mic3838 Micrel Semiconductor, mic3838 Datasheet
mic3838
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mic3838 Summary of contents
Page 1
... The MIC3838 has a turn-on threshold of 12.5V whereas the MIC3839 has a lower turn-on threshold of 4.3V. Both devices are available in a small size MSOP-10 package with an operating range of –40°C to +85°C. ...
Page 2
... However, the error amplifier is internally current limited, so that zero duty cycle can be externally forced by pulling COMP to GND. The MIC3838 family features built-in full cycle soft start. Soft start is imple- mented as a clamp on the maximum COMP voltage. The inverting input to the error amplifier. ...
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... MOSFETs (OUTA and OUTB) and F is oscillator switching frequency. To prevent noise problems, bypass VDD to GND with a ceramic capacitor as close to the chip as possible. A 1µF decoupling capacitor is recommended. Internal 3V supply. Will source 1mA maximum. 3 Micrel current is the sum of DD MIC3838/3839 ...
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... V =10V, Note 10,1µF capacitor from Parameter Condition Internal Reference Section Output voltage I OUT Line Regulation MIC3838 9V ≤ V MIC3839 5V ≤ V Load Regulation I OUT Oscillator Section Oscillator Frequency Oscillator Amplitude/V Note 6 DD Error Amp Section Input Voltage ...
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... Parameter measured at trip point of latch with Note 10. The internal current sink on the Ramp and I path. Internal discharge FET should be able to discharge the Volt-Sec clamp and feed-forward circuits in the figure below within 50ns. Note 11. For MIC3838, set V above the start threshold before setting at 10V. DD Note 12 ...
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... V (V) DD Oscillator Frequency vs. RC Values C = 100pF V = 10V 220pF C = 270pF C = 330pF C = 470pF C = 680pF 100k C = 1000pF 10k 0 50k 100k 150k 200k RESISTANCE (kΩ) MIC3838 Oscillator Variation vs. Temperature 1. 10V 0.50 0.00 -0.50 -1.00 TEMPERATURE (°C) MIC3839 Error Amplifier Reference vs 2.04 2.02 2.00 1.98 1.96 1.94 1. ...
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... MIC3838/3839 MIC3839 Error Amplifier Reference vs. Temperature 2.040 2.030 10V 2.020 2.010 2.000 TEMPERATURE (°C) MIC3838 Peak Current Limit vs. Temperature 0.545 0.540 0.535 0.530 V = 10V IN 0.525 0.520 0.515 -40 - 100120140 TEMPERATURE (°C) MIC3838 3V Reference vs. Temperature 3.020 3.010 3.000 ...
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... Figure 2. Volt Second Clamp and Voltage Feed Forward Circuit Functional Description The MIC3838 high-speed power supply controller with push-pull output drive capability. MIC3838 has a higher V turn-on threshold and more hysteresis between V and turn-off than the MIC3839. The outputs of the controller operate in a push-pull fashion with a guaranteed dead time between them ...
Page 9
... Front edge blanking In current mode control, a PWM comparator uses the inductor current signal and the error amplifier signal to determine the operating duty cycle. In the MIC3838/9 the signal at the CS pin is level shifted up before it reaches the PWM comparator as shown in Figure 1. This allows operation of the error amplifier and PWM comparator in a linear region. There are two current limit thresholds in the MIC3838/9 ...
Page 10
... FETs and transformer. • current sense resistor is used, it’s ground end must be located very close to the ground pin of the MIC3838/9 controller. Careful PCB layout is necessary to keep the high current levels in the current sense resistor from running over the low level signals in the controller. • ...
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... BSC (0.193) 3.10 (0.122) 2.90 (0.114) 1.10 (0.043) 0.94 (0.037) 0.15 (0.006) 6° MAX 0.05 (0.002) 0° MIN 10-Pin MSOP (MM (408) 474-1000 FAX WEB Micrel for any damages resulting from such use or sale. © 2005 Micrel, Incorporated. 11 DIMENSIONS: MM (INCH) 0.26 (0.010) 0.10 (0.004) 0.70 (0.028) 0.40 (0.016) http://www.micrel.com MIC3838/3839 Micrel ...