Motorola T200 Service Manual page 66

Topaz T2688/T200, T2988/T205 L3 Circuit Description
Display
95. The LCD module is a 98 X 64, Chip on Glass device and measures 37 x 33mm with a
polyamide foil connection to the PCB through U24. Support for the LCD is through
DVCC.
96. Contrast control is achieved by the variation in voltages, which are stored in
through C44 and DC / DC LCD driving voltages provided by
97. Data to and from the LCD is though the data bus
98. Chip select is sent from
connector on Pin 27.
Vibrator and Alert
99. The vibrator is driven by the signal
signal is applied to the base of
second transistor to conduct forcing the collector high. This then effectively give s the
vibrator support voltage
100. U6 provide EMF protection.
101. The buzzer / alert is operated, using the signal
this signal forces
voltage VBAT to earth.
102. U7 Provides EMF protection for the buzzer.
Keypad and Back lights
103. The backlights are split into 3 for the LCD
of which there are 8
LEDON (This is generated from
signal B L from Gemini
support voltage VBAT
104. The keypad is made up of a 4 column x 5 Row matrix, with the
ROW 0 being generated from
signals, COL3 Gemini
105. The 2 signals
detect switch U34
15
Gemini Pin 48 to
AAGC
Dual NPN / PnP transistor
VBAT a path to earth through
BQ4 to conduct creating the current path for the
(D4 – D11). The backlights are switched on using the signal
Keypad detect switch U34
Pin 134. LEDON
to illuminate the backlights.
Gemini
Pin 129, COL2
ROW4 and COL4 are used as outputs from the
to inform the unit to switch on during sleep mode.
Motorola Proprietary Information
D0 – D7, U24
LCD Connector Pin 28, with the
which originates from
U44, this then causes the
BQ1
BUZZER
(D1 – D3) and the keypad backlights
then forces BQ2
Pins 126 to Pins 122 respectively. The column
Pin 128, COL1 Pin 133 &
C40
C45 through C48.
Pins 16 – 24
Reset
VEGA Pin 45, this
from Gemini Pin 20,
buzzer U8 support
and is switched by the
to conduct allowing the
signals ROW4 –
COL0 Pin 132.
Gemini to Keypad
on