znbg3115 Zetex Semiconductors plc., znbg3115 Datasheet

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znbg3115

Manufacturer Part Number
znbg3115
Description
Znbg3115 - Fet Bias Controller With Polarization Switch And Tone Detection
Manufacturer
Zetex Semiconductors plc.
Datasheet

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FET BIAS CONTROLLER WITH POLARISATION
SWITCH AND TONE DETECTION
ISSUE 2 - JUNE 2006
DEVICE DESCRIPTION
The ZNBG series of devices are designed to meet the
bias requirements of GaAs and HEMT FETs
commonly used in satellite receiver LNBs, PMR,
cellular telephones etc. with a minimum of external
components.
With the addition of two capacitors and a resistor the
devices provide drain voltage and current control for
three external grounded source FETs, generating
the regulated negative rail required for FET gate
biasing whilst operating from a single supply. This
negative bias, at -2.8 volts, can also be used to
supply other external circuits.
The ZNBG3115/16 includes bias circuits to drive up
to three external FETs. A control input to the device
selects either one of two FETs as operational, the
third FET is permanently active. This feature is
normally used as an LNB polarisation switch. Also
specific to Universal LNB applications is the 22kHz
tone detection and logic output feature which is
used to enable high and low band frequency
switching.
The ZNBG3115/16 has been designed to cope with
DiSEqC™ ready set top boxes and rejects all
transients from channel switching.
FEATURES
ISSUE 2 - JUNE 2006
Provides bias for GaAs and HEMT FETs
Drives up to three FETs
Dynamic FET protection
Drain current set by external resistor
Regulated negative rail generator requires only
2 external capacitors
Choice in drain voltage
Wide supply voltage range
Polarisation switch for LNBs
22kHz tone detection for band switching
Tone detector ignores unwanted signals
Support fr MIMIC, FET and Bipolar local
oscillator devices
Compliant with ASTRA control specifications
QSOP 16 and 20 surface mount packages
1
Drain current setting of the ZNBG3115/16 is user
selectable over the range 0 to 15mA, this is achieved
with addition of a single resistor. The series also offers
the choice of drain voltage to be set for the FETs, the
3115 gives 2.2 volts drain whilst the 3116 gives 2 volts.
These devices are unconditionally stable over the full
working temperature with the FETs in place, subject to
the inclusion of the recommended gate and drain
capacitors. These ensure RF stability and minimal
injected noise.
It is possible to use less than the devices full
complement of FET bias controls, unused drain and gate
connections can be left open circuit without affecting
operation of the remaining bias circuits.
To protect the external FETs the circuits have been
designed to ensure that, under any conditions including
power up/down transients, the gate drive from the bias
circuits cannot exceed the range -3.5V to 1V.
Additionally each stage has its own individual current
limiter. Furthermore if the negative rail experiences a
fault condition, such as overload or short circuit, the
drain supply to the FETs will shut down avoiding
excessive current flow.
The ZNBG3115/16 are available in QSOP16 and QSOP20
for the minimum in device size. Device operating
temperature is -40 to 80°C to suit a wide range of
environmental conditions.
APPLICATIONS
Satellite receiver LNBs
Private mobile radio (PMR)
Cellular telephones
ZNBG3115
ZNBG3116

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znbg3115 Summary of contents

Page 1

... QSOP 16 and 20 surface mount packages ISSUE 2 - JUNE 2006 ZNBG3115 ZNBG3116 Drain current setting of the ZNBG3115/16 is user selectable over the range 0 to 15mA, this is achieved with addition of a single resistor. The series also offers the choice of drain voltage to be set for the FETs, the 3115 gives 2 ...

Page 2

... ZNBG3115 ZNBG3116 ABSOLUTE MAXIMUM RATINGS Supply Voltage -0.6V to 12V Supply Current 100mA Input Voltage (V ) 25V Continuous POL Drain Current (per FET 15mA (set CAL Operating Temperature -40 to 80°C Storage Temperature -50 to 85°C ELECTRICAL CHARACTERISTICS. TEST CONDITIONS (Unless otherwise stated):T amb ...

Page 3

... V =15.5V D1 POL I =10mA, V =15.5V D1 POL I =10mA, V =14V D2 POL I =10mA, V =14V D2 POL I =10mA, V =15.5V D3 POL I =10mA, V =15.5V D3 POL 10V CC T =-40 to +80° =0.5V, V =14V D1 POL V =0.5V, V =15.5V D2 POL 3 ZNBG3115 ZNBG3116 LIMITS UNITS MIN. TYP. MAX. -30 2000 NA -2.5 -2.25 -2.0 V -2.5 -2.25 -2.0 V 0.4 0.75 1.0 V -2.5 -2.25 -2.0 V -2.5 -2.25 -2.0 V 0.4 0.75 1.0 V -3.0 -2.75 -2.5 V 0.4 0.75 1 ...

Page 4

... ZNBG3115 ZNBG3116 SYMBOL PARAMETER TONE DETECTION CHARACTERISTICS V Filter Amplifier OUT 5 Bias Voltage F Input Impedance inz AG Amplifier Gain Threshold T Output Stage Volt. Range LOV Bias Current LOV Output Low LBL Output High LBH Output Low HBL ...

Page 5

... TEST CIRCUIT 1 Note: Same circuit used for QSOP16 option but with adjusted pinout. ISSUE 2 - JUNE 2006 ZNBG3115 ZNBG3116 5 ...

Page 6

... ZNBG3115 ZNBG3116 6 ISSUE 2 - JUNE 2006 ...

Page 7

... The ZNBG devices provide all the bias requirements for external FETs, including the generation of the negative supply required for gate biasing, from the single supply voltage.The diagram above shows a single stage from the ZNBG series. The ZNBG3115/16 contains 3 such stages. The negative rail generator is common to both devices. ...

Page 8

... ZNBG3115 ZNBG3116 The following schematic shows the function of the V Q2 are powered at any one time, their selection is controlled by the input V to the power input of the LNB via a high value (10k) resistor. With the input voltage of the LNB set at or below 14V, FET Q2 will be enabled ...

Page 9

... 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 ...

Page 10

... The bias circuits are unconditionally stable over the full temperature range with the associated FETs and gate and drain capacitors in circuit. To minimise board space the ZNBG3115/3116 is offered in a QSOP16 package. To reduce the pin count Drain 1 and Drain 2 have been internally connected. This is possible because only one of the two bias stages can biased at one time ...

Page 11

... The following block diagram shows the main section of an LNB designed for use with the Astra series of satellites. The ZNBG3115/16 is the core bias and control element of this circuit. The ZNBG provides the negative rail, FET bias control, polarisation switch control, tone detection and band switching with the minimum of external components ...

Page 12

... ZNBG3115 ZNBG3116 APPLICATIONS Local Oscillator Circuits 12 Figure 1 Figure 2 Figure 3 ISSUE 2 - JUNE 2006 ...

Page 13

... QSOP20 ZNBG3116Q20 QSOP20 ISSUE 2 - JUNE 2006 QSOP16 D12 R 2 CAL POL N/C Gnd 6 N/C Cnb1 7 Lov Cnb2 SUB Part Mark ZNBG3115 ZNBG3116 ZNBG3115 ZNBG3116 13 ZNBG3115 ZNBG3116 Rcal 15 Vpol 14 Fin 13 Lov Csub 9 ...

Page 14

... ZNBG3115 ZNBG3116 QSOP16 DIM Millimetres Inches MIN MAX MIN A 4.80 4.98 0.189 B 0.635 0.025 NOM C 0.23 REF 0.009 REF D 0.20 0.30 0.008 E 3.81 3.99 0.15 F 1.35 1.75 0.053 G 0.10 0.25 0.004 J 5.79 6.20 0.228 K 0° 8° 0° Conforms to JEDEC MO-137AB Iss A QSOP20 DIM Millimetres MIN MAX A 8.55 0.196 B 0.635 C 1.47 REF D 0.20 0.012 E 3.81 0.157 F 1.35 0.069 G 0.10 0.01 J 5.79 0.244 K 0° ...

Page 15

... The Company reserves the right to alter without notice the specification, design, price or conditions of supply of any product or service. For the latest product information, log on to www.zetex.com ISSUE 2 - JUNE 2006 ZNBG3115 ZNBG3116 Asia Pacific Corporate Headquarters ...

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