ADP3402 Analog Devices, ADP3402 Datasheet - Page 9

• Manufacturer Part Number: ADP3402
• Description: GSM Power Management System
• Manufacturer: Analog Devices

THEORY OF OPERATION
The ADP3402 is a power management chip optimized for use
with GSM baseband chipsets in handset applications. Figure 1
shows a block diagram of the ADP3402.
The ADP3402 contains several blocks:
• Four Low Dropout Regulators (Digital, Analog, Crystal
• Reset Generator
• Buffered Precision Reference
• SIM Interface Logic Level Translation (3 V/5 V)
• SIM Voltage Supply
• Power On/Off Logic
• Undervoltage Lockout
REV. 0
Oscillator, Real-Time Clock)
CHARGER INPUT
600
500
400
300
200
100
0
10
BACKUP COIN CELL
CAPACITOR-TYPE
1 Li-ION OR
TCXO
Figure 14. Output Noise Density
GSM PROCESSOR
REF
3 NiMH
CELLS
SIM PIN OF
VCCA
PROCESSOR
GSM
100
R2
FREQUENCY – Hz
100nF
R1
1k
100nF
10 F
10 F
10k
Figure 15. Typical Application Circuit
2.2 F
FULL LOAD
MLCC CAPS
10
11
12
13
14
1
2
3
4
5
6
7
8
9
CLKIN
SIMGND
SIMBAT
DATAIO
RESETIN
VBAT
VCC
PWRONIN
ROWX
CHRON
VRTC
CAP–
PWRONKEY
ANALOGON
100k
–9–
ADP3402
These functions have traditionally been done either as a discrete
implementation or as a custom ASIC design. ADP3402 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 15 shows the external circuitry associated with the ADP3402.
Only a few support components, mainly decoupling capacitors,
are required.
Input Voltage
The input voltage range for ADP3402 is 3 V to 7 V and optimized
for a single Li-Ion cell or three NiMH/NiCd cells. The ADP3402
uses Analog Devices’ patented package thermal enhancement tech-
nology, which allows 15% improvement in power handling capabil-
ity over standard plastic packages. The thermal impedance (
the ADP3402 is 60 C/W. 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 tem-
perature. Figure 16 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.
SIMPROG
RESCAP
REFOUT
VTCXO
RESET
SIMON
AGND
DGND
VCCA
CAP+
VSIM
CLK
RST
I/O
28
27
26
25
24
23
22
21
20
19
18
17
16
15
10 F
100
10 F
2.2 F
0.22 F
100nF
CLK TO SIMCARD
RST TO SIMCARD
I/O TO SIM CARD
PROCESSOR
GSM
ADP3402
ANALOG GND
DIGITAL AND
SIM GND
JA
) of