|
|
PDF ZNBG3210Q20 Data sheet ( Hoja de datos )
| Número de pieza | ZNBG3210Q20 | |
| Descripción | FET BIAS CONTROLLER WITH POLARISATION SWITCH AND TONE DETECTION | |
| Fabricantes | Zetex Semiconductors | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de ZNBG3210Q20 (archivo pdf) en la parte inferior de esta página. Total 16 Páginas | ||
|
No Preview Available !
FET BIAS CONTROLLER WITH POLARISATION ZNBG3210
SWITCH AND TONE DETECTION
ZNBG3211
ISSUE 2 - FEBRUARY 2000
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 -3 volts, can also be used to
supply other external circuits.
The ZNBG3210/11 includes bias circuits to
drive up to three external FETs. A control
input to the device selects either one of two
FETs as operational using 0V gate switching
methodology, the third FET is permanently
active. This feature is particularly used as an
LNB polarisation switch. Also specific to LNB
applications is the enhanced 22kHz tone
detection and logic output feature which is
used to enable high and low band frequency
switching. The detector has been specifically
designed to reject inerference such as low
frequency signals and DiSEqC tone bursts
- without the use of additional external
components.
Drain current setting of the ZNBG3210/11 is
user selectable over the range 0 to 15mA, this
FEATURES
• 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 -
supporting zero volt gate switching
topology.
• 22kHz tone detection for band switching
• Compliant with ASTRA control
specifications
• QSOP surface mount package
is achieved with the addition of a single
resistor. The series also offers the choice of
FET drain voltage, the 3210 gives 2.2 volts
drain whilst the 3211 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.
In order 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. 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 ZNBG3210/11 are available in QSOP20
for the minimum in device size. Device
operating temperature is -40 to 70°C to suit
a wide range of environmental conditions.
APPLICATIONS
• Satellite receiver LNBs
• Private mobile radio (PMR)
• Cellular telephones
67-1
1 page  
TEST CIRCUIT 1
ZNBG3210
ZNBG3211
TEST CIRCUIT 2
V2 Characteristics
Type
AC source
Frequency 22kHz
Voltage
350mV p/p enabled
100mV p/p disabled
V2 Characteristics
Type
AC source
Frequency 22kHz
Voltage
350mV p/p enabled
100mV p/p disabled
67-5
5 Page 
APPLICATIONS CIRCUIT
ZNBG3210
ZNBG3211
APPLICATIONS INFORMATION
The above is a partial application circuit for the ZNBG series showing all external components
required for appropriate biasing. The bias circuits are unconditionally stable over the full
temperature range with the associated FETs and gate and drain capacitors in circuit.
Capacitors CD and CG ensure that residual power supply and substrate generator noise is not
allowed to affect other external circuits which may be sensitive to RF interference. They also
serve to suppress any potential RF feedthrough between stages via the ZNBG device. These
capacitors are required for all stages used. Values of 10nF and 4.7nF respectively are
recommended however this is design dependent and any value between 1nF and 100nF could
be used.
The capacitors CNB and CSUB are an integral part of the ZNBGs negative supply generator. The
negative bias voltage is generated on-chip using an internal oscillator. The required value of
capacitors CNB and CSUB is 47nF. This generator produces a low current supply of approximately
-3 volts. Although this generator is intended purely to bias the external FETs, it can be used to
power other external circuits via the CSUB pin.
Resistor RCAL sets the drain current at which all external FETs are operated. If any bias control
circuit is not required, its related drain and gate connections may be left open circuit without
affecting the operation of the remaining bias circuits.
The ZNBG devices have been designed to protect the external FETs from adverse operating
conditions. With a JFET connected to any bias circuit, the gate output voltage of the bias circuit
can not exceed the range -3.5V to 1V under any conditions, including powerup and powerdown
transients. Should the negative bias generator be shorted or overloaded so that the drain current
of the external FETs can no longer be controlled, the drain supply to FETs is shut down to avoid
damage to the FETs by excessive drain current.
67-11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet ZNBG3210Q20.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| ZNBG3210Q20 | FET BIAS CONTROLLER WITH POLARISATION SWITCH AND TONE DETECTION | Zetex Semiconductors |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |