SC9201 Datasheet

Self-Adjusting Hall Effect Gear Tooth Sensor IC

The SC9201 is a sophisticated IC featuring an on-chip 10-bit A/D Converter and logic that act as a digital sample and hold circuit. A separate 4-bit D/A converter provides a fixed hysteresis. The SC9201 does not have a chopper delay and uses a single Hall plate which is immune to rotary alignment problems. The bias magnet can be from 100mT to 400mT. As the signal is sampled, the logic recognizes an increasing or decreasing flux density.

In the case of ferromagnetic toothed wheel application the IC has to be biased by the South pole of a permanent magnet (Maximum 400mT). When assembling the sensor system, a magnet as back bias flux from 100mT to 400mT is suggested. Normally the South pole of magnet faces the unbranded side of the IC and the magnet is glued to the back surface (non branded side) of the IC using an adhesive or suitable epoxy. Duo to the SC9201’s “Self-adjusting” over a wide range of back bias flux, the need for any trimming in the application is eliminated.

At the chip power on state, if the power is raised quickly and the output is reset to the high state whatever the field is. The output will change to low after the flux has reached its minimum value and then increased by an amount equal to the hysteresis. The output will change to high after the flux has reached its peak and then decreased by an amount equal to the hysteresis similarly. However if the supply is raised slowly, then the reset state is not determined; the output can be either high or low.

It is strongly recommended that an external ceramic bypass capacitor in the range 10nF to 1uF be connected between the supply and ground of the device to reduce external noise. The series resistor in combination with the bypass capacitor creates a filter for EMC pulse.

The pull-up resistor should be chosen to limit the current through the output transistor, without exceeding the maximum continuous output current of the device.

The device is available in a 3-pin SIP package and is lead (Pb) free, with 100% matte tin leadframe plating.