Preliminary Specification
© Andigilog, Inc. 2006
www.andigilog.com
August 2006 - 70A04018
aMC8500
- 13 -
When powering an unbuffered Hall sensor from motor voltage VM,
resistor R1 is required. This resistor sets the Hall operating current
and places the output within the input common mode voltage range
of the Hall Amplifier.
Unbuffered Hall sensors that require less than 10 mA can be
powered directly from the Reference output thus eliminating the
need for bias resistor R1. This bias method will disable the
automatic power down feature if the sensors require more than
2.0 mA.
The Op Amp output can be used as alternative method for powering
unbuffered Hall sensors that require less than 10 mA. This method
eliminates the need for bias resistor R1 while also preserving the
automatic power down feature. With this bias method the reference
output is essentially unloaded.
Pull-up resistor R1 is required when using buffered Hall sensors that
have an open collector output. Resistors R2 and R3 bias the unused
amplifier input to a level that is within its input common mode range.
Resistor R1 is required for buffered Hall sensors with an open
collector output. Resistors R2 and R3 can be eliminated by biasing
the unused amplifier input from the reference.
Figure 20- Motor Supply Powered Unbuffered Hall
Figure 22- Op Amp Powered Unbuffered Hall
Figure 24- Reference Biased Buffered Hall
With the addition of an economical PNP transistor, the Reference
output current can be boosted above 100 mA. This simple buffer
circuit will not have the benefit of maintaining short circuit protection.
Asahi Kasei
HW-101A
R1
H
VDD
Under Voltage
Lockout
Hall Amplifier
Non-Overlap
Commutation
12
VM
3
4
H
VDD
Under Voltage
Lockout
Hall Amplifier
Non-Overlap
Commutation
12
VM
3
4
Toshiba
TSH124
Reference
9
8
7
5
Op Amp
VM
VDD
Under Voltage
Lockout
Hall Amplifier
Non-Overlap
Commutation
12
3
4
Reference
5
Ana Chip
ATS177
R1
H
Figure 21- Reference Powered Unbuffered Hall
VM
H
VDD
Under Voltage
Lockout
Hall Amplifier
Non-Overlap
Commutation
12
3
4
Toshiba
TSH124
Reference
5
Figure 23- Motor Supply Biased Buffered Hall
Ana Chip
ATS177
R1
H
VDD
Under Voltage
Lockout
Hall Amplifier
Non-Overlap
Commutation
12
VM
3
4
R2
R3
Figure 25- Reference Buffer
5
VM
VDD
Under Voltage
Lockout
12
Reference
100
KEC
KTA1270
Load
0.1
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