SAMSUNG Proprietary-Contents may change without notice
SGH-P408 Circuit Description
2-
3
This Document can not be used without Samsung's authorization
2. Baseband Circuit description of SGH-P408
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 boost converter provides support for 1.8V, 3.0V, and 5.0V
SIMs, while a self-resetting, electronically fused switch supplies power to
external accessories. Ancillary support functions, such as an LED driver and
two call-alert drivers, aid in reducing both board area and system
complexity.
A three-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.
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 provides fast, efficient charging of a
single-cell Li-ion battery. Used in conjunction with a current-limited voltage
source and an external PMOS pass transistor, 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.
The driver is enabled by EN_LED, and its current setting is determined by
LED[0:2]. Provided EN_LED is '1', the driver can be programmed to sink
from 12.5mA to 100mA in 12.5mA steps. LED_DRV is capable of sinking
100mA 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.