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ADP3405ARU Ver la hoja de datos (PDF) - Analog Devices

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Lista de partido
ADP3405ARU
ADI
Analog Devices ADI
ADP3405ARU Datasheet PDF : 12 Pages
1 2 3 4 5 6 7 8 9 10 Next Last
ADP3405
600
500
VCCA
400 TCXO
FULL LOAD
MLCC CAPS
300
200
REF
100
0
10
100
1k
10k
100k
FREQUENCY Hz
TPC 13. Output Noise Density
THEORY OF OPERATION
The ADP3405 is a power management chip optimized for use with
the AD20msp425 GSM baseband chipsets in handset applications.
Figure 1 shows a functional block diagram of the ADP3405.
The ADP3405 contains several blocks:
Four Low Dropout Regulators (Digital, Analog, Crystal
Oscillator, Real-Time Clock)
Reset Generator
Buffered Precision Reference
SIM Interface Logic Level Translation (3 V/5 V)
SIM Voltage Supply
Power-On/-Off Logic
Undervoltage Lockout
These functions have traditionally been done as either a discrete
implementation or a custom ASIC design. ADP3405 combines
the benefits of both worlds by providing an integrated standard
product solution where every block is optimized to operate in a
GSM environment while maintaining a cost-competitive solution.
Figure 2 shows the external circuitry associated with the ADP3405.
Only a few support components, mainly decoupling capacitors,
are required.
Input Voltage
The input voltage range for ADP3405 is 3 V to 7 V and optimized
for a single Li-Ion cell or three NiMH/NiCd cells. The thermal
impedance (θJA) of the ADP3405 is 62°C/W for 6-layer boards.
The charging voltage for a high capacity NiMH cell can be as high
as 5.5 V. Power dissipation should be calculated at maximum
ambient temperatures and battery voltage in order not to exceed
the 125°C maximum allowable junction temperature. Figure 3
shows the maximum total LDO output current as a function of
ambient temperature and battery voltage.
However, high battery voltages normally occur only when the
battery is being charged and the handset is not in conversation
mode. In this mode there is a relatively light load on the LDOs.
A fully charged Li-Ion battery is 4.25 V, where the LDOs deliver
the maximum 240 mA up to the max 85°C ambient temperature.
ANALOG GND
DIGITAL AND
SIM GND
100nF
0.22F
100nF
10
2.2F
1 LI-ION
OR
3 NIMH
CHARGER
INPUT
10F
2.2F
GSM
PROCESSOR
R1
R2
1 RESCAP
CAP+ 28
2 DGND
VSIM 27
3 VTCXO
CLK 26
4 RESET
SIMON 25
5 REFOUT
SIMPROG 24
6 VCCA ADP3405 RST 23
7 AGND
I/O 22
8 VBAT
SIMGND 21
9 VCC
CLKIN 20
10 PWRONKEY
RESETIN 19
11 ANALOGON
DATAIO 18
12 PWRONIN
SIMBAT 17
13 ROWX
CAP16
14 CHRON
VRTC 15
TSSOP-28
10F
CLK TO SIM CARD
GSM
PROCESSOR
RST TO SIM CARD
I/O TO SIM CARD
SIM PINS
OF
GSM PROCESSOR
100nF
100nF
BACK-UP
COIN CELL
10F
Figure 2. Typical Application Circuit
REV. 0
–9–

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