voh

VOH stands for output high voltage. In digital electronics, VOH is the voltage level that a logic output presents when it is driving a high (logic “1”). It is a key parameter in ensuring that a signal is recognized as high by receiving inputs.

VOH is specified as VOH(min) under a defined output current, typically denoted IOH, which is the current the device must be able to source while maintaining the high level. Some datasheets also provide VOH(max) for particular conditions, but the important spec for compatibility is usually VOH(min) at a given IOH. The exact numbers depend on the integrated circuit family, supply voltage, and environmental conditions.

The value of VOH depends on several factors, including the supply voltage (Vcc), temperature, and the load on the output. As the device sources more current, voltage drops occur due to the finite output resistance of the driver, so VOH may decrease with heavier loading. Consequently, designers compare VOH with the input high threshold (VIH) of the following stage to ensure reliable interpretation of a high level. VOH is typically considered alongside VOL (output low voltage) and the output or input current ratings (IOH, IOL) in determining noise margins and system reliability.

In practice, VOH is documented in data sheets for logic families such as TTL and CMOS, and is used to guarantee compatibility between driving and receiving circuits. It is one of several interrelated parameters used to characterize digital signaling and ensure correct logic operation across varying operating conditions.