AS3658 datasheet(81/158 Pages) AMSCO

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Table 79. LDOs Reg Power2ctrl Bit definitions

Addr:30

Reg Power2 Ctrl

These bits control the on/off function of the ldo regulator

Bit

Bit Name

Default Access

Description

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AS3658

Data Sheet Confidential - Detail ed Descri ption-Power Management Functions

8.12.1 RF LDO’s (VRF_1, VRF_2, VRF_3)

These LDO’s are designed to supply sensitive analogue circuits like LNA’s, Transceivers, VCO’s and other critical RF

components of cellular radios. Another application is the supply of audio devices or as a reference for AD and DA

converters. The design is optimized to deliver the best compromise between quiescent current and regulator

performance for battery powered devices.

Stability is guaranteed with ceramic output capacitors of 1µF ±20% (X5R) or 2.2µF +100/-50% (Z5U) for RF2, RF3 and

2.2µF ±20% (X5R) or 4.7µF +100/-50% (Z5U) for RF1. The low ESR of these caps ensures low output impedance at

high frequencies. Regulation performance is excellent even under low dropout conditions, when the power transistor

has to operate in linear mode. Power supply rejection is high enough to suppress the PA-ripple on the battery in TDMA

systems at the output. The low noise performance allows direct connection of noise sensitive circuits without additional

filtering networks. The low impedance of the power device enables the device to deliver up to IOUT current even at

nearly discharged batteries without any decrease of performance.

With vrf2_lcurr_en=0 and vrf3_lcurr_en=0 the regulator VRF_2, VRF_3 can deliver up to 250mA

With vrf1_lcurr_en=0 the regulator VRF_1 can deliver up to 400mA

ldo_rf3_on

ROM

R/W

Switch on control of RF3 LDO; Important: Set rf3_sw=0

before setting ldo_rf3_on=1

ldo_dig3_on

ROM

R/W

Switch on control of DIG3 LDO; it is possible to on/off

control LDO DIG_3 by CURR3_GPIO3 or CURR4_GPIO4

(see General Purpose Input / Output (CURR1_GPIO1 …

CURR4_GPIO4) on page 30)’

ldo_dig4_on

ROM

R/W

Switch on control of DIG4 LDO

rf1_sw

ROM

R/W

If ‘1’ RF1-LDO is operating as High side switch (Ron=1

Ω),

valid if ldo_rf1_on=0

rf2_sw

ROM

R/W

If ‘1’ RF2-LDO is operating as High side switch (Ron=1

Ω),

valid if ldo_rf2_on=0

rf3_sw

ROM

R/W

If ‘1’ RF3-LDO is operating as High side switch (Ron=1

Ω),

valid if ldo_rf3_on=0

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