RT5047
Table 1
SEL Pin Status
COMP Pin Status
LNB Output Voltage
0
0
1
1
0
1
0
1
13.3V
14.3V
18.3V
19.3V
Tone Generation
The RT5047 provides the tone generation function, please refer to the Figure 2. Set the TONE pin with 22kHz logic
signal, the LNB linear regulator output will carry a 22kHz, 700mV peak to peak signal for DiSEqC 1.x communication.
It can meet base-band timings of 500s (±100s) for a one-third bit PWK coded signal period on a nominal 22kHz
(±20 %).
LNB
13.3V or
18.3V
700m
V
VLNB output
TONE when
TONE signal
rise up
VLNB close
TONE after
TONE signal
detect time
TONE signal
detect time
3.3V
TONE
signal
0V
Figure 2. Tone Generation Options
If loading is 1000mA
Pull-Down Rate Control
OCP1=1000mA
25ms
OCP1=1000mA
The output linear stage provides approximately 40mA
of pull-down capability. This ensures that the output
volts are ramped from 18.3V to 13.3V in a reasonable
amount of time.
25ms
OCP2=550mA
20ms
OCP2=550mA
20ms
1800ms
If LNB is shorted to GND
Over-Current Disable Time
OCP1=250mA
25ms
OCP1=250mA
If the LNB output current exceeds 550mA, typical, for
more than 45ms, then the LNB output will be disabled
and device enters a TON = 45ms/TOFF = 1800ms
routine. It will be returned to normal operation after a
successful soft-start process.
25ms
OCP2=138mA
20ms
OCP2=138mA
20ms
1800ms
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is a registered trademark of Richtek Technology Corporation.
DS5047-02 July 2017
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13
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