ZNBG3115Q16TC Diodes Zetex, ZNBG3115Q16TC Datasheet - Page 9

• Manufacturer Part Number: ZNBG3115Q16TC
• Description: IC SW 3BIAS TONE H/V 2.2V 16QSOP
• Manufacturer: Diodes Zetex

Specifications of ZNBG3115Q16TC

• Function: Bias Controller
• Rf Type: LNBs, PMR
• Secondary Attributes: with Polarization Switch and Tone Detection
• Package / Case: 16-QSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

For many LNB applications, tone detection for band switching is required. The ZNBG3115/16 includes all the
circuitry necessary to detect the presence of a 22kHz tone modulated on the supply input to the LNB. The main
elements of the detector are an op-amp, a rectifier/smoother and a comparitor. The op-amp has a pre-set internal
feedback resistor so that just a simple RC network wired to the input gives user defined gain and low frequency
cut filter characteristics. The RC network components also serve two other purposes. The resistor provides
overvoltage protection for the Vpol pin and the capacitor minimises tone interference of the Vpol threshold. The
upper frequency roll-off of the op-amp has been set internally at above 100kHz to allow the amplifier to be used
with other common tone switch frequencies.
The rectifier/smoother/comparitor function is provided by a complex propriety circuit that allows the
ZNBG3115/16 to reliably detect wanted tones whilst ignoring low frequency square wave switch box signals,
DiSEqC™ bursts and supply switching transients common when using DiSEqC-2™ ready set-top boxes. This is
all achieved without the need for any further external components. The threshold of the comparitor is supply
dependent, hence the gain of the preceding op-amp must be adjusted in line with supply voltage. See the table
below for recommended values for 22kHz detection, given for a range of supplies.
Table_1
Note: Optimised for F(tone) = 22kHz.
ISSUE 2 - JUNE 2006
Filter
Components
Cf
Rvpol (R2)
Supply Voltage (Vcc)
5V
4.7nF
2k
6V
4.7nF
1.8k
7V
4.7nF
1.5k
9
8V
10nF
1.3k
9V
10nF
1.1k
ZNBG3115
ZNBG3116
10V
10nF
1.0k