GND

Logic

Input

Output

VCC

Device

-IIK

+IIK

+IOK

-IOK

11

SN74HCS596-Q1

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SCLS805 – JUNE 2020

Product Folder Links: SN74HCS596-Q1

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Feature Description (continued)

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 VCC. 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.

8.3.3 CMOS Schmitt-Trigger Inputs

Standard CMOS inputs are high impedance and are typically modeled as a resistor in parallel with the input

capacitance given in the Electrical Characteristics. The worst case resistance is calculated with the maximum

input voltage, given in the Absolute Maximum Ratings, and the maximum input leakage current, given in the

Electrical Characteristics, using ohm's law (R = V ÷ I).

The Schmitt-trigger input architecture provides hysteresis as defined by ΔVT in the Electrical Characteristics,

which makes this device extremely tolerant to slow or noisy inputs. While the inputs can be driven much slower

than standard CMOS inputs, it is still recommended to properly terminate unused inputs. Driving the inputs slowly

will also increase dynamic current consumption of the device. For additional information regarding Schmitt-trigger

inputs, please see Understanding Schmitt Triggers.

8.3.4 Positive and Negative Clamping Diodes

The inputs and outputs to this device have both positive and negative clamping diodes as depicted in Figure 11.

CAUTION

Voltages beyond the values specified in the Absolute Maximum Ratings table can

cause damage to the device. The input negative-voltage and output voltage ratings

may be exceeded if the input and output clamp-current ratings are observed.

Figure 11. Electrical Placement of Clamping Diodes for Each Input and Output