Datasheet

Detailed Description
The MAX6509/MAX6510 fully integrated temperature
switches incorporate two temperature-dependent refer-
ences and one comparator. One reference exhibits a
positive temperature coefficient, and the other has a
negative temperature coefficient. 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
temperature is close to the threshold. The MAX6509
has an active-low, open-drain output structure that can
only sink current. The MAX6510 has three different out-
put options from which to choose (Table 1).
The MAX6509/MAX6510 are programmable for a wide
range of temperature thresholds from -40°C to +125°C.
The temperature threshold is set by an external resis-
tor between SET and GND. The MAX6509 output easily
interfaces with a microprocessor (µP) reset input
(Figure 2). The MAX6510 output is intended for applica-
tions such as driving a fan control switch (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 prevents
the output from oscillating when the temperature is near
the trip point. Do not leave HYST unconnected. Connect
HYST to GND or V
CC
. Other input voltages cause
increased supply current.
Choose the set-hot temperature (H) or set-cold tempera-
ture (C) option to ensure that the trip point is accurate
and the hysteresis is in the right direction. A MAX6509
or MAX6510 with the H suffix will first trip at the correct
point when temperature is increasing. For example, a
MAX6509HAUK+T or MAX6510HAUT+T with its trip
point set to 100°C will assert when its temperature rises
above +100°C, and will not deassert until its tempera-
ture drops below +100°C minus the selected hysteresis
value (e.g., +98°C if 2°C hysteresis is chosen). Con-
versely, if the trip temperature of a MAX6509CAUK+T
or MAX6510CAUT+T is -40°C, the output asserts at
-40°C as temperature falls, and deasserts when tem-
perature rises above -40°C plus the hysteresis value (e.g.,
-38°C if 2°C hysteresis is chosen) as shown in Figure 4.
Output Selection
The MAX6509 provides an open-drain output. The
MAX6510 features three output options selectable by
OUTSET (Table 1).
OUTSET OUT
Connected to VCC Active high
Connected to GND Active low
Unconnected
Open drain with internal
pull-up resistor
PIN
NAME FUNCTION
MAX6509 MAX6510
1 1 SET Temperature Set Point. Connect an external 1% resistor from SET to GND to set trip point.
2 2 GND Ground
3 — OUT Open-Drain Output. Reset to high impedance during power-on.
— 3
OUT,
OUT
Open-Drain with Internal Pull-Up Resistor, Active-High, or Active-Low Output.
See Table 1. Reset to deassert during power-on.
4 4 HYST Hysteresis Selection. Hysteresis is 10°C for HYST = V
CC
, 2°C for HYST = GND.
5 6 V
CC
Power-Supply Input
— 5 OUTSET
Trilevel Control Input:
OUTSET = V
CC
sets OUT to active high.
OUTSET = GND sets OUT to active low.
OUTSET = Unconnected sets OUT to open drain with internal pull-up resistor.
MAX6509/MAX6510 Resistor-Programmable
SOT Temperature Switches
www.maximintegrated.com
Maxim Integrated │ 4
Table 1. MAX6510 OUTSET-Selectable
Outputs
Pin Description