MAX771 Maxim Integrated Products, MAX771 Datasheet

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... The MAX770/MAX771/MAX772 accept input voltages from 2V to 16.5V. Output voltages are preset at 5V, (MAX770), 12V (MAX771), and 15V (MAX772); they can also be adjusted using two resistors. The MAX773 accepts inputs from 3V to 16.5V. For a wider input range, it features an internal shunt regulator that allows unlimited higher input voltages. The MAX773’ ...

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... MAX770–772 (internal feedback resistors) MAX770–772C/E (external resistors) MAX770–772MJA (external resistors) MAX773C/E MAX773MJD MAX770/MAX771/MAX772 V+ = 16.5V, SHDN = 0V (normal operation 10.0V, SHDN ≥ 1.6V (shutdown 16.5V, SHDN ≥ 1.6V (shutdown 2.0V to 5.0V, over full load range V+ = 2.0V to 12.0V, over full load range ...

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Adjustable, High-Efficiency, ELECTRICAL CHARACTERISTICS (continued) ( 0mA LOAD A MIN PARAMETERS SYMBOL REF Load Regulation REF Line Regulation FB Trip-Point Voltage V FB Input Current I SHDN Input High ...

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... SUPPLY CURRENT vs. SUPPLY VOLTAGE 0 12V OUT 0.6 BOOTSTRAPPED CIRCUIT OF FIGURE 2b 0.4 0.2 NON-BOOTSTRAPPED CIRCUIT OF FIGURE SUPPLY VOLTAGE (V) MAX772 EFFICIENCY vs. OUTPUT CURRENT (BOOTSTRAPPED) 100 V = 15V, CIRCUIT OF FIGURE 2b OUT MAX772 SUBSTITUTED FOR MAX771 12V 0.001 0.01 0.1 1 OUTPUT CURRENT (A) MAX771 LOAD CURRENT vs. ...

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Adjustable, High-Efficiency, ____________________________Typical Operating Characteristics (continued +25°C, unless otherwise noted.) A REFERENCE OUTPUT RESISTANCE vs. TEMPERATURE 250 200 150 100 50 0 -60 -40 - TEMPERATURE ( C) MAXIMUM SWITCH ON-TIME vs. TEMPERATURE 16.5 ...

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Adjustable, High-Efficiency, Low I , Step-Up DC-DC Controllers Q ____________________________Typical Operating Characteristics (continued) (Circuit of Figure 2a +25°C, unless otherwise noted.) A MAX770 HEAVY-LOAD SWITCHNG WAVEFORMS V OUT 0 I LIM I LIM ...

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... EXT Gate drive for external N-channel power transistor Power-supply input. Also acts as a voltage-sense point when in bootstrapped mode for the MAX770/MAX771/MAX772 shunt regulator when SGND is connected to ground for the MAX773. Bypass to SGND with 0.1 F when using the shunt regulator. Feedback input for adjustable-output operation. Connect to ground for fixed-output operation. Use ...

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... The minimum input voltage for the MAX770–MAX773 is 3V when using external feedback resistors. With supply voltages below 5V, bootstrapped mode is recommended. Note: When using the MAX770/MAX771/MAX772 in non-bootstrapped mode, there is no preset output operation because V+ is also the output voltage sense point for fixed-output operation. External resistors must be used to set the output voltage ...

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... MAX773 use a sense resistor to control the peak induc- tor current. They also operate with high switching MAX770–MAX773 SHDN BIAS CIRCUITRY MAX770 MAX771 MAX772 SGND EXTH 2.5V MAX773 ONLY EXTL 0.1V EXT MAX770 MAX771 MAX772 CS External Power-Transistor Control Circuitry PFM Control Scheme 9 ...

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... When the power switch REF MAX771 SHDN 1N5817 EXT Si9410DY 8 AGND SENSE GND 100m 200 REF 1N5817 MAX770 SHDN EXT 100 F MAX771 Si9410DY MAX772 8 AGND SENSE 140k 3 FB GND R1 7 28k OUT ) -1 V REF = 12V OUT @ 0. OUT ...

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Adjustable, High-Efficiency V12 14 V15 SGND R4 8 63.4k REF MAX773 (1 LBO 0 LBI 13 EXTH EXTL SHDN 10k ...

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... V = 1.5V REF Figure 4. MAX773 Shunt Regulator The MAX770/MAX771/MAX772 feature a low input volt- age start-up oscillator that guarantees start-up with no load down to 2V when operating in bootstrapped mode and using internal feedback resistors. At these low volt- ages, the supply voltage is not large enough for proper error-comparator operation and internal biasing ...

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... If a decaying voltage source (such as a battery) is used, see the additional notes in the Low Input Voltage Operation section. Use the MAX770/MAX771/MAX772 unless one or more of the following conditions applies. If one or more of the following is true, use the MAX773 NPN power transistor will be used as the power ...

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... This provides adequate biasing SHUNT current for this circuit, although higher shunt currents can be used. ______________________________________________________________________________________ 14 BOOTSTRAPPED* GND to V OUT Lower Higher Higher 2V to 16.5V (MAX770/MAX771/MAX772), (internal feedback resistors 16.5V (MAX770/MAX771/MAX772), (external feedback resistors 16.5V (MAX773 (MAX770/MAX771/MAX772 (MAX773) MAX770–MAX773(N) MAX770–MAX773( SHUNT V+ ...

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Adjustable, High-Efficiency, 3 OUT 3 40m SENSE 2 50m SENSE 2.0 R SENSE 1.5 1.0 R SENSE 0.5 R SENSE INPUT VOLTAGE (V) Figure ...

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... L Table 2 lists inductor suppliers and specific recom- mended inductors. N Use an N-channel MOSFET power transistor with the MAX770/MAX771/MAX772 (Figure 8a). Use an N-FET whenever possible with the MAX773. An NPN transistor can be used, but be extremely careful R SENSE when determining the base current (see NPN Transistors section) ...

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Adjustable, High-Efficiency, The two most significant losses contributing to the 2 N-FET’s power dissipation are I R losses and switching losses. Select a transistor with low minimize these losses. RSS Determine the maximum required gate-drive ...

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Adjustable, High-Efficiency, Low I , Step-Up DC-DC Controllers Q Smaller capacitors are acceptable for light loads or in applications that can tolerate higher output ripple. Since the output filter capacitor’s ESR affects efficien- cy, use low-ESR capacitors for ...

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Adjustable, High-Efficiency, Starting Up under Load The Typical Operating Characteristics show the Start- Up Voltage vs. Load Current graph for bootstrapped- mode operation. This graph depends on the type of power switch used. The MAX770–MAX773 are not designed ...

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... MAX771CPA 0°C to +70°C MAX771CSA 0°C to +70°C MAX771C/D 0°C to +70°C MAX771EPA -40°C to +85°C MAX771ESA -40°C to +85°C MAX771MJA -55°C to +125°C MAX772CPA 0°C to +70°C MAX772CSA 0°C to +70°C MAX772C/D 0°C to +70°C MAX772EPA -40°C to +85°C MAX772ESA -40° ...