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MT6305B

GSM Power Management System

MediaTek Inc 

Confidential Information

MT6305B

Low Dropout Regulator ( LDOs ) and Reference

The MT6305 Integrates seven LDOs that are opti-

mized for their given functions by balancing quiescent

current, dropout voltage, line/load regulation, ripple

rejection, and output noise.

Digital Core LDO (Vcore)

The digital core LDO is a regulator that could source

200mA (max) with 1.8V or 1.2V output voltage se-

lection based on the supply voltage requirement of

the baseband chipset . It supplies the baseband cir-

cuitry in the handset. The LDO is optimized for very

low quiescent current.

Digital IO LDO (Vio)

The digital IO LDO is a regulator that could source

100mA (max) with 2.8V output voltage. It supplies the

baseband circuitry in the handset. The LDO is opt i-

mized for very low quies cent current and will power

up at the same time as the digital core LDO.

Analog LDO (Va)

The analog LDO is a regulator that could source

150mA (max) with 2.8V output voltage. It supplies the

analog sections of the baseband chipsets. The LDO

is optimized for low frequency ripple rejection in order

to reject the ripple coming from the RF power ampli-

fier burst frequency at 217Hz.

TCXO LDO (Vtcxo)

The TCXO LDO is a regulator that could source 20mA

(max) with 2.8V output voltage. It supplies the tempera-

ture compensated crystal oscillator, which needs its own

ultra low noise supply and very good ripple rejection

ratio.

RTC LDO (Vrtc)

The RTC LDO is a regulator that could source 200µA

(max) with 1.5V or 1.2V output voltage selection

based on the system requirement . It charges up a

capacitor-type backup coin cell to run the real-time

clock module. The LDO features the reverse current

protection and is opt imized for ultra low quiescent

current since it is always on except that battery volt-

age is below 2.5V.

Memory LDO (Vm)

The memory LDO is a regulator that could source

150mA (max) with 1.8V or 2.8V output voltage selec-

tion based on the supply specs of memory chips. It

supplies the memory circuitry in the handset. The

LDO is optimized for very low quiescent current and

will power up at the same time as the digital core

LDO.

SIM LDO (Vsim)

The SIM LDO is a regulator that could source 20mA

(max) with 1.8V or 3.0V output voltage selection

based on the supply specs of subscriber identity

modules (SIM) card. It supplies the SIMs in the

handset. The LDO is controlled independently of the

others LDO.

Reference Voltage Output (Vref)

The reference voltage output is a low noise, high

PSRR and high precision reference with a guaranteed

accuracy of 1.5% over temperature. It is used as sys-

tem reference in MT6305 internally. However for ac-

curate specs of every LDO output voltage, avoid load-

ing the reference voltage and bypass it to GND with

100 nF minimum.

SIM Card Interface

The SIM card interface circuitry of MT6305 meets all

ETSI and IMT-2000 SIM interface requirements. It

provides level shifting needs for low voltage GSM

controller to communicate with either 1.8V or 3V SIM

cards. All SIM cards contain a clock input, a reset

input, and a bi-directional data input/output. The clock

and reset inputs to SIM cards are level shifted from

the supply of digital IO (Vio) of baseband chipset to

the SIM supply (Vsim). The bi-directional data bus is

internal pull high with 20kohm resistor on the control-

ler side and with 10kohm resistor on the SIM side.

All pins that connect to the SIM card (Vsim, SRST,

SCLK, SIO) withstand over 5kV of human body mode

ESD. In order to ensure proper ESD protection, care-

ful board layout is required.

Vibrator, Alerter, LED Switches

Three built-in open-drain output switches drive the

vibrator motor, alerter beeper and LEDs in the hand-

set. Each switch is controlled by baseband chipset

with enable pins. The switch of LED can sink 150mA

to drive up to 10 LEDs simultaneously for backlight.

The switch of vibrator can sink 250mA for a vibrator

motor. The switch of alerter can sink 300mA to drive

the beeper. And all the open-drain output switches

are high impedance when disable.

MediaTek Confidential

Revision 1.1–Apr. 22, 2005

© 2002 MediaTek Inc.

The information contained in this document can be modified without notice

Page 24 of 33

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