The SHARC ADSP-21489 is one of two new members of the fourth generation of SHARC® Processors that now includes the ADSP-21483, ADSP-21486, ADSP-21487, ADSP-21488, ADSP-21489 and offers increased performance, hardware-based filter accelerators, audio and application-focused peripherals, and new memory configurations capable of supporting the latest surround-sound decoder algorithms. All devices are pin-compatible with each other and completely code-compatible with all prior SHARC Processors. These newest members of the fourth generation SHARC Processor family are based on a single-instruction, multiple-data (SIMD) core, which supports both 32-bit fixed-point and 32-/40-bit floating-point arithmetic formats making them particularly suitable for high-performance audio applications.The ADSP-21489 offers the highest performance–450 MHz/2700 MFLOPs–in an LQFP package within the fourth generation SHARC Processor family. This level of performance makes the ADSP-21489 particularly well suited to address the automotive audio and industrial control segments. In addition to its high core performance, the ADSP-21489 includes additional processing blocks such as FIR, IIR, and FFT accelerators to increase the total performance of the system. There is a new feature called Variable Instruction Set Architecture (VISA) that allows the code size to be decreased by 20% to 30% and increase the memory size availability. The fourth generation DSP allows the ability to connect to external memory by providing a glueless interface to 16-bit wide SDR SDRAMs.Fourth-generation SHARC Processors also integrate application-specific peripherals designed to simplify hardware design, minimize design risks, and ultimately reduce time to market. Grouped together, and broadly named the Digital Applications Interface (DAI), these functional blocks may be connected to each other or to external pins via the software-programmable Signal Routing Unit (SRU). The SRU is an innovative architectural feature that enables complete and flexible routing amongst DAI blocks. Peripherals connected through the SRU include but are not limited to serial ports, IDP, S/PDIF Tx/Rx, and an 8-Channel asynchronous sample rate converter block. The fourth generation SHARC allows data from the serial ports to be directly transferred to external memory by the DMA controller. Other peripherals such as SPI,UART and Two-Wire Interface are routed through a Digital Peripheral Interface (DPI).

The SHARC ADSP-21489 is one of two new members of the fourth generation of SHARC® Processors that now includes the ADSP-21483, ADSP-21486, ADSP-21487, ADSP-21488, ADSP-21489 and offers increased performance, hardware-based filter accelerators, audio and application-focused peripherals, and new memory configurations capable of supporting the latest surround-sound decoder algorithms. All devices are pin-compatible with each other and completely code-compatible with all prior SHARC Processors. These newest members of the fourth generation SHARC Processor family are based on a single-instruction, multiple-data (SIMD) core, which supports both 32-bit fixed-point and 32-/40-bit floating-point arithmetic formats making them particularly suitable for high-performance audio applications.The ADSP-21489 offers the highest performance–450 MHz/2700 MFLOPs–in an LQFP package within the fourth generation SHARC Processor family. This level of performance makes the ADSP-21489 particularly well suited to address the automotive audio and industrial control segments. In addition to its high core performance, the ADSP-21489 includes additional processing blocks such as FIR, IIR, and FFT accelerators to increase the total performance of the system. There is a new feature called Variable Instruction Set Architecture (VISA) that allows the code size to be decreased by 20% to 30% and increase the memory size availability. The fourth generation DSP allows the ability to connect to external memory by providing a glueless interface to 16-bit wide SDR SDRAMs.Fourth-generation SHARC Processors also integrate application-specific peripherals designed to simplify hardware design, minimize design risks, and ultimately reduce time to market. Grouped together, and broadly named the Digital Applications Interface (DAI), these functional blocks may be connected to each other or to external pins via the software-programmable Signal Routing Unit (SRU). The SRU is an innovative architectural feature that enables complete and flexible routing amongst DAI blocks. Peripherals connected through the SRU include but are not limited to serial ports, IDP, S/PDIF Tx/Rx, and an 8-Channel asynchronous sample rate converter block. The fourth generation SHARC allows data from the serial ports to be directly transferred to external memory by the DMA controller. Other peripherals such as SPI,UART and Two-Wire Interface are routed through a Digital Peripheral Interface (DPI).

The BF504 is a low cost member of the Blackfin portfolio of processors. With a 400 MHz core clock speed and a unique peripheral set including two three-phase PWM units, an ADC Control Module, two SPI’s, two SPORT’s, a CAN controller, a PPI, eight general purpose counters and a Removable Storage Interface, the BF504 is feature and cost optimized for compute intensive industrial and general purpose applications that do not require external memory or executable flash. The BF504 is offered in a low cost 12 × 12mm LFCSP package in commercial and industrial temperature grades.

The BF592 is the low cost entry point into the Blackfin portfolio of processors. With core clock speeds of 200 and 400 MHz and a peripheral set including two SPORT’s, a PPI, two SPI’s, four general purpose counters and a factory-programmed Instruction ROM block containing the VDK RTOS and C-runtime libraries, the BF592 is feature and cost optimized for compute intensive industrial, automotive, and general purpose applications that do not require external memory or executable flash. The BF592 is offered in a low cost 9×9mm LFCSP package in commercial and industrial temperature grades as well as automotive qualified. 

The ADuC7019 / ADuC7020 / ADuC7021 / ADuC7022 / ADuC7024 / ADuC7025 / ADuC7026 / ADuC7027 / ADuC7028 / ADuC7029 are fully integrated,1 MSPS, 12-bit data acquisition systems incorporating highperformance multichannel ADCs, 16-bit/32-bit MCUs, andFlash®/EE memory on a single chip.The ADC consists of up to 12 single-ended inputs. An additionalfour inputs are available but are multiplexed with the four DACoutput pins. The four DAC outputs are available only on certainmodels (ADuC7020, ADuC7026, ADuC7028, and ADuC7029).However, in many cases where the DAC outputs are not present,these pins can still be used as additional ADC inputs, giving amaximum of 16 ADC input channels. The ADC can operate insingle-ended or differential input mode. The ADC input voltageis 0 V to VREF. A low drift band gap reference, temperature sensor,and voltage comparator complete the ADC peripheral set.Depending on the part model, up to four buffered voltageoutput DACs are available on-chip. The DAC output range isprogrammable to one of three voltage ranges.The devices operate from an on-chip oscillator and a PLLgenerating an internal high frequency clock of 41.78 MHz(UCLK). This clock is routed through a programmable clockdivider from which the MCU core clock operating frequencyis generated. The microcontroller core is an ARM7TDMI®,16-bit/32-bit RISC machine, which offers up to 41 MIPS peakperformance. Eight kilobytes of SRAM and 62 kilobytes ofnonvolatile Flash/EE memory are provided on-chip. TheARM7TDMI core views all memory and registers as a singlelinear array.On-chip factory firmware supports in-circuit serial downloadvia the UART or I2C serial interface port; nonintrusive emulationis also supported via the JTAG interface. These features areincorporated into a low cost QuickStart™ development systemsupporting this MicroConverter® family.The parts operate from 2.7 V to 3.6 V and are specified over anindustrial temperature range of −40°C to +125°C. Whenoperating at 41.78 MHz, the power dissipation is typically120 mW. The ADuC7019 / ADuC7020 / ADuC7021 / ADuC7022 / ADuC7024 / ADuC7025 / ADuC7026 / ADuC7027 / ADuC7028 / ADuC7029 areavailable in a variety of memory models and packages (seeOrdering Guide).APPLICATIONS Industrial control and automation systems Smart sensors, precision instrumentation Base station systems, optical networking

The ADuM2210 / ADuM22111 are 2-channel digital isolators based on Analog Devices, Inc., iCoupler® technology. Combining high speed CMOS and monolithic air core transformer technology, these isolation components provide outstanding performance characteristics that are superior to alternatives such as optocoupler devices.By avoiding the use of LEDs and photodiodes, iCoupler devices remove the design difficulties commonly associated with optocouplers.Typical optocoupler concerns regarding uncertain current transfer ratios, nonlinear transfer functions, and temperature and lifetime effects are eliminated with the simple iCoupler digital interfaces and stable performance characteristics. The need for external drivers and other discrete components is eliminated with these iCoupler products. Furthermore, iCoupler devices run atone-tenth to one-sixth the power of optocouplers at comparable signal data rates.The ADuM2210 / ADuM2211 isolators provide two independent isolation channels in a variety of channel configurations and data rates. They operate with the supply voltage of either side ranging from 3.0 V to 5.5 V, providing compatibility with lower voltage systems as well as enabling voltage translation functionality across the isolation barrier. The ADuM2210W and ADuM2211W are automotive grade versions.Similar to the ADuM3200 / ADuM3201 isolators, the ADuM2210 / ADuM2211 isolators contain various circuit and layout enhancements to provide increased capability relative to system-level IEC 61000-4-x testing (ESD, burst, and surge). The precise capability in these tests for either the ADuM3200 / ADuM3201 or ADuM2210 / ADuM2211 products is strongly determined by the design and layout of the user’s board or module. For more information, see the AN-793 Application Note, ESD/Latch-Up Considerations with iCoupler Isolation Products.APPLICATIONS General-purpose, high voltage, multichannel isolation Medical equipment Power supplies RS-232/RS-422/RS-485 transceiver isolation  Hybrid electric vehicles, battery monitors, and motor drives

The ADuM2210 / ADuM22111 are 2-channel digital isolators based on Analog Devices, Inc., iCoupler® technology. Combining high speed CMOS and monolithic air core transformer technology, these isolation components provide outstanding performance characteristics that are superior to alternatives such as optocoupler devices.By avoiding the use of LEDs and photodiodes, iCoupler devices remove the design difficulties commonly associated with optocouplers.Typical optocoupler concerns regarding uncertain current transfer ratios, nonlinear transfer functions, and temperature and lifetime effects are eliminated with the simple iCoupler digital interfaces and stable performance characteristics. The need for external drivers and other discrete components is eliminated with these iCoupler products. Furthermore, iCoupler devices run atone-tenth to one-sixth the power of optocouplers at comparable signal data rates.The ADuM2210 / ADuM2211 isolators provide two independent isolation channels in a variety of channel configurations and data rates. They operate with the supply voltage of either side ranging from 3.0 V to 5.5 V, providing compatibility with lower voltage systems as well as enabling voltage translation functionality across the isolation barrier. The ADuM2210W and ADuM2211W are automotive grade versions.Similar to the ADuM3200 / ADuM3201 isolators, the ADuM2210/ADuM2211 isolators contain various circuit and layout enhancements to provide increased capability relative to system-level IEC 61000-4-x testing (ESD, burst, and surge). The precise capability in these tests for either the ADuM3200 / ADuM3201 or ADuM2210 / ADuM2211 products is strongly determined by the design and layout of the user’s board or module. For more information, see the AN-793 Application Note, ESD/Latch-Up Considerations with iCoupler Isolation Products.APPLICATIONS General-purpose, high voltage, multichannel isolation Medical equipment Power supplies RS-232/RS-422/RS-485 transceiver isolation  Hybrid electric vehicles, battery monitors, and motor drives

The ADuM2210 / ADuM22111 are 2-channel digital isolators based on Analog Devices, Inc., iCoupler® technology. Combining high speed CMOS and monolithic air core transformer technology, these isolation components provide outstanding performance characteristics that are superior to alternatives such as optocoupler devices.By avoiding the use of LEDs and photodiodes, iCoupler devices remove the design difficulties commonly associated with optocouplers.Typical optocoupler concerns regarding uncertain current transfer ratios, nonlinear transfer functions, and temperature and lifetime effects are eliminated with the simple iCoupler digital interfaces and stable performance characteristics. The need for external drivers and other discrete components is eliminated with these iCoupler products. Furthermore, iCoupler devices run atone-tenth to one-sixth the power of optocouplers at comparable signal data rates.The ADuM2210 / ADuM2211 isolators provide two independent isolation channels in a variety of channel configurations and data rates. They operate with the supply voltage of either side ranging from 3.0 V to 5.5 V, providing compatibility with lower voltage systems as well as enabling voltage translation functionality across the isolation barrier. The ADuM2210W and ADuM2211W are automotive grade versions.Similar to the ADuM3200 / ADuM3201 isolators, the ADuM2210/ADuM2211 isolators contain various circuit and layout enhancements to provide increased capability relative to system-level IEC 61000-4-x testing (ESD, burst, and surge). The precise capability in these tests for either the ADuM3200 / ADuM3201 or ADuM2210 / ADuM2211 products is strongly determined by the design and layout of the user’s board or module. For more information, see the AN-793 Application Note, ESD/Latch-Up Considerations with iCoupler Isolation Products.APPLICATIONS General-purpose, high voltage, multichannel isolation Medical equipment Power supplies RS-232/RS-422/RS-485 transceiver isolation  Hybrid electric vehicles, battery monitors, and motor drives

The ADuM3160 is a USB port isolator, based on Analog Devices, Inc., iCoupler® technology. Combining high speed CMOS and monolithic air core transformer technology, this isolation component provides outstanding performance characteristics and is easily integrated with low and full speed USB-compatible peripheral devices.Many microcontrollers implement USB so that it presents only the D+ and D− lines to external pins. This is desirable in many cases because it minimizes external components and simplifies the design; however, this presents particular challenges when isolation is required. Because the USB lines must switch between actively driving D+/D− and allowing external resistors to set the state of the bus, the ADuM3160 provides mechanisms for detecting the direction of data flow and control over the state of the output buffers. Data direction is determined on a packet-by-packet basis.The ADuM3160 uses the edge detection based iCoupler technology in conjunction with internal logic to implement a transparent, easily configured, upstream-facing port isolator. Isolating the upstream port provides several advantages in simplicity, power management, and robust operation.The isolator has propagation delay comparable to that of a standard hub and cable. It operates with the supply voltage on either side ranging from 3.0 V to 5.5 V, allowing connection directly to VBUSx by internally regulating the voltage to the signaling level. The ADuM3160 provides isolated control of the pull-up resistor to allow the peripheral to control connection timing. The device draws low enough idle current that a suspend state is not required. A 5 kV, reinforced insulation version, the ADuM4160, is available.APPLICATIONS USB peripheral isolation Isolated USB hub

The ADuM3220/ADuM32211 are isolated, 4A dual-channel gate drivers based on the Analog Devices, Inc., iCoupler®technology. Combining high speed CMOS and monolithic transformer technology, these isolation components provide outstandingperformance characteristics superior to the alternatives, such as the combination of pulse transformers and gate drivers.The ADuM3220/ADuM3221 provide digital isolation in two independent isolation channels. They have a maximum propagationdelay of 60 ns and 5 ns channel-to-channel matching. In comparison to gate drivers that employ high voltage level translationmethodologies, the ADuM3220/ADuM3221 offer the benefit of true, galvanic isolation between the input and each output,enabling voltage translation across the isolation barrier. The ADuM3220 has shoot-through protection logic, which preventsboth outputs from being on at the same time, whereas the ADuM3221 allows both outputs to be on at the same time. Both partsoffer a default output low characteristic as required for gate drive applications.The ADuM3220/ADuM3221 operate with an input supply voltage ranging from 3.0 V to 5.5 V, providing compatibility with lowervoltage systems. The outputs of the ADuM3220A/ADuM3221A can be operated at supply voltages from 4.5 V to 18 V. The outputs ofthe ADuM3220B/ADuM3221B can be operated at supply voltages from 7.6 V to 18 V.The junction temperature of the ADuM3220/ADuM3221 is specified from −40°C to +125°C.Applications Isolated synchronous dc-to-dc converters MOSFET/IGBT gate drivers

The ADuM3470 / ADuM3471/ADuM3472 / ADuM3473 / ADuM3474 devicesare quad-channel, digital isolators withan integrated PWM controller and transformer driver for anisolated DC/DC converter. Based on the Analog Devices, Inc.,iCoupler® technology, the DC/DC converter provides up to 2 Wof regulated, isolated power at 3.3 V to 24 V from a 5.0 V inputsupply or from a 3.3 V supply. This eliminates the need for aseparate, isolated DC/DC converter in 2 W isolated designs.The iCoupler chip-scale transformer technology is used to isolatethe logic signals, and the integrated transformer driver withisolated secondary side control provides higher efficiency for theisolated DC/DC converter. The result is a small form factor, totalisolation solution.The ADuM347x isolators provide four independent isolationchannels in a variety of channel configurations and data rates.APPLICATIONS RS-232/RS-422/RS-485 transceivers Industrial field bus isolation Power supply startup bias and gate drives Isolated sensor interfaces Process controls Automotive

The ADuM3470 / ADuM3471 / ADuM3472 / ADuM3473 / ADuM3474 devicesare quad-channel, digital isolators withan integrated PWM controller and transformer driver for anisolated DC/DC converter. Based on the Analog Devices, Inc.,iCoupler® technology, the DC/DC converter provides up to 2 Wof regulated, isolated power at 3.3 V to 24 V from a 5.0 V inputsupply or from a 3.3 V supply. This eliminates the need for aseparate, isolated DC/DC converter in 2 W isolated designs.The iCoupler chip-scale transformer technology is used to isolatethe logic signals, and the integrated transformer driver withisolated secondary side control provides higher efficiency for theisolated DC/DC converter. The result is a small form factor, totalisolation solution.The ADuM347x isolators provide four independent isolationchannels in a variety of channel configurations and data rates.APPLICATIONS RS-232/RS-422/RS-485 transceivers Industrial field bus isolation Power supply startup bias and gate drives Isolated sensor interfaces Process controls

The ADuM3470 / ADuM3471 / ADuM3472 / ADuM3473 / ADuM3474 devicesare quad-channel, digital isolators withan integrated PWM controller and transformer driver for anisolated DC/DC converter. Based on the Analog Devices, Inc.,iCoupler® technology, the DC/DC converter provides up to 2 Wof regulated, isolated power at 3.3 V to 24 V from a 5.0 V inputsupply or from a 3.3 V supply. This eliminates the need for aseparate, isolated DC/DC converter in 2 W isolated designs.The iCoupler chip-scale transformer technology is used to isolatethe logic signals, and the integrated transformer driver withisolated secondary side control provides higher efficiency for theisolated DC/DC converter. The result is a small form factor, totalisolation solution.The ADuM347x isolators provide four independent isolationchannels in a variety of channel configurations and data rates.APPLICATIONS RS-232/RS-422/RS-485 transceivers Industrial field bus isolation Power supply startup bias and gate drives Isolated sensor interfaces Process controls

The ADuM4160 is a USB port isolator, based on Analog Devices, Inc., iCoupler® technology. Combining high speed CMOS and monolithic air core transformer technology, these isolation components provide outstanding performance characteristics and are easily integrated with low and full speed USB-compatible peripheral devices.Many microcontrollers implement USB so that it presents only the D+ and D− lines to external pins. This is desirable in many cases because it minimizes external components and simplifies the design; however, this presents particular challenges when isolation is required. USB lines must automatically switch between actively driving D+/D−, receiving data, and allowing external resistors to set the idle state of the bus. The ADuM4160 provides mechanisms for detecting the direction of data flow and control over the state of the output buffers. Data direction is determined on a packet-by-packet basis.The ADuM4160 uses the edge detection based iCoupler technology in conjunction with internal logic to implement a transparent, easily configured, upstream facing port isolator. Isolating an upstream facing port provides several advantages in simplicity, power management, and robust operation.The isolator has propagation delay comparable to that of a standard hub and cable. It operates with the supply voltage on either side ranging from 3.1 V to 5.5 V, allowing connection directly to VBUS by internally regulating the voltage to the signaling level. The ADuM4160 provides isolated control of the pull-up resistor to allow the peripheral to control connection timing. The device has a low idle current; a suspend mode is not required.APPLICATIONS USB peripheral isolation Isolated USB hub Medical applications

The ADuM440x are 4-channel digital isolators based on the Analog Devices, Inc., iCoupler® technology. Combining high speed CMOS and monolithic air core transformer technology, these isolation components provide outstanding performance characteristics that are superior to the alternatives, such as optocoupler devices and other integrated couplers.The ADuM440x isolators provide four independent isolation channels in a variety of channel configurations and data rates (see the Ordering Guide). All models operate with the supply voltage on either side ranging from 3.0 V to 5.5 V, providing compatibility with lower voltage systems as well as enabling a voltage translation functionality across the isolation barrier. The ADuM440x isolators have a patented refresh feature that ensures dc correctness in the absence of input logic transitions and during power-up/power-down conditions.This family of isolators, like many Analog Devices isolators, offers very low power consumption, consuming one-tenth to one-sixth the power of comparable isolators at comparable data rates up to 10 Mbps. All models of the ADuM440x provide low pulse width distortion (

The ADuM440x are 4-channel digital isolators based on the Analog Devices, Inc., iCoupler® technology. Combining high speed CMOS and monolithic air core transformer technology, these isolation components provide outstanding performance characteristics that are superior to the alternatives, such as optocoupler devices and other integrated couplers.The ADuM440x isolators provide four independent isolation channels in a variety of channel configurations and data rates (see the Ordering Guide). All models operate with the supply voltage on either side ranging from 3.0 V to 5.5 V, providing compatibility with lower voltage systems as well as enabling a voltage translation functionality across the isolation barrier. The ADuM440x isolators have a patented refresh feature that ensures dc correctness in the absence of input logic transitions and during power-up/power-down conditions.This family of isolators, like many Analog Devices isolators, offers very low power consumption, consuming one-tenth to one-sixth the power of comparable isolators at comparable data rates up to 10 Mbps. All models of the ADuM440x provide low pulse width distortion (

The ADuM440x are 4-channel digital isolators based on the Analog Devices, Inc., iCoupler® technology. Combining high speed CMOS and monolithic air core transformer technology, these isolation components provide outstanding performance characteristics that are superior to the alternatives, such as optocoupler devices and other integrated couplers.The ADuM440x isolators provide four independent isolation channels in a variety of channel configurations and data rates (see the Ordering Guide). All models operate with the supply voltage on either side ranging from 3.0 V to 5.5 V, providing compatibility with lower voltage systems as well as enabling a voltage translation functionality across the isolation barrier. The ADuM440x isolators have a patented refresh feature that ensures dc correctness in the absence of input logic transitions and during power-up/power-down conditions.This family of isolators, like many Analog Devices isolators, offers very low power consumption, consuming one-tenth to one-sixth the power of comparable isolators at comparable data rates up to 10 Mbps. All models of the ADuM440x provide low pulse width distortion (

The ADuM440x are 4-channel digital isolators based on the Analog Devices, Inc., iCoupler® technology. Combining high speed CMOS and monolithic air core transformer technology, these isolation components provide outstanding performance characteristics that are superior to the alternatives, such as optocoupler devices and other integrated couplers.The ADuM440x isolators provide four independent isolation channels in a variety of channel configurations and data rates (see the Ordering Guide). All models operate with the supply voltage on either side ranging from 3.0 V to 5.5 V, providing compatibility with lower voltage systems as well as enabling a voltage translation functionality across the isolation barrier. The ADuM440x isolators have a patented refresh feature that ensures dc correctness in the absence of input logic transitions and during power-up/power-down conditions.This family of isolators, like many Analog Devices isolators, offers very low power consumption, consuming one-tenth to one-sixth the power of comparable isolators at comparable data rates up to 10 Mbps. All models of the ADuM440x provide low pulse width distortion (

The ADuM440x are 4-channel digital isolators based on the Analog Devices, Inc., iCoupler® technology. Combining high speed CMOS and monolithic air core transformer technology, these isolation components provide outstanding performance characteristics that are superior to the alternatives, such as optocoupler devices and other integrated couplers.The ADuM440x isolators provide four independent isolation channels in a variety of channel configurations and data rates (see the Ordering Guide). All models operate with the supply voltage on either side ranging from 3.0 V to 5.5 V, providing compatibility with lower voltage systems as well as enabling a voltage translation functionality across the isolation barrier. The ADuM440x isolators have a patented refresh feature that ensures dc correctness in the absence of input logic transitions and during power-up/power-down conditions.This family of isolators, like many Analog Devices isolators, offers very low power consumption, consuming one-tenth to one-sixth the power of comparable isolators at comparable data rates up to 10 Mbps. All models of the ADuM440x provide low pulse width distortion (

The ADuM440x are 4-channel digital isolators based on the Analog Devices, Inc., iCoupler® technology. Combining high speed CMOS and monolithic air core transformer technology, these isolation components provide outstanding performance characteristics that are superior to the alternatives, such as optocoupler devices and other integrated couplers.The ADuM440x isolators provide four independent isolation channels in a variety of channel configurations and data rates (see the Ordering Guide). All models operate with the supply voltage on either side ranging from 3.0 V to 5.5 V, providing compatibility with lower voltage systems as well as enabling a voltage translation functionality across the isolation barrier. The ADuM440x isolators have a patented refresh feature that ensures dc correctness in the absence of input logic transitions and during power-up/power-down conditions.This family of isolators, like many Analog Devices isolators, offers very low power consumption, consuming one-tenth to one-sixth the power of comparable isolators at comparable data rates up to 10 Mbps. All models of the ADuM440x provide low pulse width distortion (