SSM4567ACBZ-R7 datasheet(25/52 Pages) AD

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Data Sheet

SSM4567

Rev. 0| Page 25 of 52

When high output is not needed, ensure no efficiency loss due

to the extra boost switch by switching off the battery supply.

With variable boost methods after high output is no longer

needed, the boost remains on for a long time. With five-level

modulation, it instantly switches back to using the battery

supply, resulting in better real-world power. Figure 53 depicts

five-level, Σ-Δ output modulation with input stimulus.

Figure 53. Five-Level, Σ-Δ Output Modulation

INTEGRATED BOOST CONVERTER

An integrated boost converter is provided with a nominal

switching frequency of 1.536 MHz. The converter is designed to

step up the VBAT supply, typically 3.6 V from a single-cell

battery, to a higher VOUT voltage of 5.1 V. The output of the

boost converter is available at the VBST pins. A 2.2 µH inductor

is required for proper operation of the boost converter. See the

Component Selection for Boost Regulators section for more details

on selecting the proper inductor. The boost converter can be

powered down via the BOOST_PWDN control bit. When the

boost is powered down and the amplifier is still active, the

amplifier runs directly off the VBAT supply. This same VBAT

only operation can be entered with the boost still active with the

VBAT_ONLY bit. The amplifier can be powered down with the

boost still enabled so that the boost output can be used for other

functions.

+VBST

+VBAT

–VBAT

–VBST

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