LINEAR Manuals

The LTC ®1603 is a 250ksps, 16-bit sampling A/D con- verter that draws only 220mW from ±5V supplies. This high performance device includes a high dynamic range sample-and-hold, a precision reference and a high speed parallel output. Two digitally selectable power shutdown modes provide power savings for low power systems.

LT1638/LT1639 are super micro power rail-to-rail input and output operational amplifiers with a frequency of 1.2MHz and a slew rate of 0.4V/µs. They operate with inputs above V+, have low power consumption, high output current, etc. They are suitable for portable instrumentation, sensor conditioning, battery monitoring, micro power active filters, 4mA to 20mA transmitters, etc.

The LT ®1949 is a fixed frequency step-up DC/DC converter with a 1A, 0.5Ω internal switch. Capable of generating 10V at 175mA from a 3.3V input, the LT1949 is ideal for generating bias voltages for large screen LCD panels.

The LT1785/LT1791 are half-duplex and full-duplex differential bus transceivers for RS485 and RS422 applications which feature on-chip protection from overvoltage faults on the data transmission lines. Receiver input and driver output pins can withstand voltage faults up to ±60V with respect to ground with no damage to the device. Faults may occur while the transceiver is active, shut down or powered off. Data rates to 250kbaud on networks of up to 128 nodes are supported. Controlled slew rates on the driver outputs control EMI emissions and improve data transmission integrity on improperly terminated lines. Drivers are specified to operate with inexpensive cables as low as 72Ω characteristic impedance. The LT1785A/LT1791A devices have “fail-safe” receiver inputs to guarantee a receiver output high for shorted, open or inactive data lines. On-chip ESD protection eliminates need for external protection devices. The LT1785/LT1785A are available in 8-lead DIP and SO packages and the LT1791/LT1791A in 14-lead DIP and SO packages.

The LTC1657/LTC1657L are complete single supply, rail-to-rail voltage output, 16-bit digital-to-analog converters (DAC) in a 28-pin SSOP or PDIP package. They include a rail-to-rail output buffer amplifier, an internal reference and a double buffered parallel digital interface. The LTC1657/LTC1657L have separate reference input pins that can be driven by an external reference. The full-scale output can be 1 or 2 times the reference voltage depending on how the X1/X2 pin is connected. The LTC1657 operates from a 4.5V to 5.5V supply and has an onboard 2.048V reference. The LTC1657L operates from a 2.7V to 5.5V supply and has an onboard 1.25V reference. The LTC1657/LTC1657L are similar to Linear Technology Corporation’s LTC1450/LTC1450L 12-bit VOUT DAC family, allowing an upgrade path. They are the only buffered 16-bit parallel DACs in a 28-lead SSOP package and include an onboard reference for stand alone performance.

The LT1027 is a precision reference voltage from Linear Technology Corporation that features ultra-low drift, superior accuracy, excellent line and load regulation, and low output impedance at high frequency. This device is intended for use in 12- to 16-bit A/D and D/A systems where demanding accuracy requirements must be met without the use of power hungry, heated substrate references. The fast settling output recovers quickly from load transients such as those presented by A/D converter reference inputs. The LT1027 brings together both outstanding accuracy and temperature coefficient specifications. The LT1027 reference is based on LTC's proprietary advanced subsurface Zener bipolar process which eliminates noise and stability problems associated with surface breakdown.

The LT1019 is a third generation bandgap voltage reference utilizing thin film technology and a greatly improved curvature correction technique.

The LTC3827-1 is a high-performance dual step-down switching regulator controller with features such as low operating IQ, wide input voltage range, and adjustable output voltage soft-start.

The LT1207 dual 250mA/60MHz current feedback amplifier features a 250mA minimum output drive current, 60MHz bandwidth, 900V/µs slew rate, 0.02% differential gain, and 0.17° differential phase.

LTC2404/LTC2408 4-/8-channel 24-bit µPower No Latency ∆ΣTM ADCs with integrated oscillator, 4ppm INL and 0.3ppm RMS noise. They use delta-sigma technology and provide single cycle digital filter settling time (no latency delay) for multiplexed applications. The first conversion after the channel is changed is always valid. Through a single pin the LTC2404/ LTC2408 can be configured for better than 110dB rejec- tion at 50Hz or 60Hz ±2%, or can be driven by an external oscillator for a user defined rejection frequency in the range 1Hz to 120Hz. The internal oscillator requires no external frequency setting components. The converters accept any external reference voltage from 0.1V to VCC. With their extended input conversion range of –12.5% VREF to 112.5% VREF the LTC2404/LTC2408 smoothly resolve the offset and overrange problems of preceding sensors or signal conditioning circuits. The LTC2404/LTC2408 communicate through a flexible 4-wire digital interface which is compatible with SPI and MICROWIRE TM protocols.

This datasheet provides detailed information about LTC2293/LTC2292/LTC2291, including features, applications, typical applications, specifications, and packages.

The LTC1562-2 is a low noise, low distortion continuous time filter with rail-to-rail inputs and outputs, optimized for a center frequency (fO) of 20kHz to 300kHz. It does not require a clock signal. The filter consists of four independent 2nd order filter blocks that can be cascaded in any combination, such as one 8th order or two 4th order filters. The response of each block can be programmed with three external resistors to set the center frequency, Q, and gain using simple design formulas. Each 2nd order block provides lowpass and bandpass outputs. Highpass response is available if an external capacitor replaces one of the resistors. Allpass, notch, and elliptic responses can also be realized. The LTC1562-2 is designed for applications where dynamic range is important. For example, by cascading 2nd order sections in pairs, the user can configure the IC as a dual 4th order Butterworth lowpass filter with a 90dB signal-to-noise ratio from a single 5V power supply. Low level signals can exploit the built-in gain capability of the LTC1562-2. Varying the gain of a section can achieve a dynamic range as high as 114dB with a ±5V supply. Other cutoff frequency ranges can be provided upon request. Please contact LTC Marketing. LTC, LT are registered trademarks of Linear Technology Corporation.

The LT1579 is a dual input, single output, low dropout regulator designed to provide an uninterruptible output voltage from two independent input voltage sources on a priority basis. All of the circuitry needed to switch smoothly and automatically between inputs is incorporated. The LT1579 can supply 300mA of output current from either input at a dropout voltage of 0.4V. Quiescent current is 50µA, dropping to 7µA in shutdown. Two comparators are included to monitor input voltage status. Two additional status flags indicate which input is supplying power and provide an early warning against loss of output regulation when both inputs are low. A secondary select pin is provided so that the user can force the device to switch from the primary input to the secondary input. Internal protection circuitry includes reverse-battery protection, current limiting, thermal limiting and reverse-current protection. The device is available in fixed output voltages of 3V, 3.3V and 5V, and as an adjustable device with a 1.5V reference voltage. The LT1579 regulators are available in narrow 16-lead SO and 16-lead SSOP packages with all features, and in SO-8 with limited features.

This document provides detailed information on the design decisions made for a converter and describes methods for modifying the design for various applications. The document describes the design of an isolated version of the converter and the VCC power start-up method. It also explains how to program the output voltage by adjusting resistor values and how to select the frequency.

The LTC3706/26 secondary-side synchronous controller and its companion smart gate driver, the LTC3705/25, make it possible to create an isolated forward converter with the simplicity and performance of the familiar buck converter