3BHB系列電壓
3BHB系列電壓基準具有集成的低輸出阻抗緩沖器（ADC驅(qū)動緩沖器）；因此，驅(qū)動高精度、高通量SAR ADC的REF引腳時不需要外部緩沖器，如圖49所示。3BHB004692R0002的ADC驅(qū)動緩沖器能夠在1μs內(nèi)補充47μF電容器上70 pC的電荷，而不允許電容器上的電壓在18位精度下下降超過1 LSB。 x在生產(chǎn)過程中在多個溫度下進行微調(diào)，最大漂移僅為3±4±3±2±1 1輸出阻抗（ü）頻率（Hz） 帶隙電壓參考30版權所有 續(xù)）0°C至70°C之間的參考電壓和緩沖電壓，同時在820μa的典型靜態(tài)電流下運行?；鶞势票ＷC在0°C和70°C之間。REF62xx可在-55°C至125°C的溫度下運行，而不會損壞。圖50比較了常規(guī)電壓基準（REF20xx）和帶集成ADC驅(qū)動緩沖器（ 的電壓基準的輸出阻抗。圖51比較了常規(guī)電壓基準和REF62xx的突發(fā)模式、基準穩(wěn)定性能。圖 3BHB004692R0002驅(qū)動REF引腳 輸出阻抗比較1 LSB=19.07μV，與ADS8851在1 MSPS圖51。參考壓降k版權所有 9.3.2溫度漂移REF62xx系列設計用于最小漂移誤差，定義為輸出電壓隨溫度的變化。
輸出電容值范圍
穩(wěn)定性3BHB系列電壓基準電壓穩(wěn)定，輸出電容值范圍為10μF至47μF。在10μF的低輸出電容值下，需要20 mΩ至100 mΩ的有效串聯(lián)電阻（ESR）才能穩(wěn)定；而在47μF的較高值下，需要5 mΩ至100 mΩ的ESR。圖52中的陰影區(qū)域顯示了REF62xx設備的穩(wěn)定運行區(qū)域。圖52.穩(wěn)定輸出電容器范圍FILT引腳需要1μF值的電容器，以確保穩(wěn)定性和噪聲性能。通過增加PCB跡線長度，可以輕松實現(xiàn)低ESR（5 mΩ至20 mΩ），從而無需使用分立電阻器?？梢杂幸馓砑痈叩腅SR值（大于20 mΩ，但小于100 mΩ），以增加REF62xx的輸出帶寬。較高的ESR提高了REF62xx的瞬態(tài)性能，但由于帶寬增加，噪聲性能惡化。9.4設備功能模式當REF62xx的EN引腳被拉高時，設備處于激活模式。設備必須處于活動模式才能正常運行。要將REF62xx置于關閉模式，將ENABLE引腳拉低。在關機模式下，設備的輸出變?yōu)楦咦杩?，設備的靜態(tài)電流降至1μA（典型值）。有關邏輯高電壓電平和邏輯低電壓電平，請參閱電氣特性表中的啟用引腳電壓參數(shù)。
3BHB series voltage
3BHB series voltage reference has integrated low output impedance buffer (ADC drive buffer); Therefore, when driving the REF pin of high-precision and high-throughput SAR ADC, no external buffer is required, as shown in Figure 49. The ADC drive buffer of 3BHB004692R0002 can supplement the charge of 70 pC on the 47 μ F capacitor within 1 μ s, without allowing the voltage on the capacitor to drop more than 1 LSB with 18 bit accuracy. X Fine adjustment is carried out at multiple temperatures during production, and the maximum drift is only 3 ± 4 ± 3 ± 2 ± 1 1 Output impedance (U) Frequency (Hz) Band gap voltage reference 30 Copyright continued) Reference voltage and buffer voltage between 0 ° C and 70 ° C, while operating at 820 μ a typical static current. The reference drift is guaranteed to be between 0 ° C and 70 ° C. The REF62xx can operate at temperatures from - 55 ° C to 125 ° C without damage. Figure 50 compares the conventional voltage reference (REF20xx) with the drive buffer with integrated ADC (output impedance of voltage reference. Figure 51 compares the burst mode and reference stability performance of conventional voltage reference and REF62xx. Figure 3BHB004692R0002 compares the output impedance of drive REF pin 1 LSB=19.07 μ V with ADS8851 in 1 MSPS Figure 51. Refer to Voltage Drop k Copyright 9.3.2 Temperature Drift REF62xx series is designed for minimum drift error, which is defined as the change of output voltage with temperature.
Output capacitance value range
Stability The voltage reference voltage of 3BHB series is stable, and the output capacitance value range is 10 μ F to 47 μ F. Under the low output capacitance value of 10 μ F, an effective series resistance (ESR) of 20 m Ω to 100 m Ω is required to be stable; At a higher value of 47 μ F, an ESR of 5 m Ω to 100 m Ω is required. The shaded area in Figure 52 shows the stable operation area of the REF62xx device. Figure 52. Stable output capacitor range The FILT pin requires a capacitor with a value of 1 μ F to ensure stability and noise performance. By increasing the PCB trace length, it is easy to achieve low ESR (5 m Ω to 20 m Ω) without using discrete resistors. A higher ESR value (greater than 20 m Ω, but less than 100 m Ω) can be intentionally added to increase the output bandwidth of REF62xx. The higher ESR improves the transient performance of REF62xx, but the noise performance deteriorates due to the increase of bandwidth. 9.4 Device function mode When the EN pin of REF62xx is pulled up, the device is in the active mode. The device must be in active mode to function properly. To place REF62xx in OFF mode, pull down the ENABLE pin. In the shutdown mode, the output of the device becomes high impedance, and the static current of the device drops to 1 μ A (typical value). For the logic high voltage level and logic low voltage level, refer to the Enable Pin Voltage parameter in the Electrical Characteristics table.
