ADP3522 datasheet(12/20 Pages) AD

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ADP3522

SIMEN

VRTCIN

VRTC

BATSNS

MVBAT

CHRDET

CHRIN

SIMVSEL

VAN

VBAT

VCORE

VMEM

VBAT2

VSIM

GATEDR

PWRON

POWERKEY

SIMEN

VRTC

CHRIN

MVBAT

CHRDET

SIMSEL

CLKON

REFOUT

VTCXO

VAN

VCORE

RESET

VMEM

VSIM

CHGEN

EOC

10 F

0.1 F

2.2 F

C10

2.2 F

0.1 F

0.22 F

Li OR NiMH

BATTERY

BAT1000

SI3441

0.25

COIN CELL

0.1 F

1nF

ADP3522

ROWX

GATEIN

Figure 2. Typical Application Circuit

THEORY OF OPERATION

The ADP3522 is a power management chip optimized for use

with GSM baseband chipsets in handset applications. Figure 1

shows a block diagram of the ADP3522. The ADP3522 con-

tains several blocks, such as:

• Six low dropout regulators (SIM, core, analog, crystal

oscillator, memory, real-time clock)

• Reset generator

• Buffered precision reference

• Lithium ion charge controller and processor interface

• Power on/off logic

• Undervoltage lockout

• Deep discharge lockout

These functions have traditionally been done either as a discrete

implementation or as a custom ASIC design. The ADP3522

combines the benefits of both worlds by providing an integrated

standard product 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

ADP3522. Only a minimal number of support components

are required.

Input Voltage

The input voltage range of the ADP3522 is 3 V to 5.5 V and is

optimized for a single Li-Ion cell or three NiMH cells. The type

of battery, the SIM LDO output voltage, and the memory LDO

output voltage will all affect the amount of power that the

ADP3522 needs to dissipate. The thermal impedance of the

CSP package is 32

°C/W for a JEDEC standard 4-layer board.

The end of charge voltage for high capacity NiMH cells can be as

high as 5.5 V. This results in a worst-case power dissipation for

the ADP3522-1.8 to be as high as 1.6 W for NiMH cells. The

power dissipation for the ADP3522-3 is slightly lower at 1.45 W.

A fully charged Li-Ion battery is 4.25 V, where the ADP3522-3

can dissipate a maximum power of 0.85 W. However, the

ADP3522-1.8 can have a maximum dissipation of 1.0 W.

High battery voltages normally occur 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. The worst-

case power dissipation should be calculated based on the actual

load currents and voltages used.

Figure 3 shows the maximum power dissipation as a function of

the input voltage. Figure 4 shows the maximum allowable

power dissipation as a function of the ambient temperature.

Low Dropout Regulators (LDOs)

The ADP3522 high performance LDOs are optimized for their

given functions by balancing quiescent current, dropout voltage,

regulation, ripple rejection, and output noise. 2.2

µF tantalum

or MLCC ceramic capacitors are recommended for use with the

core, memory, SIM, and analog LDOs. A 0.22

µF capacitor is

recommended for the TCXO LDO.

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