JEDEC – no definition offered

TI – The current flowing into a 3-state output with input conditions established that, according to the product specification, will establish the high-impedance state at the output with a high-level voltage applied to the output.

This parameter is measured with other input conditions established that would cause the output to be at a low level if it were enabled. IOZH is tested by applying the specified voltage to the output and measuring the current into the device with the output in the high-impedance state.

Input conditions that would establish a low level on the output if it were enabled are VIL = VIL max and VIH = VIH min. Each output is tested individually. For example, the unused inputs are at VIL = 0 or VIH = VCC for AC devices and VIL = 0 or VIH = 3 V for ACT devices, depending on the desired state of the outputs not being tested.

An IOZH specification on I/O devices with bus hold on the data input/output pins, with a test condition of VO >> VCC, indicates that the overvoltage-tolerant bus-hold output has a Schottky blocking diode in series with the output p-channel pullup transistor to VCC. This diode prevents current flowing from the output back into the VCC supply. See II(hold) and Ioff for more information.