Configurable and customizable mixed-signal solution for motion and power management in printers, scanners, POS and other applications
(Top News, 29 Nov 2007 )
S.A.B.Re (structured architecture of bridges and regulators) represents a new concept in the motion and power supply ICs.
STMicroelectronics’ aim in defining S.A.B.Re specifications was to offer the customer an IC with a wide number of features that can be configured and customized for various applications: motor drivers, regulators, high-precision A/D converters, operational amplifiers, and many other digital or analog circuits – a mixed-signal full system on chip (SoC).
Its physical layout can also be quickly reshaped in order to release a device family able to address both high-power and high-voltage needs.
The S.A.B.Re IC has been primarily developed for motion and power-supply management in printer applications. However, due to its immense flexibility, S.A.B.Re can address any high-power, high-voltage analog and motor application across the industrial segment.
A key advantage over existing motor drivers and switching regulators is that the S.A.B.Re IC manages the whole power section of the application with specific programmable power-up routines.
The device can be configured by programming the IC via the serial interface; the regulator start-up sequence is defined by configuring the GPIO inputs; a deeper customization can be obtained by ST through metal layers in order to set different functions.
The key features of this device are integrated power-up sequencing, a supervisory function with fault signalling and reset management and very low and optimized power dissipation.
S.A.B.Re also has an internal on/off button handler that is able to turn on the IC itself from its sleep mode, that is, the system regulator turns on the whole application. This feature is really important and innovative since the device can be put into sleep mode (power off) by the SoC. In this case, every circuit of the system is off except the function to be activated by a wake-up signal (on button pushed).
This functionality is helpful to get effective management of the application power consumption without the need for any external circuitry.
If used as a system power supply manager, S.A.B.Re can turn off all the power supplies, so reducing the system power consumption down to a very small value (around 35 mW).
This allows the system to meet the requirements of energy efficiency programs such as Energy Star in the United States.
Power-up routines define the IC operating modes (between four possible settings: basic, single, master and slave), the number of regulators of the application architecture, their type (system regulator or not) and their switch-on sequence.
Basic mode has just one pre-defined start-up sequence, while the other 3 modes provide up to 6 predefined regulator start-up sequences on top of the programmable user selection. Master and slave mode have to be selected when two or more ICs are used on the same application board.
The main components of the S.A.B.Re IC are four configurable bridges that can act as four DC motor drivers, or two DC motor drivers and one stepper motor driver, but that can also function as switching regulators or battery charger. Additional components are a variable-voltage buck switching regulator, a switching regulator controller, a linear regulator, a multi-channel configurable 9-bit A/D converter, two operational amplifiers, a bidirectional serial interface and several general-purpose I/Os.
Each of the four H bridges is composed of two independent half bridges, and is protected against: over-current, over-temperature and short circuit to ground, to supply and across the load.
The stepper mode is configured with bridges 3 and 4, and has an internal sequencer with up to 6 operating modes, from full-step to micro-stepping functionality, programmable mixed decay and sinusoidal DACs.
Each H bridge can drive a DC motor with an internal and dedicated PWM programmable signal. S.A.B.Re provides up to 7 PWM signals (3 of them can be externally available through the GPIOs).
A digital encoder input can be managed by the GPIOs and internal blocks (9-bit A/D converter, digital comparators and interrupt controller).
As well as the motor-driver functionalities, the bridges can be configured by user settings for several additional modes.
H bridges 1 and 2 have the same design architecture and can be paralleled to act as a “Super DC” (it is DC driver with output resistance divided by half, enhancing its current capabilities). They can also work as half bridges (up to 4 or in parallel) and as switches (single or in parallel).
H bridges 3 and 4, on top of the configurations offered by bridges 1 and 2 that are always available, offer the possibility to act as two buck regulators (or one super buck with bridges in parallel), or as a switching regulator I-V controller for battery charger applications (only bridge 4).
Other configurable S.A.B.Re components are: one variable buck regulator (in addition to the one that can be implemented with one of the bridges, described above), one switching regulator controller (able to drive an external FET), and one linear regulator. All these regulators can be programmed by internal register settings or with an external DAC, and are protected against over-currents.
Under specific business conditions, a metal layer customization is another possibility for customers to adapt S.A.B.Re to their needs.
The logic portion can be rerouted to obtain specific digital functions (such as interfaces, or to implement an auxiliary switching regulator control loop, or to access a specific internal signal, as well as many others implementations). The number of available gates depends on the already existing functions that remain unused in the customized product.
All existing analog functions can be configured and interconnected, including with digital functions. In this way, customers can obtain complex IPs, or just a specific behaviour or performance of an existing function.
With the configurable blocks listed above, a user can easily set many chip architectures. Below are some simple use cases:
The first example is the architecture of an inkjet printer with mid-range features. Typically, this printer, used at home, could have three DC motors: one to feed the paper (bridge 2), one to move the carriage (bridge 1), and one to have some auxiliary function (bridge 4) such as an ink pump or paper tray selection.
The needs in terms of regulated voltages is about 5 values, 5 V (half of bridge 3) for a USB host or card reader, the core voltage (half of bridge 3) for the digital SoC, typically 1.8 V, the pen voltage, typically 16 V, the 2.5 V DDR voltage and 3.3 V I/O voltage.
Another use case where a single S.A.B.Re fits all the requirements is a low-cost multi-function inkjet printer application. In this case, the S.A.B.Re motor section is composed of the stepper motor driver (bridge 3 and 4) for the scanner and two DC motors, one to move the paper (bridge 2) and one to move the carriage (bridge 1).
A low-cost printer also requires a minimum set of power supplies, the core voltage for the SoC supply, a 3.3 V voltage for SoC I/Os and the pen voltage, all managed by the voltage-regulator section.
The third use case is a high-end multi-function inkjet printer. In this application, the motors usually require more current, and “Super DC” drivers (made by paralleling two H bridges) are needed. Moreover, an additional stepper motor might be necessary for maintenance service of the head.
In this case, with two S.A.B.Re ICs on the same board, one is set as master and the other as slave.
S.A.B.Re represents a first-of-its-kind solution with a complete set of analog functions for motion and power-management applications.
In addition its technical features, S.A.B.Re introduces a new marketing concept. This is to provide the user with a multi-purpose mixed signal device able to shorten and simplify the supply chain once mass production is achieved. Thanks to its high flexibility, the device can be used in several applications and platforms with just different firmware settings and external components and connections. This possibility reduces time and effort in managing effective bill-of-material procedures, reducing stock effects.
S.A.B.Re can also replace several components with a single chip, reducing the overall bill-of-material cost (benchmark analysis has indicated up to 20% saving in BOM).
Customers’ engineers with experience of its flexibility and configurability to different application requirements can quickly adapt it to new projects, optimizing time-to-market product development.
S.A.B.Re is supported by a dedicated development kit, including application board, PC interface, software and the related user manual. The kit helps evaluate the functionalities of S.A.B.Re for different device configurations. It allows the user to simulate power and reset management, the measurement system, power dissipation, and the various power-up sequences provided by S.A.B.Re.
To summarize, S.A.B.Re is a high-potential product enabling customers to get a highly configurable and customizable device that offers the flexibility of a dedicated product at a fraction of the time and cost required by a full-custom design approach.
Author’s Information
Mauro Stefanone, born on March 23 1967 in Pavia, is a Product Marketing Manager at STMicroelectronics. He works on Mixed signal devices and Customizable SoC, mainly for Printer applications. He earned his Electronic Engineering degree in 1992 at University of Pavia and he had advanced study in marketing at SDA Bocconi.
Captions
S.A.B.Re block diagram
Mid-end inkjet printer: motor and power management S.A.B.Re solution
Low-end multi-function inkjet printer: motor and power management S.A.B.Re solution
High-end multi-function inkjet printer: motor and power management S.A.B.Re solution
