DS963F5

21

CS35L32

4.9 LED Driver

4.8.4

Monitoring Voltage on the VP Pin—VPMON

Monitoring of the voltage present on the VP pin is integrated internally to the CS35L32. The operating specifications for

this ADC path are given in Table 3-7. To determine the voltage present on VP, the following equation must be used:

4.8.5

Data Transmission out of the CS35L32

The ADSP, described in Section 4.11, can transmit all signals monitored in the CS35L32 to the system processor. The

data is presented on these outputs simultaneously.

4.8.6

Error Conditions

The CS35L32 monitors each monitoring ADC for overflow conditions. Table 4-4 lists signal monitoring error conditions and

provides links to their associated register field descriptions.

If an overflow occurs, the appropriate xMON_OVFL bit is set, and, if the respective mask bit is cleared, an interrupt occurs.

Exiting the error occurs when the signal is no longer overflowing. No release bit needs to be toggled.

• Overflow for VPMON and VMON signals. Due to the analog prescaling applied to the analog input signals, which

are sampled to make the VPMON and VMON signals, overflow conditions are unlikely on these ADCs. This is

because the operating specifications for maximum and minimum voltage constrain the voltage on these pins to a

level far below that required to make the ADC overflow.

For VPMON, because a spurious overflow error can occur when the block is taken out of power down, it is advised

to read the error status registers after PDN_xMON has been cleared to clear the spurious error status bit.

• Overflow for the IMON signal. As Section 4.8.3.1 describes, the IMON_SCALE (see p. 38) control allows the

greatest possible sample resolution over a wide range of output currents and sense resistors. If IMON_SCALE is

set too low for either the output current being monitored or the sense resistor being used, overflow of this ADC can

occur. When this error occurs, increasing the IMON_SCALE value can prevent the sampled signal from overflowing.

4.9 LED Driver

The CS35L32 includes a high-current flash LED driver (see Fig. 4-6), featuring two channels, FLOUT1 and FLOUT2, and

a boost converter and current regulator designed to power LEDs with up to 0.75 A per channel. Both channels can be

combined to drive an LED with 1.5 A by tying FLOUT1 and FLOUT2 together.

Figure 4-6. LED Driver Block Diagram

Table 4-4. Signal Monitoring Error Status Conditions

Error

Cross-Reference to Description

xMON overflow. Indicates the overrange

status in the VMON, IMON, or VPMON

ADC signal paths.

VMON_OVFL p. 42

IMON_OVFL p. 42

VPMON_OVFL p. 42

VP

DOUT 128

+



255

--------------------------------------- 5



1

1.8

--------

+



 VA



=

Flash LED Current Drivers

Control,

Sensing,

and Fault

Protection

FLOUT1

FLOUT2/AD0

FLEN FLINH

Current Mode

Boost Controller

GNDPLED

LED_FLINHCUR

on p. 44

LED_FLCUR on p. 43

LED_MVCUR on p. 44

TIMER on p. 44

TIMEOUT_MODE on p. 44