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PDF RT5070 Data sheet ( Hoja de datos )
| Número de pieza | RT5070 | |
| Descripción | Single Output LNB Supply and Control Voltage Regulator | |
| Fabricantes | Richtek | |
| Logotipo |  |
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RT5070
Single Output LNB Supply and Control Voltage Regulator
General Description
The RT5070 is a highly integrated voltage regulator
and interface IC, specifically design for supplying
power and control signals from advanced satellite
set-top box (STB) modules to the LNB down-converter
in the antenna dish or to the multi-switch box.
The device is consists of the independent current-mode
boost controller and low dropout linear regulator for the
LNB power.
The RT5070 has fault protection (over-current,
over-temperature and under-voltage lockout).
The RT5070 are available in a SOP-8 (Exposed Pad)
package to achieve optimized solution for thermal
dissipation.
Ordering Information
RT5070
Package Type
SP : SOP-8 (Exposed Pad-Option 2)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Note :
Richtek products are :
RoHS compliant and compatible with the current
requirements of IPC/JEDEC J-STD-020.
Suitable for use in SnPb or Pb-free soldering
processes.
Features
Wide Input Supply Voltage Range : 8V to 16V
Output Current Limit of 550mA with 45ms Timer
Low Noise LNB Output Voltage (13.3V and 18.3V
by SEL Pin)
+/-3% High Accuracy for 0mA to 500mA Current
Output
Push-Pull Output Stage Minimizes 13.3V to
18.3V and 18.3V to 13.3V Output Transition Time
Output Short Circuit Protection
Over-Temperature Protection
Applications
LNB Power Supply and Control for Satellite Set-Top
Box
Analog and Digital Satellite Receivers/ Satellite TV,
Satellite PC cards
Pin Configurations
(TOP VIEW)
LNB
BOOST
LX
VIN
8
27
GND
36
9
45
GND
FAULT
SEL
EN
SOP-8 (Exposed Pad)
Simplified Application Circuit
L1 D1
VIN
CIN1
CIN2
LX
VIN
BOOST
3.3V
R1
EN
SEL RT5070 LNB
FAULT
GND
CBST
Max. 550mA
D3
D2
CLNB
D4
Copyright © 2015 Richtek Technology Corporation. All rights reserved.
DS5070-00 March 2015
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1
1 page  
RT5070
Absolute Maximum Ratings (Note 1)
Supply Input Voltage, VIN-------------------------------------------------------------------------------------------0.3V to 30V
Output Voltage LNB, LX and BOOST Pins ---------------------------------------------------------------------0.3V to 30V
Others Pin to GND ----------------------------------------------------------------------------------------------------0.3V to 6V
Power Dissipation, PD @ TA = 25C
SOP-8 (Exposed pad)------------------------------------------------------------------------------------------------3.44W
Package Thermal Resistance (Note 2)
SOP-8 (Exposed pad), JA------------------------------------------------------------------------------------------29C/W
SOP-8 (Exposed pad), JC------------------------------------------------------------------------------------------2C/W
Lead Temperature (Soldering, 10 sec.)--------------------------------------------------------------------------260C
Junction Temperature ------------------------------------------------------------------------------------------------150C
Storage Temperature Range ---------------------------------------------------------------------------------------65C to 150C
ESD Susceptibility (Note 3)
HBM (Human Body Model) -----------------------------------------------------------------------------------------2kV
MM (Machine Model) -------------------------------------------------------------------------------------------------200V
Recommended Operating Conditions (Note 4)
Supply Input Voltage -------------------------------------------------------------------------------------------------8V to 16V
Ambient Temperature Range---------------------------------------------------------------------------------------40C to 85C
Junction Temperature Range --------------------------------------------------------------------------------------40C to 125C
Electrical Characteristics
(VIN (typ.) = 12V, VIN = 8V to 16V, TA = 25C, unless otherwise specified)
Parameter
Symbol
Test Conditions
Min Typ Max Unit
General
LNB Output Accuracy,
Load and Line Regulation
ERR
Relative to selected VLNB target level,
ILOAD = 0 to 450mA
-3
--
3
%
Supply Current
IIN_OFF
IIN_ON
EN = 0, LNB output disabled
EN = 1, VLNB = 18.3V, Tone = 0V
-- 0.3 0.5
mA
-- 10 18
Boost Switch On
Resistance
Switching Frequency
RDS(ON)
fSW
ILOAD = 450mA
-- 150 300 m
600 700 800 kHz
Switch Current Limit
Linear Regulator Voltage
Drop
ILIMSW
VDROP
Output Voltage Rise Time TR_LNB
Output Voltage Pull-Down
Time
TF_LNB
Ripple and Noise on LNB
Output
VRIP_PP
VIN = 10V, VOUT = 20.5V
VBOOST-VLNB, ILOAD = 450mA
For VLNB = 13.3V18.3V,
CTCA P= 100nF, ILOAD = 450mA
For VLNB = 18.3V13.3V,
CLOAD = 100nF, ILOAD = 0mA
20MHz Bandwidth Limit (GBD)
-- 3 --
-- 0.85 --
-- 3 10
A
V
ms
-- 3 10 ms
-- 20 -- mVPP
Copyright © 2015 Richtek Technology Corporation. All rights reserved.
DS5070-00 March 2015
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
5
5 Page 
where D is the duty cycle and η is the boost converter
efficiency. Finally, take ESR into consideration, the
overall output ripple voltage can be determined by the
following equation :
VOUT
=
IIN
ESR
D IOUT
COUT fOSC
The output capacitor, COUT, should be selected
accordingly.
Input Current
ΔIL
Inductor Current
ΔVOUT1
Output Current
Time
(1-D)TS
Output Ripple
Voltage (ac)
Time
Figure 1. The Output Ripple Voltage without the
Contribution of ESR
Schottky Diode Selection
Schottky diodes are chosen for their low
forward-voltage drop and fast switching speed.
However, when making a selection, important
parameters such as power dissipation, reverse voltage
rating, and pulsating peak current should all be taken
into consideration. A suitable Schottky diode’s reverse
voltage rating must be greater than the maximum
output voltage and its average current rating must
exceed the average output current. The chosen diode
should also have a sufficiently low leakage current level,
since it increases with temperature.
Under-Voltage Lockout (UVLO)
The UVLO circuit compares the input voltage at VIN
with the UVLO threshold (7.7V rising typically) to
ensure that the input voltage is high enough for reliable
RT5070
operation. The 350mV (typ.) hysteresis prevents supply
transients from causing a shutdown. Once the input
voltage exceeds the UVLO rising threshold, start-up
begins. When the input voltage falls below the UVLO
falling threshold, all IC internal functions will be turned
off by the controller.
Over-Current Protection
The RT5070 features an over-current protection
function to prevent chip damage from high peak
currents. Both the boost converter and the linear
regulator have independent current limit. In the boost
converter, this is achieved through cycle-by-cycle
internal current limit. During the ON-period, the chip
senses the inductor current that is flowing into the LX
pin. The internal NMOS will be turned off if the peak
inductor current reaches the current-limit value of 3A
(typ.).When the linear regulator exceeds 550mA (typ.)
more than 45ms, the LNB output will be disabled.
During this period of time, if the current limit condition
disappears, the OCP will be cleared and the part
restarts. If the part is still in current limit after this time
period, the linear regulator and boost converter will
automatically disable to prevent the part from
overheating.
Short Circuit Protection
If the LNB output is shorted to ground, and more than
45ms, the RT5070 will be disabled 1.8s then enable
automatically.
Over-Temperature Protection
When the junction temperature reaches the critical
temperature (typically 140 oC), the boost converter and
the linear regulator are immediately disabled. When the
junction temperature cools down to a lower
temperature threshold specified, the RT5070 will be
allowed to restart by normal start operation.
LNB Output Voltage
The RT5070 has voltage control function on the LNB
output. This function provides 4 levels for the common
standards and compensation if the cable line has
voltage drop. These voltage levels are defined in table
1. The rise time and fall time of the VLNB is 3mS (typ.).
Copyright © 2015 Richtek Technology Corporation. All rights reserved.
DS5070-00 March 2015
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
11
11 Page | ||
| Páginas | Total 14 Páginas | |
| PDF Descargar | [ Datasheet RT5070.PDF ] | |
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