A temperature sensor includes a counting signal generation unit, a counting signal decoding unit, an input reference voltage selection unit, and a latch pulse generation unit. The counting signal generation unit is configured to generate one or more counting signals in response to an oscillation signal. The counting signal decoding unit is configured to decode the one or more counting signals and to generate one or more test selection signals and an end signal. The input reference voltage selection unit is configured to output a first selection reference voltage or a second selection reference voltage as an input reference voltage in response to the one or more test selection signals. The latch pulse generation unit is configured to generate one or more latch pulses in response to the one or more test selection signals.