CS35L01/03

DS909A2

15

5. APPLICATIONS

5.1

MODE Descriptions

The CS35L01/03 devices can be operated in one of four operating modes, determined by the MODE pin

and the LFILT+ pin. The four modes of operation are Standard Class-D operation (SD), Reduced Frequency

Standard Class-D operation (FSD), Hybrid Class-D operation (HD), and Reduced Frequency Hybrid Class-

D operation (FHD). Each of these modes can be leveraged to optimize different performance criteria in an

array of applications.

Table 1. LFILT+ and MODE Operation Configurations

5.1.1

Standard Class-D Modes of Operation

5.1.1.1

SD Mode

Standard Class-D (SD) mode supports full audio bandwidth with very good SNR and THD+N perfor-

mance. This mode of operation is characterized by a traditional closed loop, analog

ΔΣ modulated Class-

D amplifier. With an output switching frequency of 192 kHz, this mode ensures flat frequency response

across the entire audio frequency range.

5.1.1.2

FSD Mode

The Reduced Frequency Class-D (FSD) mode provides competitive audio performance and a reduction

in radiated emissions by decreasing the switching frequency of the output devices to 76 kHz. This reduc-

tion in switching frequency reduces the high-frequency energy being created by the output switching

events. Idle channel noise is slightly higher in this mode of operation than SD mode, with the trade-off

being better EMI performance and power consumption.

5.1.2

Hybrid Class-D Modes of Operation

Hybrid Class-D and Reduced Frequency Hybrid Class-D modes of operation allows the rail voltage for the

output devices to switch between a high voltage net and a low voltage net depending on the audio content

being amplified. This is explained in more detail in Section 5.1.2.1 and Section 5.1.2.2. Operation in these

modes requires that the voltage present on the VBATT pin be above the level listed as “VBATT Limit for

and FHD modes of operation of the device will automatically be disabled and operation will be limited to

the SD mode of operation.

MODE connected to:

GND

VBATT

VBATT

Reduced Frequency Class-D Mode

(FSD)

Standard Class-D Mode

(SD)

Filter Cap to Ground

Reduced Frequency Hybrid Class-D Mode

(FHD)

Hybrid Class-D Mode

(HD)