Smart Machine Smart Decision
8
2.
Detail Block Diagram
MSM8909
eMMC flash +
LPDDR3
EBI1
SDC1
GPIO
Keypad Buttons
I2C
SPI
UART * 2
4 Lanes DSI
2 Lanes CSI
1 Lanes CSI
USB
UIM1
UIM2
SDC2
Earpiece
Microphone
Headset
TP/Sensor/Cam/others
Vibrator
Keypad Buttons
CODEC
Linear
Charger
Output Power
Management
PM8909
19.2M XO
PDM BUS
Primary Camera (8MP)
720P LCD
Secondary Camera (5MP)
USB HS (Support OTG)
UIM Card2
SD Card
UIM Card1
VBUS_5V
VBAT
ADC
Speaker
4G/3G/2G MODEM
Core
MODEM/Voice
Processor
GNSS
Baseband
Modem
Jolokia
WWAN RX I/Q
GSM Phase
WWAN TX I/Q
RFFE
GNSS I/Q
WTR4905
Front End
MMMB
Power
Amplifier
Modele
RFFE
RFFE
3
rd
party
PA+SW
DIVERSITY
SWITCH
MODULE
MAIN
DRX
BT/WIFI
Baseband
Codec Digital
AP
Quad A7 w/ 512K L2
Camera ISP/VFE/Jpeg HW
Display Processor
Video
Graphics
Peripherals
SPMI BUS
Memory Support
Note2
Figure 3: Block diagram of SIM8905A
3.
Interface Application
Power Supply
The power supply pins of SIM8905A include VBAT_RF and VBAT_BB. VBAT_RF directly supplies the power
to RF PA; VBAT_BB supplies the power to the baseband system. The power supply of SIM8905A ranges from
3.4V to 4.4V, and 3.9V is recommended. It must be able to provide sufficient current up to 3A for the high-power
transmitting.
If the DC input voltage is +5V and customers do not care about the power efficiency, a high-current low-dropout
regulator is recommended. Figure 4 is the reference design.
Vin
Vout
GND
FB
3
+
PWR_CTRL
R102
R101
VBAT
100K
47K
+
C103
330uF
C104
100nF
U101 MIC29302
5
4
1
2
C101
C102
100uF
1uF
DC INPUT
R103
470R
On/Off
Figure 4: LDO power supply reference circuit
Note: To ensure a proper behavior of the regulator under light load, an extra minimum load (R103 in
Figure
4)
is required, because the current SIM8905A consumed is very small in sleep mode and power off mode. For
more details about minimum load, please refer to specification of MIC29302.
