RT5047
Operation
Tone Circuit
The RT5047 integrates a current mode boost converter
and linear regulator. Use the SEL pin to control the
LNB voltage and the boost converter track is at least
greater 850mV than LNB voltage. The boost converter
is the high efficiency PWM architecture with 700kHz
operation frequency. The linear regulator has the
capability to source current up to 550mA during
continuous operation. All the loop compensation,
current sensing, and slope compensation functions are
provided internally.
This circuit is used for tone generation. Use the TONE
pin to control output amplitude of LNB.
OTP
When the junction temperature reaches the critical
temperature (typically 150C), the boost converter and
the linear regulator are immediately disabled.
UVLO
The UVLO circuit compares the VIN with the UVLO
threshold (7.7V rising typically) to ensure that the input
voltage is high enough for reliable operation. The
350mV (typ.) hysteresis prevents supply transients
from causing a shutdown.
OCP
Both the boost converter and the linear regulator have
independent current limit. In the boost converter
(OCP1), this is achieved through cycle-by-cycle
internal current limit (typ. 3A). In the linear regulator
(OCP2), when the linear regulator exceeds OCP more
than 48ms, the LNB output will be disabled and re-start
after 1.8s.
PWM Controller
The loop compensation, current sensing, and slope
compensation functions are provided internally.
Copyright © 2017 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS5047-02 July 2017
www.richtek.com
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