The MAX1978/MAX1979 are the smallest, safest, most accurate complete single-chip temperature controllers for Peltier thermoelectric cooler (TEC) modules. On-chip power FETs and thermal control-loop circuitry minimize external components while maintaining high efficiency. Selectable 500kHz/1MHz switching frequency and a unique ripple-cancellation scheme optimize component size and efficiency while reducing noise. Switching speeds of internal MOSFETs are optimized to reduce noise and EMI. An ultralow-drift chopper amplifier maintains 0.001C temperature stability. Output current, rather than voltage, is directly controlled to eliminate current surges. Individual heating and cooling current and voltage limits provide the highest level of TEC protection.