IC-TW28 Datasheet, PDF (39/80 Pages) IC-Haus GmbH – 10-BIT SIN/COS INTERPOLATOR

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Rev D2, Page 39/80
LED_CFG
LED_CFG is a static register used to configure the LED
intensity control feature of the iC-TW28. See LED Inten-
sity Control on page 72 for more information on using
this feature.
Value
0
1
LED_CFG.auto (0x0001 Bit 3)
Description
LED intensity control off
LED intensity control on
Table 39: LED Intensity Control
LED_CFG.en enables or disables the LED pin.
Value
0
1
LED_CFG.en (0x0001 Bit 0)
Description
LED pin disabled
LED pin enabled
Table 35: LED Output Enable
If LED_CFG.en = 0, the LED output pin is in the state
shown below.
LED Pin State (LED_CFG.en = 0)
LED_CFG.odrain
LED_CFG.pol
0
0
0
1
1
X
State
Low
High
Hi-Z
If LED_CFG.en = 0, LED_CFG.auto has no effect. If
LED_CFG.en = 1 and LED_CFG.auto = 0, the signal on
the LED output is the value of LED_START.
LED_CFG.freq selects the DSM (Delta-Sigma Modu-
lation) frequency of the LED intensity control output.
The corresponding PWM frequency is shown for use in
selecting filter components.
Value
0
1
2
3
LED_CFG.freq (0x0001 Bits 5:4)
DSM Frequency
PWM Frequency
3.125 MHz
12.2 kHz
6.25 MHz
24.4 kHz
12.5 MHz
48.8 kHz
25 MHz
97.6 kHz
Table 40: LED Modulation Frequency
Table 36: LED Pin State (LED_CFG.en = 0)
LED_CFG.pol selects the polarity of the LED PWM
signal.
Value
0
1
LED_CFG.pol (0x0001 Bit 1)
Description
Positive polarity
Negative polarity
Table 37: PWM Polarity
LED_CFG.buffer is used to set the hysteresis of the
LED intensity control.
Value
0
1
2
3
LED_CFG.buffer (0x0001 Bits 7:6)
Buffer
8
16
24
32
Table 41: LED Control Loop Buffer
With positive LED polarity, a larger PWM value results
in more high time in the LED PWM signal. With nega-
tive LED polarity, a larger PWM value results in more
low time in the LED PWM signal. If LED_CFG.en = 0,
LED_CFG.pol has no effect.
If LED_CFG.en = 1 and LED_CFG.auto = 1, the LED
intensity control increases the duty cycle of the LED
PWM signal whenever SC_AMP < (SC_AMP_LOW +
LED_CFG.buffer) and decreases it whenever SC_AMP
> (SC_AMP_HIGH – LED_CFG.buffer). For proper
operation,
LED_CFG.odrain selects whether the LED output is
SC_AMP_HIGH − SC_AMP_LOW
open-drain or push-pull.
LED_CFG.buffer <
2
Value
0
1
LED_CFG.odrain (0x0001 Bit 2)
Description
Push-pull LED output
Open-drain LED output
Table 38: LED Output Configuration
If LED_CFG.en = 0, or if LED_CFG.en = 1 and
LED_CFG.auto = 0, LED_CFG.buffer has no effect.
If LED_CFG.en = 0, LED_CFG.odrain has no effect.
LED_CFG.auto enables and disables the LED intensity
control.