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2. SGH-X430 Circuit Description
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2. Baseband
Circuit description of SGH-X430
1) PSC2106
1. Power Management
Seven low-dropout regulators designed specifically for GSM applications
power the terminal and help ensure optimal system performance and long
battery life.
A programmable LDO provides support for 1.8V, 3.0V SIMs, while a
self-resetting, electronically fused switch supplies power to external
accessories. Ancillary support functions, such as two LED drivers and two
call-alert drivers, aid in reducing both board area and system complexity.
A four-wire serial interface unit(SIU) provides access to control and
configuration registers. This interface gives a microprocessor full control of
the PSC2106 and enables system designers to maximize both standby and
talk times. Error reporting is provided via an interrupt signal and status
register.
Supervisory functions. including a reset generator, an input voltage monitor,
and a thermal monitor, support reliable system design. These functions
work together to ensure proper system behavior during start-up or in the
event of a fault condition(low microprocessor voltage, insufficient battery
energy, or excessive die temperature).
2. Battery Charge Management
A battery charge management block, incorporating an internal PMOS switch,
and an 8-bit ADC, provides fast, efficient charging of single-cell Li-Ion
battery. Used in conjunction with a current-limited voltage source, this block
safely conditions near-dead cells and provides the option of having
fast-charge and top-off controlled internally or by the system's
microprocessor.
3. Backlight LED Driver
The backlight LED driver is a low-side, programmable current source
designed to control the brightness of the keyboard and LCD illumination.
LED1_DRV is controlled via LED1_[0:2] and can be programmed to sink
from 15mA to 60mA in 7.5mA steps. LED2_DRV is controlled via LED2_
[0:2] and can be programmed to sink from 5mA to 40mA in 5mA steps.
Both LED drivers are capable of sinking their maximum output current at a
worst-case maximum output voltage of 0.6V. For efficient use, the LEDs is
connected between the battery and the LED_DRV output.
