CS35L32 Datasheet, PDF (18/51 Pages) Cirrus Logic – Boosted Class D Amplifier with Speaker-Protection Monitoring and Flash LED Drivers

CS35L32
4.5 Undervoltage Lockout (UVLO)
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.
MCLK_INT sets the frequency of the converter to 2 MHz. MCLK_INT is derived from MCLK by setting MCLKDIV2 (see p. 37).
If MCLK_INT stops switching, the converter is placed in Bypass Mode until clocking is restored.
VP
LBST
VBST
C_BST(IN)
R_{BST_SNS}
VP
Internal
Reference
Circuitry
SW ^{Boost Converter}
Rectifying FET
IREF+
Boost
FET
V_{BANDGAP IREF}
BST_IPK ^GEN
on p. 38 _GNDP
Boost Controller
Set
Reset
2-MHz Clock
Pulse
Width
Control
C_{BS T(OUT )}
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.
OTE on p. 41
M_OTE on p. 40
OTE_RLS on p. 40
(see Section 4.7.1)
OTW on p. 41
M_OTW on p. 40
(see Section 4.7.1)
Die Temperature Monitoring
Overtemperature Error Reference(T_OP) VBANDGAP
VA
Temperature
Sensor
Overtemperature Warning Reference(T_WRN) V_BANDGAP
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).
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DS963F5