BU52001GUL_10 Datasheet, PDF (12/20 Pages) Rohm – Omnipolar Detection Hall ICs

BU52001GUL,BU52011HFV,BU52021HFV,
BU52015GUL,BU52025G,BU52051NVX, BD7411G
Technical Note
●Description of Operations
(Micropower Operation)
I_DD
Period
Startup time
Standby
Fig.34
The Omnipolar 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.
Reference period: 50ms (MAX100ms)
t
Reference startup time: 48μs
※BD7411G don’t adopts an intermittent operation method.
(Offset Cancelation)
V_DD
I
B_×
GND
Fig.35
＋
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. 35 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.
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12/19
2010.01 - Rev.C