D2985-3.3

D2985 150mA Low-Noise Ultra Low-Dropout Regulator General Description The D2985 is a 150 mA, fixed-output voltage regulator designed to provide ultra low-dropout and low noise in battery powered applications. The D2985 delivers unequalled performance in all specifications critical to battery-powered designs: SOT23-5 Dropout Voltage: Typically 300mV @ 150mA load, and 7mV @ 1mA load. Ground Pin Current: Typically 850µA @ 150mA load, and 75µA @ 1mA load. Enhanced Stability: The D2985 is stable with output capacitor ESR as low as 5mΩ, which allows the use of ceramic capacitors on the output. Sleep Mode: Less than 1 µA quiescent current when ON/OFF pin is pulled low. Smallest Possible Size: SOT-23-5L packages use absolute minimum board space. Precision Output: 1% tolerance output voltages available(A grade). Low Noise: By adding a 10nF bypass capacitor, output noise can be reduced to 30µV (typical). Multiple voltage options, from 2.5V to 5.0V, are available as standard products. Consult factory for custom voltages. Features  Ultra low dropout voltage  Guaranteed 150mA output current  Smallest possible size (SOT-23-5L package)  Requires minimum external components  Stable with low-ESR output capacitor  0.5V, and then reduces the maximum output current as VOUT is forced to ground (see Typical Performance Characteristics curves). * 10: Exposing the micro SMD device to direct sunlight will cause misoperation. See Application Hints for additional information. Shaoxing Silicore Technology Co.,Ltd. www. silicore. com. cn CHMC Oct. 2023 Rev. 1.2 Page 6 of 19 D2985 Application Summary External Capacitors Like any low-dropout regulator, the D2985 requires external capacitors for regulator stability. These capacitors must be correctly selected for good performance. Input Capacitor An input capacitor whose capacitance is ≥ 1 µF is required between the D2985 input and ground (the amount of capacitance may be increased without limit). This capacitor must be located a distance of not more than 1 cm from the input pin and returned to a clean analog ground. Any good quality ceramic, tantalum, or film capacitor may be used at the input. Important: Tantalum capacitors can suffer catastrophic failure due to surge current when connected to a low impedance source of power (like a battery or very large capacitor). If a Tantalum capacitor is used at the input, it must be guaranteed by the manufacturer to have a surge current rating sufficient for the application. There are no requirements for ESR on the input capacitor, but tolerance and temperature coefficient must be considered when selecting the capacitor to ensure the capacitance will be ≥ 1 µF over the entire operating temperature range. Output Capacitor The D2985 is designed specifically to work with ceramic output capacitors, utilizing circuitry which allows the regulator to be stable across the entire range of output current with an output capacitor whose ESR is as low as 5 mΩ. It may also be possible to use Tantalum or film capacitors at the output, but these are not as attractive for reasons of size and cost (see next section Capacitor Characteristics). The output capacitor must meet the requirement for minimum amount of capacitance and also have an ESR (equivalent series resistance) value which is within the stable range. Curves are provided which show the stable ESR range as a function of load current (see ESR graph below). Shaoxing Silicore Technology Co.,Ltd. www. silicore. com. cn CHMC Oct. 2023 Rev. 1.2 Page 7 of 19 D2985 Important: The output capacitor must maintain its ESR within the stable region over the full operating temperature range of the application to assure stability. The D2985 requires a minimum of 2.2 µF on the output(output capacitor size can be increased without limit). It is important to remember that capacitor tolerance and variation with temperature must be taken into consideration when selecting an output capacitor so that the minimum required amount of output capacitance is provided over the full operating temperature range. It should be noted that ceramic capacitors can exhibit large changes in capacitance with temperature (see next section, Capacitor Characteristics). The output capacitor must be located not more than 1 cm from the output pin and returned to a clean analog ground. Noise Bypass Capacitor Connecting a 10nF capacitor to the Bypass pin significantly reduces noise on the regulator output. It should be noted that the capacitor is connected directly to a high-impedance circuit in the bandgap reference. Because this circuit has only a few microamperes flowing in it, any significant loading on this node will cause a change in the regulated output voltage. For this reason, DC leakage current through the noise bypass capacitor must never exceed 100nA, and should be kept as low as possible for best output voltage accuracy. The types of capacitors best suited for the noise bypass capacitor are ceramic and film. High-quality ceramic capacitors with either NPO or COG dielectric typically have very low leakage. 10nF polypropolene and polycarbonate film capacitors are available in small surface-mount packages and typically have extremely low leakage current. Capacitor Characteristics Shaoxing Silicore Technology Co.,Ltd. www. silicore. com. cn CHMC Oct. 2023 Rev. 1.2 Page 8 of 19 D2985 The D2985 was designed to work with ceramic capacitors on the output to take advantage of the benefits they offer: for capacitance values in the 2.2µF to 4.7µF range, ceramics are the least expensive and also have the lowest ESR values (which makes them best for eliminating high frequency noise). The ESR of a typical 2.2µF ceramic capacitor is in the range of 10mΩ to 20mΩ, which easily meets the ESR limits required for stability by the D2985. One disadvantage of ceramic capacitors is that their capacitance can vary with temperature. Most large value ceramic capacitors (≥ 2.2µF) are manufactured with the Z5U or Y5V temperature characteristic, which results in the capacitance dropping by more than 50% as the temperature goes from 25°C to 85°C. This could cause problems if a 2.2µF capacitor were used on the output since it will drop down to approximately 1µF at high ambient temperatures (which could cause the D2985 to oscillate). If Z5U or Y5V capacitors are used on the output, a minimum capacitance value of 4.7µF must be observed. A better choice for temperature coefficient in ceramic capacitors is X7R, which holds the capacitance within ±15%. Unfortunately, the larger values of capacitance are not offered by all manufacturers in the X7R dielectric. Tantalum Tantalum capacitors are less desirable than ceramics for use as output capacitors because they are more expensive when comparing equivalent capacitance and voltage ratings in the1 µF to 4.7µF range. Another important consideration is that Tantalum capacitors have higher ESR values than equivalent size ceramics. This means that while it may be possible to find a Tantalum capacitor with an ESR value within the stable range, it would have to be larger in capacitance (which means bigger and more costly) than a ceramic capacitor with the same ESR value. It should also be noted that the ESR of a typical Tantalum will increase about 2:1 as the temperature goes from 25°C down to −40°C, so some guard band must be allowed. On/off Input Operation The D2985 is shut off by driving the ON/OFF input low, and turned on by pulling it high. If this feature is not to be used, the ON/OFF input should be tied to VIN to keep the regulator output on at all times. To assure proper operation, the signal source used to drive the ON/OFF input must be able to swing above and below the specified turn-on/turn-off voltage thresholds listed in the Electrical Characteristics section under VON/OFF. To prevent mis-operation, the turn-on (and turn-off) voltage signals applied to the ON/OFF input must have a slew rate which is≥ 40 mV/µs. Caution: the regulator output voltage can not be guaranteed if a slow-moving AC (or DC) signal is applied that is in the range between the specified turn-on and turn-off voltages listed under the electrical specification VON/OFF (see Electrical Characteristics). Shaoxing Silicore Technology Co.,Ltd. www. silicore. com. cn CHMC Oct. 2023 Rev. 1.2 Page 9 of 19 D2985 Reverse Input-output Voltage The PNP power transistor used as the pass element in the D2985 has an inherent diode connected between the regulator output and input. During normal operation (where the input voltage is higher than the output) this diode is reverse biased. However, if the output is pulled above the input, this diode will turn ON and current will flow into the regulator output. In such cases, a parasitic SCR can latch which will allow a high current to flow into VIN (and out the ground pin), which can damage the part. In any application where the output may be pulled above the input, an external Schottky diode must be connected from VIN to VOUT (cathode on VIN, anode on VOUT), to limit the reverse voltage across the D2985 to 0.3V (see Absolute Maximum Ratings). Micro Smd Mounting The micro SMD package requires specific mounting techniques which are detailed in National Semiconductor Application Note # 1112. Referring to the section Surface Mount Technology (SMT) Assembly Considerations, it should be noted that the pad style which must be used with the 5-pin package is the NSMD (non-solder mask defined) type. For best results during assembly, alignment ordinals on the PC board may be used to facilitate placement of the micro SMD device. Micro Smd Light Sensitivity Exposing the micro SMD device to direct sunlight will cause misoperation of the device. Light sources such as Halogen lamps can also affect electrical performance if brought near to the device. The wavelenghts which have the most detrimental effect are reds and infra-reds, which means that the fluorescent lighting used inside most buildings has very little effect on performance. A micro SMD test board was brought to within 1 cm of a fluorescent desk lamp and the effect on the regulated output voltage was negligible, showing a deviation of less than 0.1% from nominal. Shaoxing Silicore Technology Co.,Ltd. www. silicore. com. cn CHMC Oct. 2023 Rev. 1.2 Page 10 of 19 D2985 Application Current Shaoxing Silicore Technology Co.,Ltd. www. silicore. com. cn CHMC Oct. 2023 Rev. 1.2 Page 11 of 19 D2985 Typical Characteristics Unless otherwise specified: CIN = 1µF, COUT = 4.7µF, VIN = VOUT(NOM) +1, TA = 25°C, ON/OFF pin is tied to VIN. Shaoxing Silicore Technology Co.,Ltd. www. silicore. com. cn CHMC Oct. 2023 Rev. 1.2 Page 12 of 19 D2985 Shaoxing Silicore Technology Co.,Ltd. www. silicore. com. cn CHMC Oct. 2023 Rev. 1.2 Page 13 of 19 D2985 Shaoxing Silicore Technology Co.,Ltd. www. silicore. com. cn CHMC Oct. 2023 Rev. 1.2 Page 14 of 19 D2985 Shaoxing Silicore Technology Co.,Ltd. www. silicore. com. cn CHMC Oct. 2023 Rev. 1.2 Page 15 of 19 D2985 Shaoxing Silicore Technology Co.,Ltd. www. silicore. com. cn CHMC Oct. 2023 Rev. 1.2 Page 16 of 19 D2985 Shaoxing Silicore Technology Co.,Ltd. www. silicore. com. cn CHMC Oct. 2023 Rev. 1.2 Page 17 of 19 D2985 Outline Dimensions SOT23-5： H A1 θ L C A2 A Unit:mm D E E1 b e e1 Symbol A A1 A2 b c D E E1 e e1 L θ Dimensions In Millimeters Min Max 0.700 0.900 0.000 0.100 0.700 0.800 0.350 0.500 0.080 0.200 2.820 3.020 1.600 1.700 2.650 2.950 0.95（BSC） 1.90（BSC） 0.300 0.600 0° 8° Shaoxing Silicore Technology Co.,Ltd. www. silicore. com. cn CHMC Dimensions In Inches Min Max 0.028 0.035 0.000 0.004 0.028 0.031 0.014 0.020 0.003 0.008 0.111 0.119 0.063 0.067 0.104 0.116 0.037(BSC) 0.075(BSC) 0.012 0.024 0° 8° Oct. 2023 Rev. 1.2 Page 18 of 19 D2985 Statements  Silicore Technology reserves the right to make changes without further notice to any products or specifications herein. Before customers place an order, customers need to confirm whether datasheet obtained is the latest version, and to verify the integrity of the relevant information.  Failure or malfunction of any semiconductor products may occur under particular conditions, customers shall have obligation to comply with safety standards when customers use Silicore Technology products to do their system design and machine manufacturing, and take corresponding safety measures in order to avoid potential risk of failure that may cause personal injury or property damage.  The product upgrades without end, Silicore Technology will wholeheartedly provide customers integrated circuits that have better performance and better quality. Shaoxing Silicore Technology Co.,Ltd. www. silicore. com. cn CHMC Oct. 2023 Rev. 1.2 Page 19 of 19