3-Wire Sinking Interface
Sinking outputs are often used in negative logic applications, where a low signal is required for an active state. Therefore, sinking outputs normally have current flowing into the device output lead when the device is active. Also called ìopen collector outputs,î sinking outputs are compatible with any logic family since a wide voltage range may be used for Vcc. Furthermore, the voltage level used to power the Hall effect assembly may differ from the pull-up resistor to which it is attached. The external pull-up resistor connected between the output and Vcc is required for proper operation. With the resistor connected as shown, the output will be îpulled upî to Vcc when off and (approximately) to ground when on.

Recommended pull-up resistor values are as follows:

3-Wire Sourcing Interface
Sourcing outputs are often used in positive logic applications, where a high signal is required for an active state. Thus, sourcing outputs normally have current flowing out of the device output lead when the device is active. Because a pull-down resistor is required for proper operation, sourcing outputs are compatible with CMOS logic, but not with TTL components. With the pull-down resistor connected as shown, the output will be ìpulled downî to ground when off and (approximately) to Vcc when on. 

Recommended pull-down resistor values are as follows:

2-Wire Current Sourcing Interface

Some applications require the sensor have only two connections. To accommodate these situations, several Cherry sensor assemblies are equipped with a 2-Wire interface (which may be tested as shown in the block diagram). When the sensor is idle, current flowing into the device via Pin1 and out via Pin 3 is limited to that needed to power the Hall effect device, a maximum of 6mA. When the sensor is active, the current flow will increase to a minimum of 10mA as the Hall effect device turns on the programmable current source. The voltage measured between the output and ground will therefore change by a minimum of 0.4 Vdc. If Pin 3 is connected to a comparator, the comparator output will switch in response to the change in voltage at Pin 3 of the sensor. Alternatively, Pin 3 can be connected directly to ground and a load placed between Pin 1 and Vcc. In this case, Pin 1 becomes the output lead to be connected to a comparator.