General Description
ATS276/277 are integrated Hall sensors with output drivers, mainly designed for electronic commutation of brush-less DC Fan. This IC internally includes the regulator, protecting diode, Hall plate, amplifier, comparator, and a pair of complementary open-collector outputs (DO, DOB).
While the magnetic flux density (B) is larger than operate point (Bop), DO will turn on (low), and meanwhile DOB will turn off (high). Each output is latched until B is lower than release point (Brp), and then DO、DOB transfer each state.
For DC fan application, sometimes need to test power reverse connection condition. Internal diode only protects chip-side but not for coil-side. If necessary, add one external diode to block the reverse current from coil-side.

Features
*On-chip Hall sensor with two different sensitivity and hysteresis settings for ATS276/277
*3.5V to 20V operating voltage
*400mA (avg) output sink current
*Build-in protecting diode only for chip reverse power connecting
*-20°C to 85°C operating temperature
*Low profile 4 pin SIP package

Applications
*Dual-coil Brush-less DC Motor
*Dual-coil Brush-less DC Fan
*Revolution Counting
*Speed Measurement

ATS277, ATS276A-PLA-A, ATS277A-PLA-A, ATS276B-PLA-A, ATS277B-PLA-A

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General Description
The DM74121 is a monostable multivibrator featuring both positive and negative edge triggering with complementary outputs. An internal 2kΩ timing resistor is provided for design convenience minimizing component count and layout problems. this device can be used with a single external capacitor. Inputs (A) are active-LOW trigger transition inputs and input (B) is and active-HIGH transition Schmitttrigger input that allows jitter-free triggering from inputs with
transition rates as slow as 1 volt/second.
A high immunity to VCC noise of typically 1.5V is also provided by internal circuitry at the input stage. To obtain optimum and trouble free operation please read operating rules and one-shot application notes carefully and observe recommendations.

Features
* Triggered from active-HIGH transition or active-LOW transition inputs
* Variable pulse width from 30 ns to 28 seconds
* Jitter free Schmitt-trigger input
* Excellent noise immunity typically 1.2V
* Stable pulse width up to 90% duty cycle
* TTL, DTL compatible
* Compensated for VCC and temperature variations
* Input clamp diodes

DM74121N

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