CS47L35 datasheet(235/300 Pages) CIRRUS

235 / 300 page

DS1085F3

235

CS47L35

5.1 Recommended External Components

Due to the wide tolerance of many types of ceramic capacitors, care must be taken to ensure that the selected components

provide the required capacitance across the required temperature and voltage ranges in the intended application. For most

application the use of ceramic capacitors with capacitor dielectric X5R is recommended.

5.1.7

Charge-Pump Components

The CS47L35 incorporates two charge-pump circuits (CP1 and CP2).

CP1 generates the CP1VOUTnx supply rails for the ground-referenced headphone drivers; CP2 generates the CP2VOUT

supply rail for the microphone bias (MICBIAS) regulators.

Decoupling capacitors are required on each of the charge-pump outputs. Two fly-back capacitors are required for CP1; a

single fly-back capacitor is required for CP2.

The recommended charge-pump capacitors for CS47L35 are detailed in Table 5-2.

Ceramic capacitors are recommended for these charge-pump requirements. Note that, due to the wide tolerance of many

types of ceramic capacitors, care must be taken to ensure that the selected components provide the required capacitance

across the required temperature and voltage ranges in the intended application. Ceramic capacitors with X5R dielectric

are recommended.

The positioning of the charge-pump capacitors is important. These capacitors (particularly the fly-back capacitors) must

be placed as close as possible to the CS47L35. The component choice and positioning of the CP1 components are more

critical than those of CP2, due to the higher output power requirements of CP1.

5.1.8

External Accessory Detection Components

The external accessory detection circuit measures jack insertion using the JACKDET1 and JACKDET2 pins. The insertion

switch status is detected using an internal pull-up resistor circuit on the respective pin. Note that the logic thresholds

associated with the two JACKDET differ from each other, as described in Table 3-11—this provides support for different

jack switch configurations.

Microphone detection and key-button press detection is supported using the MICDETn pins. The applicable pin should be

connected to one of the MICBIASnx outputs, via a 2.2-k

 bias resistor, as described in Section 5.1.3. Note that, when

using the external accessory detection function, the MICBIASnx resistor must be 2.2 k

 ±2%.

A recommended circuit configuration, including headphone output on HPOUT and microphone connections, is shown in

Fig. 5-11. See Section 5.1.1 for details of the DC-blocking microphone input capacitor selection.

The recommended external components and connections for microphone/push-button detection are shown in Fig. 5-11.

Note that, when using the microphone detect circuit, it is recommended to use the IN1BLP or IN1BRP analog microphone

input paths to ensure best immunity to electrical transients arising from the external accessory.

Table 5-2. Charge-Pump External Capacitors

Description

Capacitor

CP1VOUT1P decoupling

Required capacitance is 2.0

F at 2 V.

Suitable component typically 4.7

F.

CP1VOUT1N decoupling

Required capacitance is 2.0

F at 2 V.

Suitable component typically 4.7

F.

CP1 fly-back 1

(connect between CP1C1A and CP1C1B)

Required capacitance is 1.0

F at 2 V.

Suitable component typically 2.2

F.

CP1VOUT2P decoupling

Required capacitance is 2.0

F at 2 V.

Suitable component typically 4.7

F.

CP1VOUT2N decoupling

Required capacitance is 2.0

F at 2 V.

Suitable component typically 4.7

F.

CP1 fly-back 2

(connect between CP1C2A and CP1C2B)

Required capacitance is 1.0

F at 2 V.

Suitable component typically 2.2

F.

CP2VOUT decoupling

Required capacitance is 1.0

F at 3.6 V.

Suitable component typically 4.7

F.

CP2 fly-back

(connect between CP2CA and CP2CB)

Required capacitance is 220 nF at 2 V.

Suitable component typically 470 nF.

CS47L35 Datasheet(PDF) 235 Page - Cirrus Logic

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