ISL9491 Datasheet, PDF (1/13 Pages) Intersil Corporation – LNB Power Supply and Control for Satellite Set-Top Box

Single Output LNB Supply Voltage Regulator for
Satellite Set-Top Box Applications
ISL9491, ISL9491A
Features
These devices are designed for supplying power and
control signals from advanced satellite set-top box (STB)
modules to the low noise blocks (LNBs) of single antenna
ports. Each device consists of a current-mode boost
converter and a low-noise linear regulator along with the
circuitry required for tone injection and pin controllable
interface. The device makes the total LNB supply design
simple, efficient and compact with low external
component count.
The current-mode boost converters provide the linear
regulator with input voltage that is set to the voltage at
the VOUT pin plus a minimal drop to insure minimum
power dissipation across the internal LDO. This maintains
constant voltage drop across the linear pass element
while permitting adequate voltage range for tone
injection.
The final regulated output voltage is available at the
cathode of the back diode to support the operation of an
antenna port for a single tuner. The outputs can be set to
various voltage level for the desired polarization
reception by means of the logic presented to the VSET0
and VSET1 pins. An EN pin is to be driven high to enable
the outputs for the PWM and linear combination; setting
EN low disables the output, forcing a shutdown mode.
The external modulation input (EXTM) can accept a tone
modulated DiSEqC command and transfer it
symmetrically to the output to meet DiSEqC 1.x protocol.
An external DiSEqC tank circuit can also be implemented
to support DiSEqC 2.x.
Ordering Information
PART
NUMBER
(Note)
PART
MARKING
TEMP.
RANGE
(°C)
PACKAGE PKG.
(Pb-free) DWG. #
ISL9491ERZ* 94 91ERZ -20 to +85 16 Ld QFN L16.4x4
ISL9491AERZ* 94 91AERZ -20 to +85 16 Ld QFN L16.4x4
*Add “-T” suffix for tape and reel. Please refer to TB347 for
details on reel specifications.
NOTE: These Intersil Pb-free plastic packaged products employ
special Pb-free material sets, molding compounds/die attach
materials, and 100% matte tin plate plus anneal (e3
termination finish, which is RoHS compliant and compatible with
both SnPb and Pb-free soldering operations). Intersil Pb-free
products are MSL classified at Pb-free peak reflow temperatures
that meet or exceed the Pb-free requirements of IPC/JEDEC J
STD-020.
• Single Chip Power Solution
- Operation for 1-Tuner/1-Dish Applications
• Switch-Mode Power Converter for Lowest Dissipation
- Boost PWMs with >92% Efficiency
- Pin Controllable Enable and Output
• 2.5V/3.3V/5V Logic Compatible
• FAULT Signal
• DIRECTV SWM Compliant
• VSET Pin to Toggle between Vertical and Horizontal
Polarizations
• External Tone Input
• Internal Overcurrent and Over-Temperature
Protection
• Pb-Free (ROHs Compliant)
Applications
• LNB Power Supply and Control for Satellite Set-Top
Box
Pin Configuration
ISL9491, ISL9491A
(16 LD QFN)
TOP VIEW
16 15 14 13
VCC 1
12 ILIMIT
CS 2
11 TCAP
PGND 3
10 VSET1
GATE 4
9 VSET0
5 678
October 13, 2009
FN6531.0
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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