Cirrus Logic CS35L32 - Manual (Page 18)

18 DS963F4
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 I 2 S 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.
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
VP VBST
VP SW
Rectifying FET
GNDP
Boost Controller
2-MHz Clock Set
Reset
Pulse
Width
Control
R
BST_SNS
IREF
GEN
V
BANDGAP
Internal
Reference
Circuitry
IREF+
C
BST(OUT)
C
BST(IN)
Boost
FET
L
BST
BST_IPK
on p. 38
Die Temperature Monitoring
Temperature
Sensor
VA
V
BANDGAP
Overtemperature Error Reference (T
OP
)
V
BANDGAP
Overtemperature Warning Reference (T
WRN
)
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 )