ASI4U Datasheet, PDF (12/70 Pages) Zentrum Mikroelektronik Dresden AG – Universal Actuator-Sensor Interface IC

ASI4U / ASI4U-E / ASI4U-F Datasheet
TRANSMIT
The TRANSMIT block transforms a digital response signal to a correctly shaped send current
signal that is applied to the AS-i bus. Due to the inductive network behavior of the network, the
changing send current induces voltage pulses on the network line that overlay the DC operating
voltage. The voltage pulses must have sin²-wave shapes; therefore the send current shape must
follow the integral of the sin²-wave function.
DIGITAL LOGIC The DIGITAL LOGIC block contains the UART, Main State Machine, EEPROM memory and
other control logic. EEPROM write access and other I/O operations of the Main State Machine
are supported in Slave Mode only (see description of general IC operational modes below). In
Master Mode, the IC is basically equivalent to a physical layer transceiver.
If Slave Mode is activated, the UART demodulates the received telegrams, verifies telegram
syntax and timing, and controls a register interface to the Main State Machine. After reception of
a correct telegram, the UART generates appropriate Receive Strobe signals that tell the Main
State Machine to start further processing. The Main State Machine decodes the telegram
information and starts respective I/O processes or EEPROM access. A second register interface
is used to send data back to the UART for construction of a telegram response. The UART
modulates the response data into a Manchester-II-coded bit stream that is used to control the
TRANSMIT unit.
ELECTRONIC INDUCTOR The ELECTRONIC INDUCTOR block is basically a gyrator circuit. It provides an
inductive behavior between the IC’s UIN and UOUT pins while the inductance is controlled by the
capacitor on the CAP pin. The inductor decouples the power regulator of the IC as well as the
external load circuit from the AS-i bus, and this prevents cross talk or switching noise from
disturbing the telegram communication on the bus.
The AS-Interface Complete Specification V3.0 describes the input impedance behavior of a slave
module by an equivalent circuit that consists of a resistance (R), an inductance (L), and a
capacitance (C) in parallel. For example, a slave module in Extended Address Mode must have
R > 13.5kΩ, L > 13.5mH and C < 50pF. The electronic inductor of the ASI4U/ASI4U-E/ASI4U-F
delivers values that are well within the required ranges for output currents up to 55mA. More
detailed parameters can be found in section 4.18.2.
The electronic inductor requires an external capacitor of at least 10µF at the UOUT pin for
stability.
POWER SUPPLY The POWER SUPPLY block consists of a bandgap-referenced 5V regulator and other
reverence voltage and bias current generators for internal use. The 5V regulator requires an
external capacitor at pin U5R of at least 1µF for stability. It can source up to 4mA for external use;
however, the power dissipation and the resulting device heating become a major concern if too
much current is drawn from the regulator.
OSCILLATOR The OSCILLATOR block supports direct connection to 8.000 MHz or 16.000 MHz crystals with a
dedicated load capacity of 12pF and parasitic pin capacities of up to 8pF. The IC automatically
detects the oscillation frequency of the connected crystal and controls the internal clock generator
circuit accordingly.
© 2016 Integrated Device Technology, Inc.
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January 26, 2016