Diodes ZLNB254 User Manual
A
f
ZLNB254
Dual DiSEqC™ Interface IC
SUMMARY
The ZLNB254 is a dual channel DiSEqC™ interface for S atellite Low Noise Blocks
(LNB’s) and distribution systems. Providing two accurate DiSEqC™ detectors the
ZLNB254 converts the DiSEqC™ signals into logic level representations enabling
reliable and easy detection for a microprocessor. Packaged in a small footprint
DFN and only requiring two external components per channel th e complete solution
is cost effective and requires minimal PCB space.
FEATURES
• Dual Channel DiSEqC™ interface
• Reliable and accurate detectors
• High channel isolation
• Compatible with Eutelsat and US specifications
• Simple and easy to design in.
• Outputs compatible with LSTTL and CMOS loads
• Operates over a wide supply voltage
• Temperature compensated
APPLICATIONS
• DiSEqC™ controlled LNB’s
• Satellite distribution systems
• Mono Block LNB’s
• DiSEqC Actuators
• Set-Top Boxes
• Satellite Test Equipment
• AC satellite control signal detection
Product Line o
Diodes Incorporated
2
2
5
5
4
4
ZLNB254
Document number: Ds32002 Rev. 1
1 of 8
www.diodes.com
October 2009
© Diodes Incorporated
DESCRIPTION
The ZLNB254 is a dual DiSEqC™ tone detector IC for
multiple output LNBs, satellite distribution systems,
set-top boxes and DiSEqC™ peripherals. Although
intended for use with 22kHz DiSEqC™ signals, the
ZLNB254 can be used over the frequency range of
10kHz to 60kHz so it can detect standard 22kHz
satellite band control signals as well as regional
variations such as those in Japan.
The minimum of external components are required to
enable this two-channel tone filter and fast envelope
detector. The ZLNB254 is particularly suited to low
signal level, high distortion DiSEqC™ signal detecting
applications.
The ZLNB254 includes circuitry necessary to detect
the presence of a 22kHz tones modulated on the
supply inputs to a LNB or switchbox. The TD outputs
are set low on detection of a valid tone or DiSEqC™
signal when applied to the FIN inputs.
To enable system flexibility user control is given over
the gain and the lower frequency limit of the filter by
using a single external resistor and capacitor per
channel. The higher frequency limit of the filters is set
Pinout Diagram
TDFN2020-6 Top view
1
TD2
2
GND
3
FIN1
6
TD1
5
VCC
4
FIN2
ZLNB254
internally above 60kHz. The remaining detector
circuits utilises no other external components.
The tone detector can be used to sense either
continuous tones or coded tone bursts such as used
in DiSEqC™ and similar control systems. To ensure
system reliability the tone detector rejects unwanted
signals including transients from other parts of the
LNB system without the use of any external
components.
The TD outputs are designed to be compatible with
LSTTL and CMOS loads so can drive a
microcontroller or other logic directly.
To give further protection the resistor which is used to
set the filter gain also provides ESD protection.
The ZNBL254 provides a small simple solution and is
packaged in the TDFN2020-6 surface mount
package.
ZLNB254
Document number: Ds32002 Rev. 1
2 of 8
www.diodes.com
October 2009
© Diodes Incorporated
(1)
ZLNB254
Absolute Maximum Ratings
Supply Voltage -0.6V to +15V
Supply Current 50mA
Power Dissipation 350mW
Operating Temperature Range -40°C to +85°C
Storage Temperature Range -40°C to +125°C
Electrical Characteristics
Measured at Tamb = 25°C, Vcc = 5V unless otherwise specified.
Parameter Conditions Limits
Min Typ Max
Supply Voltage
Operating Range
Supply Current All outputs unloaded, any combination of valid
Tone Detectors
AC Thresh
Switching Delay TD outputs, Test Circuit 2 100 150 us
TD Outputs
Voltage High ITD = -2mA, Test Circuit 1, Tone disabled Vcc-0.5 Vcc-0.2 Vcc V
Voltage Low ITD = 5mA, Test Circuit 1, Tone enabled 0 0.29 0.5 V
Notes: 1. The tone detector threshold is Vcc dependent. See Application section for details.
Test Circuit 1 100 140 200 mVp/p
inputs.
3.0 8 V
0.7 2 mA
Units
ZLNB254
Document number: Ds32002 Rev. 1
3 of 8
www.diodes.com
October 2009
© Diodes Incorporated
Loading...