CS35L32 datasheet(18/51 Pages) CIRRUS

18 / 51 page

DS963F5

CS35L32

4.5 Undervoltage Lockout (UVLO)

If the VP level falls below the lockout threshold specified in Table 3-3, UVLO protection shuts down all analog circuitry of

the CS35L32. Autorecovery occurs as VP rises above the lockout threshold by a voltage equal to the specified hysteresis.

During a UVLO condition, control port, UVLO detection, serial clock, watchdog, and thermal detection circuitry stay active.

Note:

During an UVLO condition, the I2S port is automatically powered down, preventing the UVLO condition from being

fed back via the ADSP SDOUT pin.

4.6 Boost Converter

The CS35L32's boost converter, shown in Fig. 4-3, delivers power to the supply of the audio speaker amplifier as well as

to the LEDs. Its output voltage is determined by VBOOST_MNG (see p. 38). Section 4.10 further shows how VBOOST_

MNG relates to audio and LED operation. The boost converter features a current-limiting circuit that detects and clamps

peak inductor current if such a peak is equal to the user-programmable limit (BST_IPK, see p. 38). BOOST_CURLIM

interrupt flag is set when the current limit has been detected.

MCLKINT sets the frequency of the converter to 2 MHz. MCLKINT is derived from MCLK by setting MCLKDIV2 (see p. 37).

If MCLKINT stops switching, the converter is placed in Bypass Mode until clocking is restored.

Figure 4-3. Boost Controller Block Diagram

4.7 Die Temperature Monitoring

Onboard die temperature monitoring prevents, shown in Fig. 4-4, the CS35L32 from reaching a temperature that would

compromise reliability or functionality. The CS35L32 incorporates a two-threshold thermal-monitoring system. When die

temperature exceeds the lower threshold, an overtemperature warning (OTW) event occurs; if it exceeds the second

threshold, an overtemperature error (OTE) condition occurs. These conditions are described in Section 4.7.1.

Figure 4-4. Die Temperature Monitoring

Note:

The CS35L32 does not support independent powering down of die-temperature monitoring circuitry (other than

powering it down via PDN_ALL, see p. 36).

Boost Converter

VBST

Rectifying FET

GNDP

Boost Controller

2-MHz Clock

Set

Reset

Pulse

Width

Control

RBST_SNS

IREF

GEN

VBANDGAP

Internal

Reference

Circuitry

IREF+

CBST(OUT)

CBST(IN)

Boost

FET

LBST

BST_IPK

on p. 38

Die Temperature Monitoring

Temperature

Sensor

VBANDGAP

Overtemperature Error Reference(TOP)

VBANDGAP

Overtemperature Warning Reference(TWRN)

OTW on p. 41

M_OTW on p. 40

(see Section 4.7.1)

OTE on p. 41

M_OTE on p. 40

OTE_RLS on p. 40

(see Section 4.7.1)

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