MIC39100/39101/39102 Micrel MIC39100/39101/39102 Evaluation Board 1A Low-Voltage Low-Dropout Regulator that indicates when the output falls out of regulation for any reason. The error flag output is an open-collector output, which is active-low, and requires a pull-up resistor for proper operation. Boards assembled with the MIC39101 have a 47kΩ pull-up resistor from FLG to the input voltage. The MIC39102 is an adjustable regulator that implements an enable pin that allows the user to disable the device. The enable pin is also active-high and requires that pin to be pulled high to turn-on the output and pulled low to disable the output. A jumper (JP1)is available to tie that pin to either the input or to ground. The output voltage of the MIC39102 is adjustable down to the band gap voltage of 1.24V. The board is set up with four set voltage options, A through D. A fifth option is available that can be custom set. The equation to set the output voltage is as follows: General Description This evaluation board can be used to evaluate several of Micrel’s new, low voltage, high current, low-dropout linear voltage regulators. The MIC39100 is a three-terminal LDO offered in the SOT-223 surface mount, power package. The MIC39101 is a 1A LDO in a power SO-8 package that offers the added functionality of an enable pin and an error flag output. The MIC39102 is an adjustable version of the MIC39100 in a power SO-8 package and it also has the added functionality of an enable pin, allowing the user to disable the device and put it into a zero-current off mode state. The board has two layouts, one on the topside to accommodate the MIC39100 and one on the backside to accommodate the MIC39101/2. This one board can easily be used to evaluate any one of these parts. R1 VOUT = VREF 1 + R2 Requirements The evaluation board requires a power supply capable of supplying a minimum of 1A of output current. The maximum voltage of that power supply should be at least 5V. These parts are intended for 3.3V to 2.5V and 3.3V or 2.5V to 1.8V conversion. A high voltage power supply should not be needed. The MIC39100/1/2 has an input voltage range of 2.25V to 16V, therefore it is not limited to just 5V systems. VREF = 1.24V On the board as it stands, R1 is set to 10kΩ. Using the equation and knowing that R1 = 10kΩ, a custom voltage can be determined by solving for R2 and placing an 0805 or 1206 resistor in the slot prepared and labeled E. Circuit Description VREF R2 = × R1 − V V OUT REF The MIC39100/1/2 regulators are simple to implement, requiring only an output capacitor for proper operation. An input cap is required when the power supply is greater than 4” away from the device. All evaluation boards include an input capacitor within 1” of the device. This is the recommended maximum distance away from the device that a capacitor should be placed. A minimum of 10µF of output capacitance is required for the MIC39100/1/2. Using large values of capacitance at the input and output will help to improve transient response. Table 1 shows the bill of materials for the different devices. 1.24V R2 = × 10kΩ VOUT − 1.24V Leaving all jumpers open sets the output voltage to the band gap voltage, 1.24V. Minimum Load All of the devices require a minimum load of 10mA. A resistor is included on the board to provide a minimum load of 10mA. The resistor value is different depending on the voltage option that the board has. The MIC39102 has a 140Ω resistor to maintain approximately 10mA at 1.4V output voltage. The 140Ω resistor can be changed to set a 10mA load depending upon the desired output voltage. MIC39101/MIC39102 The MIC39101 circuit implements an error flag and an enable function. The enable function allows the user to put the device into a zero-current off state when the regulator is not required. The enable pin is an active-high pin and needs to be pulled high (>2V) to enable the device and pulled low (< 0.8V) to disable the device. The error flag function is a voltage monitor Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com August 2000 1 MIC39100/39101/39102 MIC39100/39101/39102 Micrel MIC39100-x.xBM VIN IN VOUT OUT C2B C1B R1B GND GND Figure 1. MIC39100, SOT-223 Regulator Schematic MIC39101-X.XBM IN OUT VIN J2 C1 VOUT J5 R8 C2 R7 1 JP1 1–2 = on 2–3 = off Floating = off EN 2 3 GND FLG J3 FLAG J4 GND J6 Figure 2. MIC39101, Power SOP-8 Regulator Schematic MIC39102BM IN OUT VIN J2 VOUT J5 C1 C2 R6 10kΩ R8 R5 R4 R3 R2 R1 76.8kΩ 47.5kΩ 30.1kΩ 22.1kΩ open/custom 1 1–2 = on 2–3 = off Floating = off JP1 EN 2 3 GND ADJ J3 J4 GND J6 GND Figure 3. MIC39102, Adjustable Regulator Schematic MIC39100/39101/39102 2 August 2000 MIC39100/39101/39102 Micrel Bill of Materials Item Part Number C1B TPSC106M025R0500 AVX 10µF, 25V, Tantalum C2B TPSC106M025R10500 AVX 10µF, 25V, Tantalum 1 AVX 240Ω (2.5V) or 180Ω (1.8V) 5% 1/8W 1 LDO Regulator 1 R1B Manufacturer Description Micrel Qty. 1 U1B MIC39100-x.xBS C1 TPSC106M025R0500 AVX 10µF, 25V, Tantalum 1 C2 TPSC106M025R10500 AVX 10µF, 25V, Tantalum 1 470Ω 5% 1/8W, size 0805 1 R7 R8 AVX 240Ω (2.5V) or 180Ω (1.8V) 5% 1/8W 1 LDO Regulator 1 AVX 10µF, 25V, Tantalum 1 AVX 10µF, 25V, Tantalum 1 R2 22.1k 1% 1/8W, size 0805 1 R3 30.1k 1% 1/8W, size 0805 1 R4 47.5k 1% 1/8W, size 0805 1 R5 76.8k 1% 1/8W, size 0805 1 R6 10k 1% 1/8W, size 0805 1 140Ω 1% 1/8W, size 0805 1 LDO Regulator 1 U1 MIC39101-x.xBM C1 TPSC106M025R0500 C2 TPSC106M025R0500 R1 Open R7 Micrel Open R8 U1 August 2000 MIC39102BM Micrel 3 MIC39100/39101/39102 MIC39100/39101/39102 Micrel MICREL INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 TEL + 1 (408) 944-0800 FAX + 1 (408) 944-0970 WEB USA http://www.micrel.com This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc. © 2000 Micrel Incorporated MIC39100/39101/39102 4 August 2000