Rainbow Electronics MAX6510 - Manual (Page 4)

MAX6509/MAX6510
Resistor-Programmable
SOT Temperature Switches
4 _______________________________________________________________________________________
Pin Description
2 2 Ground GND
3 — Open-Drain Output. Reset to high impedance during power-on. OUT
— 3
Open-Drain with Internal Pull-Up Resistor, Active-High, or Active-Low Output.
See Table 1. Reset to deassert during power-on.
4 4 Hysteresis Selection. Hysteresis is 10°C for HYST = V CC , 2°C for HYST = GND. HYST
OUT,
OUT
5 6 Power-Supply Input
— 5
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.
OUTSET
V CC
1 1 SET Temperature Set Point. Connect an external 1% resistor from SET to GND to set trip point.
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 resistor
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 pre-
vents 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 temper-
ature (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).
Table 1. OUTSET-Selectable Outputs
PIN
FUNCTION
MAX6509 MAX6510
NAME
OUTSET OUT
Connected to V CC Active high
Connected to GND Active low
Unconnected
Open drain with internal
pull-up resistor