ZHCSN18B September 2020 – February 2022 SN74HCS245-Q1
PRODUCTION DATA
- 1 特性
- 2 应用
- 3 说明
- 4 Revision History
- 5 Pin Configuration and Functions
- 6 Specifications
- 7 Parameter Measurement Information
- 8 Detailed Description
- 9 Application and Implementation
- 10Power Supply Recommendations
- 11Layout
- 12Device and Documentation Support
- 13Mechanical, Packaging, and Orderable Information
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散热焊盘机械数据 (封装 | 引脚)
- RKS|20
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8.3.1 CMOS IOs
This device includes CMOS IOs. These pins can be configured as either an input or an output. The output has the balanced 3-state architecture, and the input has the Schmitt-trigger architecture.
The three states that these outputs can be in are driving high, driving low, and high impedance. The term "balanced" indicates that the device can sink and source similar currents. The drive capability of this device may create 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 output power of the device to be limited to avoid damage due to overcurrent. The electrical and thermal limits defined in the Absolute Maximum Ratings must be followed at all times.
When the pin is configured as an input, the output is placed into a high-impedance state and it will neither source nor sink current, with the exception of minor leakage current as defined in the Electrical Characteristics table. In the high-impedance state, the output voltage is not controlled by the device and is dependent on external factors. If no other drivers are connected to the node, then this is known as a floating node and the voltage is unknown. Because this pin also includes an input, the voltage should always be defined.
The Schmitt-trigger input architecture provides hysteresis as defined by ΔVT in the Electrical Characteristics table, 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 with slow transitioning signals will increase dynamic current consumption of the device. For additional information regarding Schmitt-trigger inputs, please see Understanding Schmitt Triggers.
Unused transceiver channels should be terminated as shown in Figure 8-2.
Figure 8-2 Proper termination of unused transceiver channels