ADP3402 Просмотр технического описания (PDF) - Analog Devices

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ADP3402

GSM Power Management System

Analog Devices 

600

500

VCCA

400 TCXO

FULL LOAD

MLCC CAPS

300

200

REF

100

0

10

100

1k

10k

100k

FREQUENCY – Hz

Figure 14. Output Noise Density

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

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

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 (θJA) of

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.

CHARGER INPUT

1 Li-ION OR

3 NiMH

CELLS

R1

10␮F

GSM

PROCESSOR

R2

CAPACITOR-TYPE

BACKUP COIN CELL

100nF

100nF

10␮F

SIM PIN OF

GSM PROCESSOR

1 VBAT

AGND 28

2 VCC

2.2␮F

3 PWRONKEY

4 ANALOGON

VCCA 27

REFOUT 26

RESET 25

100⍀ 2.2␮F

10␮F

5 PWRONIN

6 ROWX

7 CHRON

8 VRTC

ADP3402

VTCXO 24

DGND 23

RESCAP 22

CAP+ 21

0.22␮F

100nF

ANALOG GND

DIGITAL AND

SIM GND

9 CAP–

10 SIMBAT

VSIM 20

10␮F

CLK 19

CLK TO SIMCARD

11 DATAIO

12 RESETIN

SIMON 18

SIMPROG 17

GSM

PROCESSOR

13 CLKIN

RST 16

RST TO SIMCARD

14 SIMGND

I/O 15

I/O TO SIM CARD

Figure 15. Typical Application Circuit

REV. 0

–9–

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