CC2540与CC2541的区别

如果 CC2540 上的 USB 未启用并且 CC2541 上的 I2C/ 额外 I/O 未启用，那么 CC2541 与 CC2540 在 6-mm x 6-mm 方形扁平无引脚 (QFN)40 封装内引脚兼容。 与 CC2540 相比，CC2541 提供更低 RF 流耗。 CC2541 没有 CC2540 所具有的 USB 接口，并在 TX 模式中提供较低的最大输出功率。 CC2541 还增加了 1 个 HW I2C 接口。

CC2541 与 CC2533 优化 RF4CE IEEE 802.15.4 SoC 引脚兼容。

TI Just released their new second Bluetooth Lower Energy single-mode SoC IC, the CC2541. ICs and EMKs, the modules that plug into the CC2540 Development Kit are now also available.

The CC2541 is similar to existing TI CC2540, but there are some differences:

Optimized TX power consumption. CC2541 draws 18.2 mA @ 0 dBm (14.3 mA when using TPS62730), compared to 27 mA @ 0 dBm for CC2540. Due to this optimization, maximum output power is 0 dBm for CC2541, compared with +4 dBm for CC2540. 
There is also a minor improvement in RX current; 17.9 mA versus 19.6 mA (14.7 mA versus 15.8 mA when using TPS62730).
The USB interface has been removed on CC2541. It has been replaced by a hardware I2C interface.
In addition to Bluetooth low energy/Bluetooth Smart, CC2541 supports proprietary radio communication at 2 Mbps, 1 Mbps, 500 kbps and 250 kbps. 
The CC2541 can be configured to be over-the-air compatible with CC2500/CC2510/CC2511 at 500 kbps and 250 kbps and with the 2.4 GHz RFICs from Nordic Semiconductor at 2 Mbps, 1 Mbps or 250 kbps the CC2540 only supported BLE.
As long as you don’t use USB or I2C, the CC2540 and CC2541 are 100% pin-compatible, including using the same values for the RF matching components, so it is easy to move back and forth between the two. 
On the software side, the modules are 100% compatible, as the BLE stack masks some minor differences in the radio interface. The latest version of the BLE stack has full support for both CC2540 and CC2541.
If you are unsure whether to use CC2540 or CC2541, here are some points to consider:

If you’re concerned with active power consumption, use CC2541, as it will save you 30% in TX and around 10% in RX.
If you need +4 dBm output power, you should choose the CC2540.
If you need a USB interface, you should choose the CC2540.
If you need I2C, you should choose the CC2541.
If you want to communicate using a proprietary protocol, you should choose the CC2541.
If none of the above apply, it doesn’t matter which one you choose. 
If cost is important, CC2541 is priced slightly lower than CC2540.