用TI的MAX3232芯片的2个小板各自的两路232转TTL都能使用,完全正常

用美信的MAX3232的2个小板,一个板完全不能工作.另一个板,1路的发送能用,接收不能用,2路的接收能用,发送不能用,也就是组合起来有一路可用.

估计是在通信速率上的差异吧
MAXIM产的MAX3232：速率上限是120kbps
TI产的MAX3232：速率上限是250kbps

3V 至 5.5V 多通道 RS-232 线路驱动器/接收器

说明The MAX3232 device consists of two line drivers, two line receivers, and a dual charge-pump circuit with ±15-kV ESD protection pin to pin (serial-port connection pins, including GND). The device meets the requirements of TIA/EIA-232-F and provides the electrical interface between an asynchronous communication controller and the serial-port connector. The charge pump and four small external capacitors allow operation from a single 3-V to 5.5-V supply. The devices operate at data signaling rates up to 250 kbit/s and a maximum of 30-V/µs driver output slew rate.


特性

• RS-232 Bus-Pin ESD Protection Exceeds ±15 kV Using Human-Body Model (HBM)
• Meets or Exceeds the Requirements of TIA/EIA-232-F and ITU v.28 Standards
• Operates With 3-V to 5.5-V VCC Supply
• Operates up to 250 kbit/s
• Two Drivers and Two Receivers
• Low Supply Current... 300 µA Typical
• External Capacitors... 4 × 0.1 µF
• Accepts 5-V Logic Input With 3.3-V Supply
• Alternative High-Speed Pin-Compatible Device (1 Mbit/s)
  • SNx5C3232
• Applications
  • Battery-Powered Systems, PDAs, Notebooks, Laptops, Palmtop PCs, and Hand-Held Equipment