DS56 Datasheet, PDF (3/6 Pages) Dallas Semiconductor – Dual Temperature Comparator

DS56
OVERVIEW
A block diagram of the DS56 is shown in Figure 1. The DS56 consists of three major components:
1. Precision bandgap voltage reference
2. Temperature sensor
3. Thermostat comparators
The DS56 incorporates an internal temperature sensor with a typical transfer function of (in mV with T
expressed in °C):
V_TEMP (T) = 6.2 T + 395
The voltage associated with this transfer function is output on the V_TEMP pin, which has a typical output
impedance of 1.5 kΩ .
The DS56 has two independent temperature comparators, each with its own input (or trip point) and
output. The comparison voltage (the V_TEMP transfer function) is the same for both comparators.
Additionally, the hysteresis for both comparators is typically 5°C (31.0 mV).
The DS56 bandgap voltage reference is available on pin 1 to allow for a designer to set the trip point(s)
by resistively dividing the reference voltage. One possible scenario is illustrated in Figure 1. For optimum
performance, the VREF pin should be connected to a 50 µA load.
The comparator outputs are taken off-chip via open-drain FETs, thus requiring external pullups. The
thermostat transfer function is illustrated in Figure 2.
The supply range of the DS56 is 2.7V to 5.5V, allowing for applications ranging from industrial control
to battery-powered portable equipment.
THERMOSTAT OUTPUT TRANSFER FUNCTION Figure 2
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