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ISL21007DFB812Z 数据表(PDF) 10 Page - Intersil Corporation |
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ISL21007DFB812Z 数据表(HTML) 10 Page - Intersil Corporation |
10 / 14 page 10 FN6326.1 April 12, 2007 Applications Information FGA Technology The ISL21007 voltage reference uses floating gate technology to create references with very low drift and supply current. Essentially the charge stored on a floating gate cell is set precisely in manufacturing. The reference voltage output itself is a buffered version of the floating gate voltage. The resulting reference device has excellent characteristics which are unique in the industry: very low temperature drift, high initial accuracy, and almost zero supply current. Also, the reference voltage itself is not limited by voltage bandgaps or zener settings, so a wide range of reference voltages can be programmed (standard voltage settings are provided, but customer-specific voltages are available). The process used for these reference devices is a floating gate CMOS process, and the amplifier circuitry uses CMOS transistors for amplifier and output transistor circuitry. While providing excellent accuracy, there are limitations in output noise level and load regulation due to the MOS device characteristics. These limitations are addressed with circuit techniques discussed in other sections. Micropower Operation The ISL21007 consumes extremely low supply current due to the proprietary FGA technology. Low noise performance is achieved using optimized biasing techniques. Supply current is typically 75µA and noise is 4µVP-P benefitting precision, low noise portable applications such as handheld meters and instruments. Data Converters in particular can utilized the ISL21007 as an external voltage reference. Low power DAC and ADC circuits will realize maximum resolution with lowest noise. Board Mounting Considerations For applications requiring the highest accuracy, board mounting location should be reviewed. The device uses a plastic SOIC package which will subject the die to mild stresses when the PC board is heated and cooled and slightly changes shape. Placing the device in areas subject to slight twisting can cause degradation of the accuracy of the reference voltage due to these die stresses. It is normally best to place the device near the edge of a board, or the shortest side, as the axis of bending is most limited at that location. Mounting the device in a cutout also minimizes flex. Obviously mounting the device on flexprint or extremely thin PC material will likewise cause loss of reference accuracy. Noise Performance and Reduction The output noise voltage in a 0.1Hz to 10Hz bandwidth is typically 4µVP-P. The noise measurement is made with a bandpass filter made of a 1 pole high-pass filter with a corner frequency at 0.1Hz and a 2-pole low-pass filter with a corner frequency at 12.6Hz to create a filter with a 9.9Hz bandwidth. Noise in the 10kHz to 1MHz bandwidth is approximately 40µVP-P with no capacitance on the output. This noise measurement is made with a 2 decade bandpass filter made of a 1 pole high-pass filter with a corner frequency at 1/10 of the center frequency and 1-pole low-pass filter with a corner frequency at 10 times the center frequency. Load capacitance up to 1000pF can be added but will result in only marginal improvements in output noise and transient response. The output stage of the ISL21007 is not designed to drive heavily capactive loads, so for load capacitances above 0.001µF the noise reduction network shown in Figure 28 is recommended. This network reduces noise significantly over the full bandwidth. Noise is reduced to less than 20µVP-P from 1Hz to 1MHz using this network with a 0.01µF capacitor and a 2k Ω resistor in series with a 10µF capacitor. Also, transient response is improved with higher value output capacitor. The FIGURE 27. PSRR vs CAPACITIVE LOADS Typical Performance Curves (ISL21007-25) (R EXT = 100kΩ) (Continued) -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 1 10 100 1k 10k 100k 1M FREQUENCY (Hz) VIN (DC) = 3V VIN (AC) = 50mVP-P 1nF LOAD NO LOAD 10nF LOAD ISL21007 |
类似零件编号 - ISL21007DFB812Z |
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类似说明 - ISL21007DFB812Z |
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