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Small size
Description
The A1174 is a micro-power, Hall-effect latch for use in portable
devices that employ rotational detection systems, and have a
power supply voltage between 1.65 and 3.5 V. The device has
a single push-pull output structure and requires no external
pull-up resistor for reliable operation.
When a sufficient positive magnetic field is present on the
device, the device output transitions to the low state and is
latched in this state until a negative field of sufficient strength
latches the device output into the high state. The latched output
is ideal when using multiple sensors in rotational speed and
direction sensing systems (for example, track ball and scroll
bar systems in portable devices).
The device includes an innovative clocking scheme that
satisfies the micro-power needs of almost any application,
including track balls for PDAs and cell phones. Using the
EXTERNAL_CLK and DUAL_CLK pins as described in this
datasheet, the device can be set into various working modes.
In Dual Clock mode, the device switches between predefined
slow and fast sampling rates. The average current consumption
of the device is extremely low when rotation is not detected.
In External Clock mode, the user sets the clock rate for the
device to achieve the required on and off times for controlling
average power. This user-determined clocking also helps to
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Package: 6-contact MLP/DFN (suffix EW)
1.5 mm 脳 2 mm 脳 0.40 mm
Not to scale
+B
Magnetic Flux
Density
B
OP
0
B
RP
鈥揃
+V
B
OP
B
RP
B
OP
B
RP
A1174 Output
On
Off
On
Off
On
Figure 1. Timing diagram for output switching
A1174-DS
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