MAX782 MAXIM [Maxim Integrated Products], MAX782 Datasheet
MAX782
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MAX782 Summary of contents
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... Other features include low-noise, fixed-frequency PWM operation at moderate to heavy loads and a synchroniz- able oscillator for noise-sensitive applications such as electromagnetic pen-based systems and communicat- ing computers. The MAX782 is a monolithic BiCMOS IC available in fine-pitch, SSOP surface-mount packages. _______________________Applications Notebook Computers Portable Data Terminals ...
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... VPPA, VPPB Current .........................................................100mA Continuous Power Dissipation (T SSOP (derate 11.76mW/°C above +70°C) ...................941mW Operating Temperature Ranges: MAX782CBX/MAX782__CBX ...............................0°C to +70°C MAX782EBX/MAX782__EBX ............................-40°C to +85°C Storage Temperature Range .............................-65°C to +160°C Lead Temperature (soldering, 10sec) .............................+300°C = 0mA, ON3 = ON5 = 5V, other digital input levels are 0V or +5V, T ...
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Controller for Notebook Computers ELECTRICAL CHARACTERISTICS (continued) (V+ = 15V, GND = PGND = 0V REF unless otherwise noted.) PARAMETER INTERNAL REGULATOR AND REFERENCE VL Output Voltage ON5 = ON3 = 0V, 5.5V < V+ < ...
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Triple-Output Power-Supply Controller for Notebook Computers __________________________________________Typical Operating Characteristics (Circuit of Figure 1, Transpower transformer type TTI5870, T EFFICIENCY vs. +5V OUTPUT CURRENT, 200kHz 100 10V 15V IN 80 COMPONENTS, ...
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Controller for Notebook Computers _____________________________Typical Operating Characteristics (continued) (Circuit of Figure 1, Transpower transformer type TTI5870, T PULSE-WIDTH MODULATION MODE WAVEFORMS HORIZONTAL = 500ns/div +5V OUTPUT CURRENT = 1A INPUT VOLTAGE = 16V +5V LOAD-TRANSIENT RESPONSE HORIZONTAL = 200 s/div ...
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Triple-Output Power-Supply Controller for Notebook Computers _____________________________Typical Operating Characteristics (continued) (Circuit of Figure 1, Transpower transformer type TTI5870, VDD ≥ 13V, T +5V LINE-TRANSIENT RESPONSE, RISING HORIZONTAL = 20 s/div LOAD +3.3V LINE-TRANSIENT RESPONSE, RISING HORIZONTAL = ...
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Controller for Notebook Computers ______________________________________________________________Pin Description PIN NAME 1 ON3 Logic input to turn on +3.3V. Logic high turns on the regulator. Connect to VL for automatic start-up. #1 level-translator/comparator noninverting input. Inverting comparator input is internally connected to 2 ...
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... Description The MAX782 converts a 5.5V to 30V input to five outputs (Figure 1). It produces two high-power, switch-mode, pulse-width modulated (PWM) supplies, one at +5V and the other at +3.3V. These two supplies operate at either 200kHz or 300kHz, allowing extremely small external components to be used. Output current capability ...
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... NOTE 1: BATTERY VOLTAGE RANGE 6.5V to 30V WITH COMPONENTS SHOWN SEE LOW-VOLTAGE (6-CELL) OPERATION SECTION. NOTE 2: SEE FIGURE 5. Figure 1. MAX782 Application Circuit The +3.3V supply is produced by a current-mode PWM step-down regulator using two small N-channel MOSFETs, a catch diode, an inductor, and a filter capacitor. Efficiency is greatly enhanced by the use of the second MOSFET (connected from LX3 to PGND), which acts as a synchronous rectifier ...
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... GND 4V 2.8V 300kHz/200kHz SYNC OSCILLATOR VPPA LINEAR DA0 REGULATOR DA1 VPPB LINEAR DB0 REGULATOR DB1 D3 1.65V D2 1.65V D1 1.65V VH Figure 2. MAX782 Block Diagram 10 ______________________________________________________________________________________ P 4.5V FAULT STANDBY ON VDD REG 13V TO 19V FB3 CS3 3.3V BST3 PWM CONTROLLER DH3 (SEE FIG. 3) LX3 DL3 SS3 ON PGND ON3 ...
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Controller for Notebook Computers 60kHz MAIN PWM REF, 3.3V COMPARATOR (OR INTERNAL 5V REFERENCE) SLOPE COMP MINIMUM CURRENT (IDLE-MODE) 25mV 4 A SS_ 3.3V ON_ N N –100mV VDD REG SINGLE-SHOT (SEE FIG. 2) Figure 3. PWM ...
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... Synchronous rectification allows for high efficiency by reducing the losses associated with the Schottky recti- fiers. Also, the synchronous rectifier MOSFETS are necessary for correct operation of the MAX782's boost gate-drive and VDD supplies. When the external power MOSFET N1 (or N2) turns off, energy stored in the inductor causes its terminal volt- age to reverse instantly ...
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Controller for Notebook Computers Boost Gate-Driver Supply Gate-drive voltage for the high-side N-channel switch is generated with a flying-capacitor boost circuit as shown in Figure 4. The capacitor is alternately charged from the VL supply via the diode and placed ...
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Triple-Output Power-Supply Controller for Notebook Computers High-Side Supply (VDD) The 15V VDD supply is obtained from the rectified and filtered secondary of transformer L2. VDD is enabled whenever the +5V supply is on (ON5 = high). The pri- mary and ...
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Controller for Notebook Computers The comparators are always active when V+ is above +4V, even when VH is 0V. Thus, Q1-Q3 will sink current to GND even when VH is 0V, but they will only source current from VH when ...
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Triple-Output Power-Supply Controller for Notebook Computers +5V Transformer (T1) Table 3 lists two commercially available transformers and parts for a custom transformer. The following instructions show how to determine the transformer parameters required for a custom design the ...
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... Controller for Notebook Computers FAT, HIGH-CURRENT TRACES MAIN CURRENT PATH KELVIN SENSE TRACES MAX782 Figure 5. Kelvin Connections for the Current-Sense Resistors MOSFETs with low gate-threshold voltage specifica- tions (i.e., maximum rather than 3V) are GS(TH) preferred, especially for high-current (5A) applications. Output Filter Capacitors (C6, C7, C14) The output filter capacitors determine the loop stability and output ripple voltage ...
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Triple-Output Power-Supply Controller for Notebook Computers Because this ramp is applied to the current-limit circuit, the actual time for the output voltage to ramp up depends on the load current and output capacitor value. Using Figure 1’s circuit with a ...
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... PD = gate driver loss = q GATE where VL is the MAX782’s logic supply voltage (nomi- nally 5V) and q G side and high-side switches. Note that gate charge losses are dissipated in the IC, not the MOSFETs, and therefore contribute to package temperature rise. ...
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... MOSFET (a data sheet parameter the switching frequency, and I is the peak current DRIVE available from the MAX782’s large high-side gate dri tput s (DH5 or DH3, approx imat A). Additional switching losses are introduced by other sources of stray capacitance at the switching node, ...
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... Figure 7. Power-Ready Signal Covers Both +3.3V and +5V Supplies with External Voltage Monitor IC (MAX707) Another approach uses the “power-ready” comparator output signal (see Figure 6) from one supply as a con- trol input to the ON_ pin of the other supply. MAX782 Q_ +5V POWER-READY 1.65V GND ...
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... On power-up, the Intel 486SL computer requires the +5V supply to come up before the +3.3V supply. A power-ready signal is required ≥50ms later. This circuit’s ON3 output connects to the MAX782’s ON3 pin, and can be wire-OR connected with an open- drain output to enable another circuit to turn the +3.3V supply off ...
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... VPP must deliver 120mA or more), see the MAX783 data sheet. This device is similar to the MAX782 except the +15V flyback winding controller has been shifted from the +5V side to the +3.3V side. ...
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... Even 100µA can do damage if left long enough. The complete power-supply system can be shut down by taking ON5 low, cutting the supply to the MAX782’s V+ pin, while the bootstrapped +5V supply is turned off. This removes the supply from the controller, and turns off all the supplies ...
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... Controller for Notebook Computers ________Evaluation Kit Information The MAX782 evaluation kit (EV kit assembled, surface-mount demonstration board. The kit embodies the standard application circuit and uses dip switches to control the 3V, 5V, and VPP outputs. The board accepts battery input voltages between 6.5V and 30V, and provides up to 30W of output power ...
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... Triple-Output Power-Supply Controller for Notebook Computers Figure 14. MAX782 EV Kit Schematic 26 ______________________________________________________________________________________ ...
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... Controller for Notebook Computers Figure 15. MAX782 EV Kit Top Component Layout and Silk Screen, Top View ______________________________________________________________________________________ Triple-Output Power-Supply 27 ...
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... Triple-Output Power-Supply Controller for Notebook Computers Figure 16. MAX782 EV Kit Ground Plane (Layers 2 and 3), Top View 28 ______________________________________________________________________________________ ...
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... Controller for Notebook Computers Figure 17. MAX782 EV Kit Top Layer (Layer 1), Top View ______________________________________________________________________________________ Triple-Output Power-Supply 29 ...
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... Triple-Output Power-Supply Controller for Notebook Computers Figure 18. MAX782 EV Kit, Bottom Component Layout and Silk Screen, Bottom View 30 ______________________________________________________________________________________ ...
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... Controller for Notebook Computers Figure 19. MAX782 EV Kit Bottom Layer (Layer 4), Top View ______________________________________________________________________________________ Triple-Output Power-Supply 31 ...
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... Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600 © 1994 Maxim Integrated Products _Ordering Information (continued) PART MAX782C/D LX3 MAX782EBX MAX782REBX BST3 MAX782SEBX DL3 EV KIT MAX782EVKIT-SO V+ 0.181" * Contact factory for dice specifications. VL (4.597mm) FB5 PGND DL5 BST5 LX5 H ...