AT1512
Preliminary product Information
FET BIAS CONTROLLER AND TONE DETECTION
Features
•Provides
bias for GaAs and HEMT FETs
•Drives
up to 3 FETs with Dynamic FET
protection
•Regulated
negative rail generator requires only
2 external capacitors
•Drain
current set by external resistor
•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
•SSOP-20
surface mount package
Description
The AT1512 includes bias circuits to drive up to
3 external FETs. A control input to the device
selects either one of two FETs as operational
using 0V gate switching topology, 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
TM
tone bursts
- without the use of additional external
components.
Drain current setting of the AT1512 is user
selectable over the range from 0 to 15mA, this is
achieved with the addition of a single resistor.
The series also offers the choice of FET drain
voltage, the AT1512 gives 2V.
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 AT1512 are available in SSOP20 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
Aimtron reserves the right without notice to change this circuitry and specifications.
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW:http://www.aimtron.com.tw
2005/10/19 REV:1.0
Email:
service@aimtron.com.tw
1
AIMTRON [ AIMTRON TECHNOLOGY ]
