Diodes AH278 - Manual

HIGH VOLTAGE HALL EFFECT LATCH AH278
1
Nov. 2009 Rev. 1. 4 BCD Semiconductor Manufacturing Limited
Data Sheet
General Description
The AH278 is an integrated Hall sensor with output
driver designed for electronic commutation of brush-
less DC motor applications. The device includes an on-
chip Hall sensor for magnetic sensing, an amplifier
that amplifies the Hall voltage, a Schmitt trigger to
provide switching hysteresis for noise rejection and
two complementary open-collector drivers for sinking
large load current. It also includes an internal band-gap
regulator which is used to provide bias voltage for
internal circuits and allows a wide operating supply
voltage ranges.
Placing the device in a variable magnetic field, if the
magnetic flux density is larger than threshold B
OP
, the
pin DO will be turned low (on) and pin DOB will be
turned high (off). This output state is held until the
magnetic flux density reverses and falls below B
RP,
then causes DO to be turned high (off) and DOB
turned low (on).
AH278 is available in TO-94 (SIP-4L) package.
Features
· On-Chip Hall Sensor
· 4V to 30V Supply Voltage
· 500mA (avg) Output Sink Current
· Build in Protection Diode for Reverse Power
Connecting
· -20 o C to 85 o C Operating Temperature
· Low Profile TO-94 (SIP-4L) Package
· Build in Over Temperature Protection Function
· ESD Rating: 300V(Machine Model)
Applications
· 12V/24V Dual-Coil Brushless DC Motor/Fan
· Power Supply and Switchboard
· Communications Facilities
· Industrial Equipment
Figure 1. Package Type of AH278
TO-94