Translator with Auto Direction Sensing and ±15kV ESD Protection

UM3308/UM3308H
Input Driver Requirements
Typical I_IN vs V_IN characteristics of the UM3308/UM3308H are shown in Figure 2. For proper
operation, the device driving the data I/Os of the UM3308/UM3308H must have drive strength of
at least ±2mA.
I_IN
V_T/4kΩ
V_IN
-(V_D-V_T)/4kΩ
A: V_T is the input threshold voltage of the UM3308/UM3308H (typical V_CCI/2).
B: V_D is the supply voltage of the external driver.
Power Up
Figure 2 Typical I_IN vs. V_IN Curve
During operation, ensure that V_CCA≤V_CCB at all times. During power-up sequencing, V_CCA≥V_CCB
does not damage the device, so any power supply can be ramped up first. The
UM3308/UM3308H has circuitry that disables all output ports when either V_CC is switched off
(V_CCA/B=0 V).
Enable and Disable
The UM3308/UM3308H 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_dis) indicates the delay
between when OE goes low and when the outputs actually get disabled (Hi-Z). The enable time
(t_en) 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 UM3308/UM3308H is designed to drive capacitive loads of up to 50pF. The output drivers of
the UM3308/UM3308H have low dc drive strength. If pull-up or pull-down resistors are
connected externally to the data I/Os, their values must be kept higher than 50kΩ to ensure that
they do not contend with the output drivers of theUM3308/UM3308H.
For the same reason, the UM3308/UM3308H should not be used in applications such as I²C or
1-Wire where an open-drain driver is connected on the bidirectional data I/O.
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http://www.union-ic.com Rev.10 Mar.2016
9/13