The HM-10 is rated to operate at a supply voltage of 2.0 to 3.7 volts, and its I/O are 3.3V tolerant!
HM-10, 11 and 12 all use TI’s BLE4.0 CC2540 chip. You can find more info here.
To put the device in sleep mode: send AT+SLEEP. To wake up from sleep mode, you can send a long string (>80 characters).
