An electronic assembly, comprising: an electronic device; a heat sink; a heat pump having thermal connections to the device and the heat sink and configured to transport heat from the device to the heat sink; a first temperature-responsive electrical element thermally coupled to the device, the first electrical element having a property that varies with temperature in a first direction; and a second temperature-responsive electrical element thermally coupled to the heat sink, the second electrical element having the same property as the first electrical element varying with temperature in a second direction opposite to the first direction; a control system configured to monitor a combined property of the first and second electrical elements in combination and characterized by the fact that the control system is configured to maintain the combined property at a substantially constant value by controlling current supplied to the heat pump, so that a temperature of the device varies dynamically in response to a temperature of the heat sink; wherein the property of the second electrical component is substantially constant with temperature below a threshold temperature so that, at heat sink temperatures below the threshold temperature, the control system operates to maintain the device at a substantially constant target temperature; and the property of the second electrical component varies with temperature above the threshold temperature so that, at heat sink temperatures above the threshold temperature, the control system operates to increase the target temperature of the device in line with the heat sink temperature. an electronic device; a heat sink; a heat pump having thermal connections to the device and the heat sink and configured to transport heat from the device to the heat sink; a first temperature-responsive electrical element thermally coupled to the device, the first electrical element having a property that varies with temperature in a first direction; and a second temperature-responsive electrical element thermally coupled to the heat sink, the second electrical element having the same property as the first electrical element varying with temperature in a second direction opposite to the first direction; a control system configured to monitor a combined property of the first and second electrical elements in combination and characterized by the fact that the control system is configured to maintain the combined property at a substantially constant value by controlling current supplied to the heat pump, so that a temperature of the device varies dynamically in response to a temperature of the heat sink; wherein the property of the second electrical component is substantially constant with temperature below a threshold temperature so that, at heat sink temperatures below the threshold temperature, the control system operates to maintain the device at a substantially constant target temperature; and the property of the second electrical component varies with temperature above the threshold temperature so that, at heat sink temperatures above the threshold temperature, the control system operates to increase the target temperature of the device in line with the heat sink temperature.