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1、1Linear Technology Chronicle December 1995Product of the MonthA Showcase of Linear Technologys Focus ProductsLinear Technology ChronicleDecember 1995Vol. 4 No. 12Micropower 12-Bit Serial A/D Converters with 4-Channel Multiplexer Consumes Only 160A, LTC and LT are registered trademarks of Linear Tech
2、nology Corporation.Figure 1. LTC1594L 4-Channel, 3V, 12-Bit ADC Samples at 200Hz1.5V, 3A Low Dropout Linear Regulator Has Fast Transient Response for Providing GTL+ Termination Voltage . 21MHz Step-Down Converter Ends 455kHz IF Woes . 3900kHz Low Noise Surface Mount Voltage Inverters Provide Regulat
3、ed 4.1V for GaAs FETs. 3New 800mA Low Dropout Sink/Source Regulators for Split Supplies in Single Supply Applications . 4Inside This Issue:The LTC1594L and LTC1594 are 3V and 5V 12-bit serial A/D converters with 4-channel multiplexers. These new A/D con- verters feature power dissipation as low as 0
4、.48mW on a single 3V supply while provid- ing a 60s conversion time. When not converting, the LTC1594L/LTC1594 auto- matically power down to a mere 1nA of supply current, making the LTC1594 ideal for battery-powered data acquisition systems and portable pen-based PC products. Figure 1 shows a diagra
5、m of the LTC1594L run- ning on a 3V battery.The LTC1594 serial ports allow effi- cient data transfer to a wide range ofmicroprocessors and microcontrollers over three wires. These A/D converters are I/O compatible with the SPI and MICROWIRETM interfaces. This, coupled with low power consumption, mak
6、es remote location possible and facilitates transmitting data through isolation barriers. High imped- ance analog inputs and the ability to operate with reduced spans (to 1.5V full-scale) allow direct connection to sensors and transducers in many applications, eliminating the need for gain stages.Th
7、e LTC1594 is ideal for pen-screen digitizing, remote data acquisition, isolated data acquisition, battery monitoring and tem-3V1FANALOG INPUTS? 0V TO 3V RANGEVCC?MUX OUT?DIN?CS?CLK?VCC?DOUT?CSCH0?CH1?CH2?CH3?SHA IN?VREF?COM?GNDLTC1594LMPU? SERIAL DATA LINK? (MICROWIRE AND ? SPI COMPATIBLE)LTC1522 TA
8、011?2?3?4?5?6?7?8?16?15?14?13?12?11?10?9SERIAL DATA LINKperature measurement. The LTC1594L and LTC1594 are available in a 16-lead narrow plastic surface mount package. Devices are specified over 0C to 70C. For a data sheet and free evaluation samples of the LTC1594L/LTC1594 contact your local Linear
9、 Technology sales office.MICROWIRE is a trademark of National Semiconductor Corporation.Continued on page 21?2?3?4?5?6?7?8TOP VIEW16?15?14?13?12?11?10?9OUTB?OUTA?V+?INA?INA+?INB?INB+?REFOUTC?OUTD?HYST?IND+?IND?INC+?INC?VS PACKAGE? 16-LEAD PLASTIC SO? ?N PACKAGE? 16-LEAD PDIPThe LTC1444/45 Provide a
10、Hysteresis Programming PinQuad Micropower Comparators with 1% Accurate Reference Have 8.5A Maximum Supply CurrentThe LTC1443, LTC1444, LTC1445 quad micropower comparators feature a built-in voltage reference and guaranteed maximum 8.5A supply current over their full operating temperature range. Typi
11、cally these devices require only 1.3A per com- parator. This low supply current combined with 2V supply voltage capability make these new comparators ideal for use in por- table battery-operated systems. All these new quad comparators have a propagation delay of 12s (10mV overdrive). The LTC1443 has
12、 a 1.182V 1% reference and is a drop-in upgrade to the older 924 device. The LTC1444 and LTC1445 have a 1.221V 1% reference and provide other features not available in other devices. Figure 1 shows the pinout of the proprietary LTC1444 and LTC1445 quad comparators.2Linear Technology Chronicle Decemb
13、er 1995Two new features have been introduced with these new micropower quad compara- tors. First, the HYST pin on the LTC1444 and LTC1445 allows programming of com- parator hysteresis with only two resistors, easing calculation of proper resistor values and eliminating the increase in supply cur- re
14、nt when compared to the 3-resistor approach of the other comparators. Sec- ondly, the guaranteed 1% accurate reference on board the LTC1443/44/45 can drive a ca- pacitive load of up to 0.01F. The capacitive load driving capability of the reference eliminates problems with input transients feeding th
15、rough the device and provides faster settling time. Input transients com-monly occur when switching from the main battery pack to a backup battery or wall socket voltage in portable computers. The reference output on the LTC1443/44/45 sources up to 100A, (25 times more current than the reference on the 924), making the LTC1443/44/45 reference available for use in other system area
