SLLA660 December 2024 THVD1400 , THVD2410
- 1
- Abstract
- Trademarks
- 1 Introduction
- 2 Overview of RS-485
- 3 Shorting DE and nRE Pins
- 4 General R Pin Glitch Background
- 5 Theoretical Glitch Case for RS-485 Transceivers
- 6 Theoretical THVD24XX Idle Fail-safe Case
- 7 RS-485 Testing Setup
- 8 THVD1400 Capacitance Results
- 9 THVD2410 Capacitance Results
- 10Voltage Drop Workarounds
- 11Summary
- 12References
9 THVD2410 Capacitance Results
With an identical setup to the THVD1400, THVD2410 shows that idle fail-safe is triggered across every capacitance test. When switching from transmit to receive modes, THVD2410 enters the idle fail-safe for 10 µs.Figure 9-1and Figure 9-2 both show the same fail-safe time of 10 µs at 50pF and 1000pF. These results are consistent across singled-ended and differential capacitances.
Figure 9-1 THVD2410 50pF Single-ended Capacitance
Figure 9-2 THVD2410 1000pF Single-ended CapacitanceSince the bus differential voltage enters the VTH_FSH range for a long enough period of time, THVD2410 enters the idle fail-safe mode.
Table 9-1 THVD2410 Fail-safe Results
| Capacitance | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| 50pF | 100pF | 220pF | 330pF | 470pF | 570pF | 760pF | 860pF | 1000pF | |
| Single-ended Glitch Time (µs) | 10.56 | 10.67 | 10.63 | 10.69 | 10.65 | 10.71 | 10.63 | 10.65 | 10.69 |
| Single-ended Voltage Drop (V) | 0.60 | 0.69 | 0.65 | 0.64 | 0.73 | 0.65 | 0.48 | 0.61 | 0.64 |
| Differential Glitch Time (µs) | 10.67 | 10.76 | 10.71 | 10.65 | 10.67 | 10.71 | 10.67 | 10.68 | 10.77 |
| Differential Voltage Drop (V) | 0.56 | 0.73 | 0.72 | 0.63 | 0.68 | 0.56 | 0.69 | 0.77 | 0.65 |