BU52002GUL_10 Datasheet, PDF (8/14 Pages) Rohm – Unipolar Detection Hall ICs

BU52002GUL,BU52003GUL,BU52012HFV,BU52013HFV
Technical Note
●Description of Operations
(Micropower Operation)
IDD
Period
Startup time
Standby
The unipolar detection Hall IC adopts an intermittent
operation method to save energy. At startup, the Hall
elements, amp, comparator and other detection circuits
power ON and magnetic detection begins. During standby,
the detection circuits power OFF, thereby reducing current
consumption. The detection results are held while standby
is active, and then output.
Fig.32
(Offset Cancelation)
V_DD
I
B_×
GND
Fig.33
t
Reference period: 50ms (MAX100ms)
Reference startup time: 24μs
＋
Hall Voltage
－
The Hall elements form an equivalent Wheatstone (resistor)
bridge circuit. Offset voltage may be generated by a
differential in this bridge resistance, or can arise from changes
in resistance due to package or bonding stress. A dynamic
offset cancellation circuit is employed to cancel this offset
voltage.
When Hall elements are connected as shown in Fig. 33 and a
magnetic field is applied perpendicular to the Hall elements,
voltage is generated at the mid-point terminal of the bridge.
This is known as Hall voltage.
Dynamic cancellation switches the wiring (shown in the figure)
to redirect the current flow to a 90˚ angle from its original path,
and thereby cancels the Hall voltage.
The magnetic signal (only) is maintained in the sample/hold
circuit during the offset cancellation process and then
released.
(Magnetic Field Detection Mechanism)
S
N
S
S
N
S
N
Flux
Flux
Fig.34
The Hall IC cannot detect magnetic fields that run horizontal to the package top layer.
Be certain to configure the Hall IC so that the magnetic field is perpendicular to the top layer.
www.rohm.com
© 2010 ROHM Co., Ltd. All rights reserved.
8/13
2010.01 - Rev.B