Display Backlights; 32Khz Rtc; Sim Card Circuit - Motorola W208 Manual

W208 Level 3 Circuit Description
Figure 14: The pin connections of TFT LCD and U101 Locosto-Plus

7.1 Display Backlights

The Display backlights are provided by the control signal LEDLCM_EN Locosto-Plus Pin
A5. After LEDLCM_EN Locosto-Plus Pin A5 control signal turned on, Charge Pump U701
will charge the flying capacitor (C702) to supply 5V for two shunt LEDs in LCM. On another
side, when LEDLCM_EN Locosto-Plus Pin B11 control signal is high, the keypad light will
be turned on.

8 32kHz RTC

The Real-time Clock Interface is part of the Triton-Lite U103 in use with the crystal Y102.
The clock signal is running on 32kHz as reference for the clock module and as deep sleep
clock.

9 SIM Card Circuit

To allow the use of both 1.8V and 2.8V SIM card types, there is a SIM level-shifter module
in the Locosto-Plus U101. The SIM card digital interface ensures the translation of logic
levels between the Locosto-Plus U101 device and the SIM card J701 for the transmission
of three different signals:
USIM_IO – Data Communications path between SIM connector J701 Pin 2 and
Locosto-Plus Pin P11
USIM_CLK – SIM data Clock from Locosto-Plus Pin P10
USIM_RST – SIM Reset from Locosto-Plus Pin N11
VRSIM is an LDO voltage regulator providing the power supply to the SIM card driver of
the Triton-Lite device.
Service Engineering & Optimization
- 17 -