MAX5974A MAXIM [Maxim Integrated Products], MAX5974A Datasheet
MAX5974A
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MAX5974A Summary of contents
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... General Description The MAX5974_ provide control for wide-input-voltage, active-clamped, current-mode PWM, forward converters in Power-over-Ethernet (PoE) powered device (PD) appli- cations. The MAX5974A/MAX5974C are well-suited for universal or telecom input range, while the MAX5974B/ MAX5974D also accommodate low input voltage down to 10.5V. The devices include several features to enhance supply efficiency ...
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... Current-Mode PWM Controllers ABSOLUTE_MAXIMUM_RATINGS IN to GND ..............................................................-0.3V to +24V EN, NDRV, AUXDRV to GND .....................-0. RT, DT, FFB, COMP, SS, DCLMP, DITHER/SYNC to GND .................................................................-0. GND (MAX5974A/MAX5974B only) ..................- GND (MAX5974C/MAX5974D only) ..............-0.3V to +6V CS, CSSC to GND ...................................................-0.8V to +6V PGND to GND ......................................................-0.3V to +0.3V Maximum Input/Output Current (continuous) NDRV, AUXDRV ............................................................100mA NDRV, AUXDRV (pulsed for less than 100ns) .................. Q1A Note_1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four- layer board ...
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... Active-Clamped, Spread-Spectrum, ELECTRICAL_CHARACTERISTICS_(continued 12V (for MAX5974A/MAX5974C, bring +2V, NDRV = AUXDRV = SS = COMP = unconnected, R GND EN unless otherwise noted. Typical values are at T PARAMETER SYMBOL SYNCHRONIZATION_(SYNC) Synchronization Logic-High Input Synchronization Pulse Width Synchronization Frequency Range Maximum Duty Cycle During Synchronization DITHERING_RAMP_GENERATOR_(DITHER) Charging Current Discharging Current Ramp’ ...
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... Active-Clamped, Spread-Spectrum, Current-Mode PWM Controllers ELECTRICAL_CHARACTERISTICS_(continued 12V (for MAX5974A/MAX5974C, bring +2V, NDRV = AUXDRV = SS = COMP = unconnected, R GND EN unless otherwise noted. Typical values are at T PARAMETER SYMBOL AUXDRV_DRIVER Pulldown Impedance Pullup Impedance Peak Sink Current Peak Source Current Fall Time Rise Time ...
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... Active-Clamped, Spread-Spectrum, ELECTRICAL_CHARACTERISTICS_(continued 12V (for MAX5974A/MAX5974C, bring +2V, NDRV = AUXDRV = SS = COMP = unconnected, R GND EN unless otherwise noted. Typical values are at T PARAMETER SYMBOL ERROR_AMPLIFIER FB Reference Voltage FB Input Bias Current Voltage Gain Transconductance Transconductance Bandwidth Source Current Sink Current FREQUENCY_FOLDBACK_(FFB) V -to-FFB Comparator ...
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... Active-Clamped, Spread-Spectrum, Current-Mode PWM Controllers (V = 12V (for MAX5974A/MAX5974C, bring 2V, NDRV = AUXDRV = SS = COMP = unconnected, R GND EN IN UVLO WAKE-UP LEVEL vs. TEMPERATURE 20.1 MAX5974A/MAX5974C 20.0 19.9 19.8 19.7 19.6 19.5 -40 - TEMPERATURE (°C) EN RISING THRESHOLD vs. TEMPERATURE 1.220 1.218 1.216 1.214 1.212 1.210 -40 - TEMPERATURE (°C) SUPPLY CURRENT vs. SUPPLY VOLTAGE ...
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... Active-Clamped, Spread-Spectrum 12V (for MAX5974A/MAX5974C, bring 2V, NDRV = AUXDRV = SS = COMP = unconnected, R GND EN SOFT-START CHARGING CURRENT vs. TEMPERATURE 10.06 10.05 10.04 10.03 10.02 10.01 10.00 9.99 9.98 9.97 -40 - TEMPERATURE (°C) FREQUENCY DITHERING vs. R DITHER 300 400 500 600 700 800 900 R (kΩ) DITHER MAXIMUM DUTY CYCLE vs ...
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... Active-Clamped, Spread-Spectrum, Current-Mode PWM Controllers (V = 12V (for MAX5974A/MAX5974C, bring 2V, NDRV = AUXDRV = SS = COMP = unconnected, R GND EN DEAD TIME vs. R VALUE DT 400 350 300 250 200 150 100 VALUE (kΩ) DT REVERSE CURRENT-LIMIT THRESHOLD vs. TEMPERATURE -97 -98 -99 -100 ...
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... Active-Clamped, Spread-Spectrum 12V (for MAX5974A/MAX5974C, bring 2V, NDRV = AUXDRV = SS = COMP = unconnected, R GND EN TRANSCONDUCTANCE vs. TEMPERATURE 3.0 2.9 MAX5974C/MAX5974D 2.8 2.7 2.6 2.5 2.4 MAX5974A/MAX5974B 2.3 2.2 2.1 2.0 -40 - TEMPERATURE (°C) ENABLE RESPONSE 1ms/div SHUTDOWN RESPONSE 100µs/div Current-Mode PWM Controllers Typical Operating Characteristics (continued 21V for startup ...
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... Active-Clamped, Spread-Spectrum, Current-Mode PWM Controllers (V = 12V (for MAX5974A/MAX5974C, bring 2V, NDRV = AUXDRV = SS = COMP = unconnected, R GND EN V RAMP RESPONSE DCLMP MAX5974A/B/C/D toc35 V DCLMP 2V/div V NDRV 10V/div V AUXDRV 10V/div 10µs/div AUXDRV 10% TO 90% RISE TIME MAX5974A/B/C/D toc38 45.6ns V AUXDRV 2V/div 0ns 10ns/div ...
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... Connect to GND to disable frequency foldback. Transconductance Amplifier Output and PWM Comparator Input. COMP is level shifted down and 5 COMP connected to the inverting input of the PWM comparator. Current-Mode PWM Controllers CSSC MAX5974A 7 GND EN 14 MAX5974B MAX5974C DCLMP MAX5974D EP 5 ...
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Active-Clamped, Spread-Spectrum, Current-Mode PWM Controllers PIN NAME 6 FB Transconductance Amplifier Inverting Input 7 GND Signal Ground Current Sense with Slope Compensation Input. A resistor connected from CSSC to CS programs 8 CSSC the amount of slope compensation. See the ...
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Active-Clamped, Spread-Spectrum, Current-Mode PWM Controllers Block Diagrams 13 ...
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Active-Clamped, Spread-Spectrum, Current-Mode PWM Controllers 14 Block Diagrams (continued) ...
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... The features-rich devices are ideal for PoE IEEE 802.3af/at-powered devices. The MAX5974A/MAX5974C offer a 20V bootstrap UVLO wake-up level with a 13V wide hysteresis. The low startup and operating currents allow the use of a smaller storage capacitor at the input without compromising startup and hold times ...
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... UVLO. In this case, increase the value order to store enough energy to allow for the voltage at the tertiary winding to build up. While the MAX5974A/MAX5974B derive their input volt- age from the coupled inductor output during normal operation, the startup behavior is similar to that of the MAX5974C/MAX5974D ...
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Active-Clamped, Spread-Spectrum, startup to provide a slow and smooth increase of the duty cycle to its steady-state value. Calculate the value follows: SS × SS- where I (10FA typ) is the ...
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Active-Clamped, Spread-Spectrum, Current-Mode PWM Controllers Oscillator/Switching Frequency The ICs’ switching frequency is programmable between 100kHz and 600kHz with a resistor R between RT and GND. Use the following formula to determine the appropriate value of R erate the desired output-switching ...
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Active-Clamped, Spread-Spectrum, Frequency Foldback for High-Efficiency Light-Load Operation The frequency foldback threshold can be programmed from 0 to 20% of the full load current using a resistor from FFB to GND. The CS voltage is sampled during the NDRV on-time, ...
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... CSSC and CS used to program the ramp rate, and SYNC The MAX5974A/MAX5974B include an internal error amplifier with a sample-and-hold input. The feedback input of the MAX5974C/MAX5974D is continuously con- nected. The noninverting input of the error amplifier is connected to the internal reference and feedback is provided at the inverting input. High open-loop gain and unity-gain bandwidth allow good closed-loop bandwidth and transient response ...
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Active-Clamped, Spread-Spectrum, Typically, offline power supplies keep startup times to less than 500ms even in low-line conditions (85V AC input for universal offline or 36V DC for telecom applica- tions). Size the startup resistor maximum startup bias of ...
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... UVLO shutdown level T (7.5V max margin determined by the holdup time needed to “ride through” a brownout. Coupled-Inductor Feedback (MAX5974A/MAX5974B) When using coupled-inductor feedback, the power for the devices can be taken from the coupled inductor dur- ing the off-time. The voltage across the coupled induc- ...
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Active-Clamped, Spread-Spectrum 36V TO 57V 3.3mH C BULK 33µ 100kI C IN 1µF 25V R DCLMP1 IN 30. DCLMP2 750 I 1% DCLMP C SS 0.1µF SS MAX5974C R DT MAX5974D 16.9k ...
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... Active-Clamped, Spread-Spectrum, Current-Mode PWM Controllers V S 36V TO 57V C BULK 33µ 63V 100kI R DCLMP1 30. DCLMP2 750 I 1% DCLMP C SS 0.1µF SS MAX5974A R DT MAX5974B 16. (COUPLED INDUCTOR C DITHER FEEDBACK) 10nF DITHER/ SYNC R RT 14. FFB 10k I 1% FFB FB C COMP ...
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Active-Clamped, Spread-Spectrum BULK DCLMP1 EN R DCLMP2 DCLMP MAX5974C R MAX5974D DITHER C DITHER DITHER/ SYNC FFB FFB FB COMP R z GND ...
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Active-Clamped, Spread-Spectrum, Current-Mode PWM Controllers REVISION REVISION_ NUMBER DATE 0 6/10 Initial release Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the ...