4.2
ELECTRONICS OVERVIEW
Technical Service Manual
4 - 11
430-00587-008 (Rev. 2/05)
The lockout switch SW2 is located on the buzzer PWA and is accessible on the rear
enclosure of the Plum XLM. The lockout switch is connected to the LOCKOUT1 signal on
the display PWA, and to the LOCKOUT2 signal on the MCU PWA. LOCKOUT1 connects to
the collector of Q7 on the display PWA. When lockout switch SW2 is closed, and Q7
saturates, LOCKOUT2 goes low and the LOCKED icon on the LCD illuminates.
The display PWA receives serial data from the MCU PWA and displays it at the LCD
Figure 9-18, Display PWA Schematic (XL)
Figure 9-19, Display PWA Schematic (XLM))
The display PWA also includes most of the control knob functions required to operate the
infusion system. The display PWA includes the following circuitry: display,
electroluminescent (EL) panel driver (XL), LED backlight panel and driver (XLM), RUN
indicator, line power indicator, and control knob.
ICs U2 and U3 are master- and slave-type serial input LCD drivers and are cascaded to
form a 92-segment (4 back-plane by 23 fore-plane) driver. LCD panel U1 is designed to
match the drivers and has 88 segments.
Display data is serially clocked into U2 at pin 21. The clocking signal, LCD CLK, is received
at U2-23 and U3-22. The drive frequency is not synchronized to the data input and is
dictated by resistor R7. To eliminate a false display during data updates, U2 and U3 are
disabled by CR3, C14, R9, R8, and Q3.
DISPLAY CIRCUITRY (XLM DISPLAY PWA -003 AND LOWER)
IC U2 is the 128 segment LCD driver that can drive the four backplanes and 32 frontplanes.
LCD panel U4 has 110 front panel segments multiplexed with the four backplanes.
Display data is clocked serially into U2 via DIN (pin 39) and DCLK (pin 38). The LCD drive
frequency (approximately 100 Hz) is set by R7 and is not synchronized to the data input
into U2.
DISPLAY CIRCUITRY (XLM DISPLAY PWA -004 AND HIGHER)
IC U13 is the 128 segment LCD driver that can drive the four backplanes and 32
frontplanes. LCD panel U4 has 110 front panel segments multiplexed with the four
backplanes.
Display data is clocked serially into U13 via DATA (pin 58) and SCL (pin 57). The LCD
drive frequency (approximately 100 Hz) is set by R31 and is not synchronized to the data
input into U13.
Summary of Contents for LifeCare XL Series
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