Hospira LifeCare XL Series, Technical & Service Manual

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4.2 ELECTRONICS OVERVIEW
Technical Service Manual 4 - 9 430-00587-008 (Rev. 2/05)
4.2.3.6
MOTOR DRIVER CIRCUITRY
The motor driver circuitry energizes the three stepper motors: plunger, input/output, and
primary/secondary. The MCU PWA micro controller, U6, outputs MOTPHAS1 and
MOTPHAS2 to inverters U9A and U9F which generate two additional signals: *MOTPHAS1
and *MOTPHAS2. These four signals are required to step the motors. Three motor enable
signals manage the motor step width. The motor enable signals are: MOTPLN_EN (motor
plunger enable), MOTIO_EN (motor input/output enable), and MOTPS_EN (motor
primary/secondary enable). The four motor stepping signals activate ICs U2A, U3A, U3D,
and U2D; or U2B, U3B, U3C, and U2C; or U5D, U5A, U4A, and U4D to switch the power
metal-oxide semiconductor field-effect transistors (MOSFETs) Q1 through Q4, Q5 through
Q8, or Q9 through Q12. When active, *RESET disables motor activity.
4.2.3.7
PIN DETECTOR CIRCUITRY
The pin detector circuitry detects the primary and secondary valve pin motion. When
PSV_EN is active, *PSV_EN becomes active and a constant current flows through
light-emitting diode (LED) CR1 and LED CR2. CR1 and CR2 are located in the pin detector
sensor assembly mounted on the bubble sensor PWA. If *P_S_EN is active, IC U11A is
activated and U11B is de-activated, and vice versa. U11 serves as two hysteresis
comparators and its output, PS_VALVE, is edge detected by the MCU PWA. The positive
edges are detected by the MCU PWA INT1 input. The negative edges are detected by the
MCU PWA PC3 input.
4.2.3.8
UART (XLM WITH DATAPORT)
The UART used in the Plum XLM with DataPort infusion system is TL16C450 made by
Texas Instruments. It is a complementary metal-oxide semiconductor (CMOS) field-effect
transistor (FET) version of an asynchronous communication element (ACE) typically
functioning in a microcomputer system as a serial input/output interface.
The UART performs serial-to-parallel conversion on data received from the host computer
and performs parallel-to-serial conversion on data received from the MCU. The MCU can
read the status of the UART at any point in its operation. The status information includes
the type of transfer operation in progress, the status of the operation, and any error
conditions encountered.
The UART includes a programmable, on-board baud rate generator which is capable of
dividing a reference clock input by divisors from 1 to (216 -1) and producing a 16 x clock
to drive the internal transmitter logic. Provisions are also included to use this 16 x clock
to drive the receiver logic. In the Plum XLM with DataPort infusion system, data is
transmitted and received at 1,200 bits per second. The 16 x clock is running at 19,200
Hz (16 x 1,200).