Analog Devices Inc./Maxim Integrated

The LTC1550L/LTC1551L are switched capacitor charge pump voltage inverters which include internal linear post-regulators to minimize output ripple. The LTC1550L fixed output voltage versions include ±4.1V, ±2.5V and ±2V with ripple voltages typically below 1mVP-P. The LTC1550L is also available in an adjustable output voltage version. The LTC1550L/LTC1551L are ideal for use as bias voltage generators for GaAs transmitter FETs in portable RF and cellular telephone applications.The LTC1550L/LTC1551L operate from single 2.7V to 5.5V supplies and draw typical quiescent currents of 3.5mA with a 5V supply. Each device includes a TTL compatible Shutdown pin which drops supply current to 0.2µA typically. The LTC1550L Shutdown pin is active low (SHDN), while the LTC1551L Shutdown pin is active high (SHDN). Only four external components are required: an input bypass capacitor, two 0.1µF charge pump capacitors and a filter capacitor at the linear regulator output. The adjustable LTC1550L/LTC1551L require two additional resistors to set the output voltage. The LTC1550L/LTC1551L will supply up to 20mA (depending on VCCto VOUTrange), while maintaining guaranteed output regulation of ±2.5%.Both fixed voltage and adjustable LTC1550L/LTC1551L are available in 8-lead MSOP and SO plastic packages: the adjustable LTC1550L is also available in a 16-pin SSOP with the REG pin.ApplicationsGaAs FET Bias GeneratorsNegative Supply GeneratorsBattery-Powered SystemsSingle Supply Applications

The LTC1553 is a high power, high efficiency switching regulator controller optimized for 5V or 12V input to 1.8V-3.5V output applications. It features a digitally programmable output voltage, a precision internal reference and an internal feedback system that provides output accuracy of ±1.5% at room temperature and typically ±2% over-temperature, load current and line voltage shifts. The LTC1553 uses a synchronous switching architecture with two external N-channel output devices, providing high efficiency and eliminating the need for a high power, high cost P-channel device. Additionally, it senses the output current across the on-resistance of the upper N-channel FET, providing an adjustable current limit without an external low value sense resistor.The LTC1553 free-runs at 300kHz and can be synchronized to a faster external clock if desired. It includes all the inputs and outputs required to implement a power supply conforming to the Intel Pentium®II Processor VRM 8.2 DC/DC Converter Specification.ApplicationsPower Supply for Pentium II, SPARC, ALPHA and PA-RISC MicroprocessorsHigh Power 5V or 12V to 1.8V-3.5V Regulators

The LTC1553L is a high power, high efficiency switching regulator controller optimized for a 5V input to 1.8V-3.5V output applications. It features a digitally programmable output voltage, a precision internal reference and an internal feedback system that provides output accuracy of ±1.5% at room temperature and typically ±2% over-temperature, load current and line voltage shifts. The LTC1553L uses a synchronous switching architecture with two external N-channel output devices, providing high efficiency and eliminating the need for a high power, high cost P-channel device. Additionally, it senses the output current across the on-resistance of the upper N-channel FET, providing an adjustable current limit without an external low value sense resistor.The LTC1553L free-runs at 300kHz and can be synchronized to a faster external clock if desired. It includes all the inputs and outputs required to implement a power supply conforming to the Intel Pentium®II Processor VRM 8.2 DC/DC Converter Specification.ApplicationsPower Supply for Pentium II, SPARC, ALPHA and PA-RISC MicroprocessorsHigh Power 5V to 1.8V-3.5V Regulators

The LTC1555L provides power conversion and level shifting needed for low voltage GSM cellular telephones to interface with either 3V or 5V Subscriber Identity Modules (SIMs). The part contains a patented buck/boost charge pump DC/DC converter* that delivers a regulated VCCsupply voltage to the SIM card. Input voltage may range from 2.6V to 6V allowing direct connection to the battery. The output voltage may be programmed to 3V, 5V or direct connection to the VINpin.Internal level translators allow controllers operating with supplies as low as 1.425V to interface with 3V and 5V SIMs. A soft-start feature limits inrush current at turn-on, mitigating start-up problems that may result when the input is supplied by another low-power DC/DC converter. Battery life is maximized by 40µA operating current, and 1µA shutdown current. Board area is minimized by the miniature 16-pin narrow SSOP packages and the need for only three small external capacitors.ApplicationsSIM Interface in GSM Cellular TelephonesSmart Card Readers

The LTC1555L-1.8 provides power conversion and level shifting needed for low voltage GSM and WCDMA cellular telephones to interface with either 1.8V, 3V or 5V subscriber identity modules (SIMs). The part contains a patented buck/boost charge pump DC/DC converter* that delivers a regulated VCCsupply voltage to the SIM card. Input voltage may range from 2.6V to 6V allowing direct connection to the battery. The output voltage may be programmed to 1.8V, 3V, 5V or direct connection to the VINpin.Internal level translators allow controllers operating with supplies as low as 1.425V to interface with 1.8V, 3V and 5V SIMs. A soft-start feature limits inrush current at turn-on, mitigating start-up problems that may result when the input is supplied by another low-power DC/DC converter. Battery life is maximized by 32µA operating current, and 1µA shutdown current. Board area is minimized by the miniature 16-pin narrow SSOP packages and the need for only three small external capacitors.ApplicationsSIM Interface in GSM Cellular TelephonesWCDMA SIM InterfaceSmart Card Readers

The LTC1555/LTC1556 provide power conversion and level shifting needed for 3V GSM cellular telephones to interface with either 3V or 5V Subscriber Identity Modules (SIMs). These parts contain a charge pump DC/DC converter that delivers a regulated 5V to the SIM card. Input voltage may range from 2.7V to 10V, allowing direct connection to the battery. Output voltage may be programmed to 3V, 5V or direct connection to the VINpin.A soft start feature limits inrush current at turn-on, mitigating start-up problems that may result when the input is supplied by another low power DC/DC converter. The LTC1556 also includes an auxiliary LDO regulator/power switch that may be used to power the frequency synthesizer or other low power circuitry.Battery life is maximized by 60µA operating current and 1µA shutdown current. Board area is minimized by miniature 16- and 20-pin narrow SSOP packages and the need for only three small external capacitors.ApplicationsSIM Interface in GSM Cellular TelephonesSmart Card Readers

The LTC1560-1 is a 5th order, continuous-time, lowpass filter. The elliptic transfer function of the LTC1560-1 was carefully chosen to reach a compromise between selectivity, for antialiasing applications, and transient response. The filter cutoff frequency, fCUTOFF, is pin selectable to either 500kHz (Pin 5 to V+) or 1MHz (Pin 5 to V–). When programmed for 1MHz, the passband ripple is typically ±0.2dB up to 0.55fCUTOFFand ±0.3dB to 0.9fCUTOFF. The transition band gain is –24dB at 1.4fCUTOFFand –51dB at 2fCUTOFF. Stopband attenuation is 63dB at 2.43fCUTOFFand above, remaining at least 60dB to 10MHz with proper board layout. When the LTC1560-1 is programmed for fCUTOFF= 500kHz, the filter response closely follows the 1MHz case with the exception of passband flatness near the cutoff frequency; the gain at fCUTOFFis –1.3dB.The LTC1560-1, unlike other high frequency filters, is designed for low noise and low distortion. With a 1VRMSinput signal, the signal-to-noise ratio is 69dB and the THD is –63dB. The maximum SNR of 75dB is obtained with a 2.1VRMSinput signal. This results in –46dB THD.The LTC1560-1 operates with ±5V supplies, has a power saving mode and is available in an SO-8 surface mount package.Other cutoff frequencies from 450kHz to 1.5MHz can be obtained. Demo board DC135A is available for the LTC1560-1. For more information please contact LTC Marketing.ApplicationsAntialiasing FiltersSmoothing or Reconstruction FiltersCommunication Filters

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. Unlike most monolithic filters, no clock is needed. Four independent 2nd order filter blocks can be cascaded in any combination, such as one 8th order or two 4th order filters. Each block’s response is programmed with three external resistors for 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. All pass, 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 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.ApplicationsHigh Resolution Systems (14 Bits to 18 Bits)Antialiasing/Reconstruction FiltersData Communications, EqualizersDual or I-and-Q Channels (Two Matched 4th Order Filters in One Package)Linear Phase FilteringReplacing LC Filter Modules