SCEA147 September   2024 TXB0104 , TXB0302 , TXB0304

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2TXB-Type Architecture Differences
    1. 2.1 TXB0104 and TXB0304 Comparison
    2. 2.2 Recommended Device Selection
  6. 3Common Design Challenges
    1. 3.1 Distributed Load (Transmission Line Effect)
      1. 3.1.1 Cable Length Impact - Bench Findings
    2. 3.2 Impedance Matching
      1. 3.2.1 Bench Setup and Results
    3. 3.3 Lumped Load
  7. 4Case Study
  8. 5Summary
  9. 6References

2.1 TXB0104 and TXB0304 Comparison

Both device architectures share similar buffer loop structures that are always re-driving the I/Os through the internal series resistors by maintaining the current DC logic state. In the event of an AC state (rising/ falling edge), the one-shot circuitry is turned on to reduce the output impedance. This effectively drives the output to VCC (during a logic high) or GND (during a logic low), with a faster slew rate to achieve higher data rates. Table 2-1 depicts the differences in TXB010x and TXB030x.

Table 2-1 Specs Overview of TXB-Type Translators
Device
SpecTXB0104TXB0304
VCCA1.2V- 3.6V0.9V- 3.6V
VCCB1.65V- 5.5V0.9V- 3.6V
Power Supply RestrictionsVCCA≤ VCCB-
Internal Series Resistance4kΩ1kΩ
One-Shot Impedance (Typ.)

70Ω (VCCO= 1.2V- 1.8V)

50Ω (VCCO= 1.8V- 3.3V)

40Ω (VCCO= 3.3V-5V)

30Ω (VCCO= 0.9V- 1V)

10Ω (VCCO= 1.1V- 1.7V)

5Ω (VCCO= 1.8V-3.3V)

Max Data Rate100Mbps140Mbps
Input Driver RequirementsDrive Strength: ±2mADrive Strength: ±3mA