RT5047

Copyright © 2017 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

DS5047-02

July

2017

www.richtek.com

13

Table 1

SEL Pin Status

COMP Pin Status

LNB Output Voltage

0

0

13.3V

0

1

14.3V

1

0

18.3V

1

1

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 500

s (±100s) for a one-third bit PWK coded signal period on a nominal 22kHz

(±20 %).

TONE

signal

0V

3.3V

13.3V or

18.3V

700m

V

LNB

TONE signal

detect time

VLNB close

TONE after

TONE signal

detect time

VLNB output

TONE when

TONE signal

rise up

Figure 2. Tone Generation Options

Pull-Down Rate Control

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.

Over-Current Disable Time

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.

OCP1=1000mA

25ms

OCP2=550mA

20ms

If loading is 1000mA

1800ms

OCP1=1000mA

25ms

OCP2=550mA

20ms

OCP1=250mA

25ms

OCP2=138mA

20ms

If LNB is shorted to GND

1800ms

OCP1=250mA

25ms

OCP2=138mA

20ms