FLY IQ442 QUAD User manual

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.+TIANYU CONFIDENTIAL
Maintenance Work
Guide for IQ442 QUAD

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INTRODUCTION
This document is the maintenance work guide for IQ442 QUAD. The compile objective
describes the detail theory of IQ442 QUAD and offers a maintenance guide for the later
mass production and after service.
The readers of the document should be the debug worker of SMT and after-service. It will
be the work guide for them. At the same time, the other members of the IQ442 QUAD
project group can also refer to the documents.

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INTRODUCTION ................................................................................................................................. 2
1、System summary ......................................................................................................................... 4
1.1 The diagram of IQ442 QUAD： ........................................................................................... 4
1.2 The main components list: .................................................................................................. 5
2 The details of system model ........................................................................................................... 6
2.1 Radio model ........................................................................................................................ 6
2.1.1 The radio Transceiver ............................................................................................... 6
2.1.2 GSM signal’s path ..................................................................................................... 6
2.1.3 WCDMA signal’s path ............................................................................................... 8
2.2 Power management unit ................................................................................................... 10
2.2.1 The timing of system’s boot ................................................................................... 10
2.2.2 PMU output voltage ............................................................................................... 11
2.3 Memory ............................................................................................................................. 12
2.4 The reference for no- power ON mobile ........................................................................... 12
2.5 Audio model ...................................................................................................................... 13
2.5.1 MIC ......................................................................................................................... 13
2.5.2 Receiver .................................................................................................................. 13
2.5.3 Speaker ................................................................................................................... 14
2.5.4 Audio Jack ............................................................................................................... 14
2.6 Other peripherals .............................................................................................................. 15
2.6.1 Vibrator .................................................................................................................. 15
2.6.2 Touch panel circuit ................................................................................................. 15
2.6.3 Camera ................................................................................................................... 16
2.6.4 Light sensor circuit ................................................................................................. 17
2.6.5 G-sensor ................................................................................................................. 18
2.6.6 Bluetooth & WIFI module....................................................................................... 18
2.6.7 GPS ......................................................................................................................... 20
2.6.8 LCD ......................................................................................................................... 21
2.7 Peripheral interface IO ...................................................................................................... 22
2.7.1 USB interface .......................................................................................................... 22
2.7.2 Side key................................................................................................................... 22
2.7.3 TF Card and USIM Card interface ................................................................................... 23
3. The factory happened case ......................................................................................................... 23
Epilog ....................................................................................................................................... 24

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1、System summary
1.1 The diagram of IQ442 QUAD：
The below is the diagram of IQ442 QUAD, which consist of main function blocks for the
phone. It can help find the root cause for different issues.
Diagram 1.1 The function block
The mobile consists of below main parts:
1. The baseband model:
It contains of the main baseband core parts, it includes the CPU,Memory, PMU etc.
2. The radio model:
It contains of the mobile radio parts; it includes RF6285 IC and other radio parts, for
example RF PA, SAW filter, duplexer, ant switch, and LNA, etc.
3. The audio parts:
It contains the mobile of audio, MIC, speaker, receiver, and headset.

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4. The peripheral parts:
It concludes the peripheral parts of mobile, USB,BT, WIFI,GPS, T-flash, Dual SIM-card,
g-sensor, LCM, Touch panel, front and back camera, light sensor, etc.
1.2 The main components list:
IQ442 QUAD hardware board consists of main board、sub-board、front-camera FPCA and on-key
FPC.
1. the main board parts list:
 U101: It is the system CPU, and it controls baseband、radio、audio、peripheral parts,
such as the TP, side-key, LCM, back light led, g-sensor, light-sensor, motor, cameras,
t-flash card, etc.
 U202: MCP memory of EMMC+SDRAM. EMMC is the AP+BP code; SDRAM is the RAM.
 U802：Power management unit. It is for system power supplies, the system charge,
the system power ON, the SIM care level translation, and monitoring the system
analog ADC.
 U804：DC-DC, it is for CPU core power supply.
 U203 、U204：Load switch, it is for the memory power supply.
 X1101：System clock. It supports the 19.2M system clk.
 U1101： Transceiver which is for radio TX and RX signal.
 U1207：Antenna switch. It is used for different working mode, it also contains the full
mode GMS power amplifier, GSM TX signal is from U1101 to U1207 and it is internal
PA amplifier, to antenna radio.
 U1206：PCS1800 和DCS1900 RX saw filter.
 U1207：GSM850 和EGSM900 RX saw filter.
 U1205：WCDMA BAND 1 TX saw filter.
 U1203：WCDMA BAND 1 TX power amplifier.
 U1210：WCDMA BAND 1 duplexer.
 U1202：WCDMA BAND 8 TX saw filter.
 U1209：WCDMA BAND 8 TX PA。
 U1201: WCDMA BAND 8 duplexer.
 U1602： BT&WIFI 的FEM
 U1604：WIFI IC
 U1607：Bluetooth IC
 J1702：LCM connector
 J1704：Touch panel connector
 U703： the LCM backlight led driver IC
 U1708：g-sensor
 J1501： the connector for main board and sub-board
 J1505：T-flash socket
 U5403、U5404：SIM socket
 J1402： the connector for front camera, light –sensor and Power-ON key
 J1403：The main camera
 J1401：JTAG connector

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 U1401：The flash LED
 U1801，U1803：GPS saw filter
 U1802：GPS LNA
 U501： audio amplifier
 J5460：the volume down/up key
 J5351：headset socket
2 The details of system model
U101 is the AP+BP CPU, U202 is the AP&BP memory, the system can power up while they
are working normally. The bad soldering can cause the system abnormal working.
2.1 Radio model
2.1.1 The radio Transceiver
U1101 is the transceiver which supports GSM and WCDMA mode.
Diagram 2 RF transceiver
2.1.2 GSM signal’s path
1. Tx path
As below diagram 3，the high band (1900/1800)and low band(850/900) come from U1101

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Diagram 3 GSM’s high and low bands signals come out from the U1101
When GSM’s high and low bands come out from U1101, after a resistor attenuator network,
input the U1204 from PIN9 and PIN10，then come out again from U1207’s PIN25 after they be
amplified in it.
Diagram 4 GSM high and low bands signals power amplify
GSM high and low bands signals after through the J1203, then through the RF cable and arrive
J1203 which is on antenna sub board, then after through the antenna match network，were
radiated by the antenna.
Diagram 5 Antenna radio
2. RX path
GSM’s signal was received by antenna，and reach the J1203 on main board after through the
path on Figure 5 and the RF cable .Then the signal enter the U1204 from PIN25（path on the
figure 4 ‘s left part）。 GSM high and low bands signals were divided in U1204 and came out
from U1207’ PIN19 and PIN21 respectively , and then they arrived the saw filter .The high band
signal entered in U1206，The low band signal entered in U1207。When they came out from the
saw filter ,they have become the differential signals .These differential signals enter in the

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U1101 after they through the match network. The path described above can refer to figure 6
and figure 7.
Diagram 6 GSM radio RX
Diagram 7 GSM RX signals into TSC (U1101)
2.1.3 WCDMA signal’s path
IQ442 QUAD supports wcdma band1 and band8.They will be described as below:

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Such above diagram showing, the WCDMA L/H band signals are output from U1101;
TX_WCDMA_LB is low band signal, TX_WCDMA_HB_SE is high band signal.
1. WCDMA BAND 1 TX path:
Band1’s tx signal comes from U1101, and after through some match networks and tx saw filter
U1205, it arrives band1’s PA U1203, then enter in diplexer U1210, then enter the switchU1204.
The below diagram shows the signal path from left to right: the filter, PA, diplexer, and into
U1204 from U1204 PIN17.
Diagram 8 WCDMA BAND1 TX
Band1’s signal comes out from U1204’PIN26.The signal ‘s path after U1204 is same as gsm signal
path .The detail can refer to figure 4 and figure 5 .
Note：From diagram 8, there is a power detector circuit shared by band1 and band8 which is
used to detect the tx power by U1101. The tx signal is power amplifier by PA, the CPL_IN is the
detector net (R1216, R1217, R1218). VMOUDE_0 and VMODE_1 is the modifying the PA gain.
2. WCDMA BAND 8 TX path:
Band 8 tx path is same as band1. The tx signal comes from U1101 ,and then through saw filter
U1202, PA U1209, diplexer U1201,and then enter the U1204.The details was described as below:
from the left to right, the saw filter, pa, diplexer, and ant switch
Diagram 9 WCDMA BAND8 TX
The signal ‘s path after U1204 is same as gsm signal path .The detail can get from figure 4 and
figure 5 .
3. Band1 and band 8 rx path
WCDMA’s rx signal was received by antenna, then through the path described in figure 4 and
figure 5, then arrival the diplexer.
When the BC1 and BC8’s rx signal arrival their diplexer respectively, BC1’s signal comes out

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from U1210’s PIN1, then enter in U1101 after through C1252. BC8’s signal comes out from
U1201’s PIN1and PIN8 which is a differential signal. Then it enters in U1101 after through a
match network and C1201 and C1209.The path was described in figure 10 as below.
Diagram 10 WCDMA BC1 and BC8 RX
After BC1’s signal entered in U1101, in order to improve the SN parameter, The transceiver
amplified the signal first in its internal LNA, and then puts out the BC1‘s signal. The signal was
filtered through U1102, and last they enter the U1101 again. The path described above can
refer to the diagram 11.
Diagram 11 WCDMA BC1 rx LNA
2.2 Power management unit
U802 is the system’s power manager unit，abbreviation PMU. It‘s responsible for system’s
battery’s charge and discharge, boot and shutdown, providing all the power needed by system.
2.2.1 The timing of system’s boot
1. When the power key was pressed down ,or the test point TP1412 was short to ground，
U802’s pin of K11 which was called by name PHONE_ON_N was became low level.
2. PMU initialize, and turn the pinN11 to low，and turn on the switch of system’s power

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MOSFET—U803.
3. PMU puts out all the voltage according to the boot timing.
4. PMU pulls the pin PON_RESET_N to high level，and reset the U101.
5. After the CPU U101 reset, it pulls the PS_HOLD signal to high, in order to keep boot status.
Note：If the power key was pressed up before the PS_HOLD was pulled to high, the phone will
not boot normally.
2.2.2 PMU output voltage
If the system can’t boot normally, we often should to check the voltages put out from the PMU.
PMU output voltage：
Diagram 11 PMU output voltages
After the boot end, all the voltage from PMU and the clock signal should keep stable.

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Diagram 12 DC-DC output for CPU core2
2.3 Memory
SDRAM + NAND Flash Memory save the program code and run the program. If they have some
any problems, the system will not boot up or the system can’t download the system’s program
code.
This part‘s circuit is relatively simple, if the memory has something wrong , we should check the
SMT’s problem first. IF not the SMT’s problem, we should check the memory’s supply
voltages .Such as the voltage on C210/206/C219/C220/C221 should be 1.8V，voltage on
C222/C223/C224 should be 1.2V, the voltage on C214/C215 should be 0.6V. There should be a
clock signal through the resistor R212.
NOTES: there are some cases that AP or BP com port cannot be recognized by PC, the code can’t
be downloaded, it can be shorted TP1520 (or R214) to GND, power on again, the com port can
be founded.
Diagram 13 Memory power
From diagram 13, the power supply 1.8V, 1.2V and 0.6V are memory power; if the U204 or
U203 is not well SMT, the power supply cannot be output, the software can’t be
downloaded.
2.4 The reference for no- power ON mobile
1. The Power ON key is pressed, checking the power current is changed, the USB is recognized
by PC, please check the LCM display, checking the connection of LCM connector.
2. If the power current is always 30—70ma，the USB port can’t be recognized by PC, please
check the Memory first, and the PMU output voltage, the CPU is the final checking.
3. The power current is too high when the power-on key is pressed, and decreased to 0ma,
please check short-circuit, check the PMU output voltages, and find out which one is
shorted.
4. The Power ON/OFF frequency, please check the software issue, or the battery is lower
voltage.
5. The display is frozen after the power on, please check the Memory or the software issue,

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re-download new software.
2.5 Audio model
2.5.1 MIC
U101 can provide the audio signal’s encode and decode functions for the system. So we just
describe the details on the path out of the U101.
The main microphone was welded on the pads printed on the antenna sub board .The
microphone’s differential signal go through the sub board and FPC, and then arrival the U101
after through the filter network which can be referred to figure 14
Diagram 14 main mic
If there is no MIC function, check the component as above diagram firstly, check the R1303
voltage, finally change the new mic or check the signal on MIC path while the MIC function
working.
2.5.2 Receiver
Earpiece’s P/M signal arrival the pads through the filter network as below after they come out
from U101.
Diagram 15 Receiver

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2.5.3 Speaker
Speaker‘s signal come out fromU101, then be amplified by the audio PA U501, drive the speaker.
After be amplified, the speaker’s signal arrival the pads on antenna sub board after through the
FPC and the connector J1501. It need pay attention to U501 SMT issue, which it is bad soldering,
the speaker is no sound. Sometimes there is no sound, please check the PA EN signal, please
check the R539 H level, and checking the C537/C538 soldering.
Diagram 16 Speaker
2.5.4 Audio Jack
1. Earpiece detect circuit
Before the earpiece inserted , the voltage HS_DETECT_N is high level ，When the earpiece
inserted, PMIC_HPH_LS will be low level ,then the CPU detects the event that having a
earpiece be inserted.
2. Headset MIC
Headset MIC is input U101 through matching network, if there is no MIC sound, please check
the MIC bias voltage, checking the ESD component .MB_IN is the headset hook key detecting,
if the hook key is pressed, the MIC is Gnd, MB_IN current is low, CPU will detect the hook
key.
3. Headphones ‘s left and right signal
These signal come out from U101，after through the filter network and beads L104 and
L105.The details can refer to the below diagram.

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Diagram 17 audio jack
2.6 Other peripherals
2.6.1 Vibrator
VBAT is the anode; VIB_DRV_N puts out the low level to drive the vibrator to shock.
VIBA_DRV-N is from U802 to J1501 and through the FPC to sub board to drive vib
Diagram 18 vibrator
2.6.2 Touch panel circuit
The TP is communicating with U101 through the interface IIC.

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Diagram 19 Touch panel
2.6.3 Camera
IQ442 QUAD has a front Camera and a main camera.
1. Main camera circuit
Main Camera is welded on camera FPC, and the peripherals are welded on main board. The
camera and main board connect together through the connector J1403.
Diagram 20 CPU camera IF
The back camera

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Diagram 21 back camera
2. Front camera
The front camera is connected by FPC J1402.
Diagram 22 front camera
2.6.4 Light sensor circuit
Light sensor is communicate with U101 through the IIC interface

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Diagram23 light sensor
Light sensor’s failure often was caused by sealed not well or other devices shared IIC have
something wrong.
2.6.5 G-sensor
The G-sensor is communicated with U101 by I2C.
Diagram 24 G-sensor
2.6.6 Bluetooth & WIFI module
BT and WIFI module was made up of U1602、U1604、U1607. U1602 is the filter for BT and WIFI.
The BT & WIFI is output by ant radio.
Diagram 25 Bluetooth

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Diagram 26 the Bluetooth power
Diagram 27 WIFI & BT ant FEM
Diagram 28 WIFI model

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2.6.7 GPS
The GPS signal through the saw filter U1801, low noise amplifier U1802, saw filter U1803, then
arrivals U1101.
Diagram 29 Gps RF front 图29 GPS 模块 RF 前端电路
Diagram 30 GPS RF to TSC
Diagram 31 GPS IQ to CPU