Datasheet
MAX6501–MAX6504
Low-Cost, +2.7V to +5.5V, Micropower
Temperature Switches in SOT23
4 _______________________________________________________________________________________
Pin Description
1, 2 1, 2
Ground. Not internally connected. Connect both ground pins
together close to the chip. Pin 2 provides the lowest thermal
resistance to the die.
1, 2
PIN
1, 2 GND
3 3
Hysteresis Input. Connect HYST to GND for 2°C hysteresis, or
connect to V
CC
for 10°C hysteresis.
3 3 HYST
4 4 Supply Input (+2.7V to +5.5V)
5 —
Open-Drain, Active-Low Output. TOVER goes low when the die
temperature exceeds the factory-programmed temperature
threshold. Connect to a 100kΩ pullup resistor. May be pulled
up to a voltage higher than V
CC
.
— —
TOVER
4 4 V
CC
— 5
Push-Pull Active-High Output. TOVER goes high when the die tem-
perature exceeds the factory-programmed temperature threshold.
— —
Open-Drain, Active-Low Output. TUNDER goes low when the
die temperature goes below the factory-programmed tempera-
ture threshold. Connect to a 100kΩ pullup resistor. May be
pulled up to a voltage higher than V
CC
.
5 —
TUNDER
— —
Push-Pull Active-High Output. TUNDER goes high when the die tem-
perature falls below the factory-programmed temperature threshold.
— 5 TUNDER
— — TOVER
MAX6502MAX6501 MAX6503 MAX6504
NAME FUNCTION
________________General Description
The MAX6501–MAX6504 fully integrated temperature
switches incorporate two temperature-dependent refer-
ences and a comparator. One reference exhibits a pos-
itive temperature coefficient and the other a negative
temperature coefficient (Figure 1). The temperature at
which the two reference voltages are equal determines
the temperature trip point. Pin-selectable 2°C or 10°C
hysteresis keeps the output from oscillating when the
die temperature approaches the threshold temperature.
The MAX6501/MAX6503 have an active-low, open-
drain output structure that can only sink current. The
MAX6502/MAX6504 have an active-high, push-pull out-
put structure that can sink or source current. The inter-
nal power-on reset circuit guarantees the output is at
T
TH
= +25°C state at startup for 50µs.
The MAX6501–MAX6504 are available with factory-
preset temperature thresholds from -45°C to +125°C in
10°C increments. Table 1 lists the available temperature
threshold ranges. The MAX6501/MAX6503 outputs are
intended to interface with a microprocessor (µP) reset
input (Figure 2). The MAX6502/MAX6504 outputs are
intended for applications such as driving a fan control
(Figure 3).
Hysteresis Input
The HYST pin is a CMOS-compatible input that selects
hysteresis at either a high level (10°C for HYST = V
CC
)
or a low level (2°C for HYST = GND). Hysteresis pre-
vents the output from oscillating when the temperature
approaches the trip point. The HYST pin should not be
left unconnected. Drive HYST close to ground or V
CC
.
Other input voltages cause increased supply current.
The actual amount of hysteresis depends on the part’s
programmed trip threshold (see the
Typical Operating
Characteristics
).
Table 1. Factory-Programmed Threshold
Range
+35°C < T
TH
< +125°C
+35°C < T
TH
< +125°C
THRESHOLD (T
TH
) RANGE
-45°C < T
TH
< +15°C
-45°C < T
TH
< +15°C
MAX6503
MAX6504
MAX6501
MAX6502
PART