Circuit Description - Samsung SCH-A310 Service Manual

6. Circuit Description

6-1 Logic Section
6-1-1 Power Supply
To power on the phone, Pressing the PWR key with
the battery installed will short the V_BAT and
ON_SW signal. The V_DC, which is connected with
V_BAT, will be turned on simultaneously, The V_PD
and V_IF LDOs outputs of Regulator(U201, U322)
are turned on assuming V_BAT is greater than
2.85V.
Pressing the PWR key(
END/
seconds, The V_BAT voltage is applied to the
ON_SW, the ON_SW signal will transition high
when the PWR_HOLD signal is high.
The low state ONO\signal will be detected by the
MSM, when PWR_HOLD signal is high, to set the
PWR_HOLD signal low and power off the phone.
Once the PWR_HOLD signal is low all the LDOs
output of the Regulator(U201, U322)will be
powered off after typically 60ms delay and all the
logic of the PMIC will be reset to the shutdown
condition.
The V_PD output voltage of Regulator(U201) is
connected with V_MEM(used in memory),
V_LCD(used in LCD), V_MSMD(used in the digital
parts of MSM).
6-1-2 Inner Charging Circuit Part
The most important function of the charger shall be
done in the LTC1734(U240).
When the phone attached a battery is connected
with travel charging adapter, the inner charging
circuit of the LTC1734(U240) will charge by the
constant fast charge current.
When battery reaches regulation voltage of 4.2V
(default charging voltage for Li+mode), the charge
current drops quickly to 0mA by the programmed
data of the LTC1734 controlled from the MSM.
-Input voltage range : 4.75~8V
-Charging Temperature :0°C~40°C
)of the keypad for a few
SAMSUNG Proprietary-Contents may change without notice
-Charging Method : Constant Voltage/Current
-Charging Current : Max 550mA
-Charging Time : Standard (550mAh) 1.5 ~ 2 Hrs
Extended (900mAh) 3 ~ 3.5 Hrs
-Charging Mode : 1. Charging - RED Lamp
2. Completion -GREEN Lamp
-Charging Battery Regulation Voltage
1. Min 4.158V, Typical 4.2V, Max 4.242V
(at T : 0°C to +85°C)
A
2. Min 4.137V, Typical 4.2V, Max 4.263V
(at T : -40°C to +85°C)
A
-Over Battery Protection Voltage : Typical 5.2V
Universal Serial Bus Interface(U250)
SCH-A310 supports a Universal Serial Bus(USB)
interface, by the MSM 5100, to provide an efficient
interconnection between the mobile phone and a
Personal Computer(PC).
The MSM 5100's USB interface is designed to
comply with the Universal Serial Bus Specification,
Revision 1.1.
The USB interface of SCH-A310 and can be used to
transfer over-the-air data, or voice PCM samples
between the mobile phone and the USB host.
An external USB transceiver(U250) and 48MHz
crystal oscillator(OSC110) are required to implement
the USB interface.
6-1