8.3.2 CMOS Open-Drain Outputs

The open-drain output allows the device to sink current to GND but not to source current from V_CC. When the output is not actively pulling the line low, it will go into a high impedance state. This allows the device to be used for a wide variety of applications, including up-translation and down-translation, as the output voltage can be determined by an external pull-up resistor.

The current drive capability of this device creates fast edges into light loads, so routing and load conditions should be considered to prevent ringing. Additionally, the outputs of this device are capable of driving larger currents than the device can sustain without being damaged. It is important for the power output of the device to be limited to avoid thermal runaway and damage due to over-current. The electrical and thermal limits defined the in the Absolute Maximum Ratingsmust be followed at all times.

The SN74HCS596-Q1 can drive a load with a total capacitance less than or equal to the maximum load listed in the Switching Characteristics connected to a high-impedance CMOS input while still meeting all of the datasheet specifications. Larger capacitive loads can be applied, however it is not recommended to exceed the provided load value. If larger capacitive loads are required, it is recommended to add a series resistor between the output and the capacitor to limit output current to the values given in the Absolute Maximum Ratings.