MC33794 Просмотр технического описания (PDF) - Motorola => Freescale
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MC33794 Datasheet PDF : 20 Pages
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SOICW-EP PIN FUNCTION DESCRIPTION (continued)
Pin
Pin Name
Formal Name
Definition
36 – 44
E1 – E9
Electrode Connections
These are the electrode pins. They are connected either directly or through coaxial
cables to the electrodes for measurements. One of these electrodes can be selected
at a time for capacitance measurement. All of the other unselected electrodes are
grounded by an internal switch. The signal at the selected electrode pin is routed to
the shield driver amplifier by an internal switch. All of the coaxial cable shields should
be isolated from ground and connected SHIELD.
45, 46
REF_A,
REF_B
Reference Connections
These pins can be individually selected like E1 through E9. Unlike E1 through E9,
these pins are not grounded when not selected. The purpose of these pins is to allow
known capacitors to be measured. By using capacitors at the low and high end of the
expected range, absolute values for the capacitance on the electrodes can be
computed.
47
ISO_OUT
ISO-9141 Output
This pin translates ISO-9141 receive levels to 5.0 V logic levels for the MCU.
51
ISO_IN
ISO-9141 Input
This pin accepts data from the MCU to be sent over the ISO-9141 communications
interface. It translates the 5.0 V logic levels from the MCU to transmit levels on the
ISO-9141 bus.
53
ISO-9141
ISO-9141 Bus
This pin connects to the ISO-9141 bus. It provides the drive and detects signaling on
the bus and translates it from the bus level to logic levels for the MCU.
54
LAMP_OUT
Lamp Driver
This is an active low output capable of sinking current of a typical indicator lamp. One
end of the lamp should be connected to a positive supply (for example, battery
voltage) and the other side to this pin. The current is limited to prevent damage to the
IC in the case of a short or surge during lamp turn-on or burn-out.
33794
8
MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA
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