The TXB010x parts will go down low enough:
1.2 V to 3.6 V on A Port and 1.65 V to 5.5 V on B Port (VCCA ? VCCB)
So will the Atmel AVR ISP MKii:
"•Programs both flash and EEPROM
•Supports fuses and lock bit programming
•Upgradeable for future device support
•Supports target voltages from 1.8V to 5.5V
•Adjustable ISP programming speed (50Hz to 8MHz SCK frequency)
•USB 2.0 compliant (full speed, 12Mbps)
•Powered from USB, does not require external power supply
•Target interface protection
•Short-circuit protection"
txb0104.pdf (1.15 MB)