19-0186; Rev 2; 7/96 NUAL KIT MA ATION U EET L H A S V E TA WS DA FOLLO Low-Voltage Input, 3V/3.3V/5V/ Adjustable Output, Step-Up DC-DC Converters ____________________________Features ♦ 1V to 4.5V Input Guarantees Start-Up Under Load The devices include an Active RectifierTM that eliminates the need for an external catch diode, and permits regulation even when the input is greater than the output. Also, unlike those in other step-up converters, the MAX777L/MAX778L/MAX779L’s Active RectifierTM turns off in the shutdown mode, disconnecting the output from the source. This eliminates the current drain associated with conventional step-up converters when off or in shutdown. High-frequency operation (up to 150kHz) allows the use of small, surface-mount inductors with values of 10µH or less. Supply current is 190µA under no load and only 20µA in standby mode; supply voltage can range from 1V to 4.5V (1 to 3 cells). With a 2V input, the devices typically deliver 200mA at 5V, or 300mA at 3V. For fully specified devices designed for step-up/step-down applications (where the input can be above or below the output), refer to the MAX877L/MAX878L/MAX879L data sheet. ________________________Applications Single Battery-Cell (1V), Step-Up Voltage Conversion Efficient, High-Power Step-Up Regulation from Low Input Voltages Pagers Portable Instruments & Hand-Held Terminals Notebook and Palmtop Computers __________Typical Operating Circuit INPUT 1V TO 4.5V 22µF ♦ Load Fully Disconnected in Shutdown ♦ 82% Efficiency ♦ Output in Regulation with Input Voltage above Output Voltage ♦ Internal 1A Power Switch and Active Rectifier ♦ Adjustable Current Limit Allows Low-Cost Inductors ♦ 190µA No Load Supply Current ♦ 20µA Shutdown Supply Current ♦ 3V/3.3V (MAX778L), 5V (MAX777L), and Adjustable (MAX779L) Output Voltage ______________Ordering Information PART TEMP. RANGE MAX777LCPA 0°C to +70°C 8 Plastic DIP PIN-PACKAGE MAX777LCSA MAX777LC/D MAX777LEPA 0°C to +70°C 0°C to +70°C -40°C to +85°C 8 SO Dice* 8 Plastic DIP MAX777LESA MAX777LMJA -40°C to +85°C -55°C to +125°C 8 SO 8 CERDIP** Ordering Information continued at end of data sheet. * Dice are specified at TA = +25°C, DC parameters only. **Contact factory for availability and processing to MIL-STD-883. __________________Pin Configuration TOP VIEW 2 1 ON/OFF ♦ Up to 210mA Output 7 22µH IN ILIM MAX777L SHDN LX OUT 5 6 ILIM 1 IN 2 OUTPUT 5V AGND 3 MAX777L MAX778L MAX779L PGND 4 8 N.C. (MAX777L)* 7 SHDN 6 OUT 5 LX 100µF PGND 4 AGND 3 DIP/SO * SEL FOR MAX778L, FB FOR MAX779L. Active Rectifier is a trademark of Maxim Integrated Products. ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800 MAX777L/MAX778L/MAX779L _______________General Description The MAX777L/MAX778L/MAX779L are pulse-skipping DC-DC converters that step up from low-voltage inputs (1V guaranteed). They require only three external components—an inductor (typically 22µH) and two capacitors. The MAX777L delivers a 5V output, the MAX778L generates pin-selectable voltages of 3.0V or 3.3V, and the MAX779L output can be adjusted from 2.5V to 6V through an external resistive divider. MAX777L/MAX778L/MAX779L Low-Voltage Input, 3V/3.3V/5V/ Adjustable Output, Step-Up DC-DC Converters ABSOLUTE MAXIMUM RATINGS Supply Voltage (IN to PGND).......................................0V to 4.5V Output Short-Circuit Duration to PGND, AGND (Note 1)....30sec Voltage Applied to: LX (switch off) .......................................................-0.3V to 4.5V (switch on) ....................................30sec short to IN or OUT OUT, SHDN ...........................................................-0.3V to +7V FB ...........................................................-0.3V to (OUT + 0.3V) AGND to PGND ........................................................-0.3V, +0.3V Reverse Battery Current....................................................900mA Continuous Power Dissipation (TA = +70°C) Plastic DIP (derate 9.09mW/°C above +70°C) .............727mW SO (derate 5.88mW/°C above +70°C) ..........................471mW CERDIP (derate 8.00mW/°C above +70°C) ..................640mW Operating Temperature Ranges: MAX77_LC_A .......................................................0°C to +70°C MAX77_LE_A ....................................................-40°C to +85°C MAX77_LMJA .................................................-55°C to +125°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10sec) .............................+300°C Note 1: The output may be shorted to ground if the package power dissipation is not exceeded. Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VIN = +2.5V, ILOAD = 0mA, L = 22µH, COUT = 100µF, SHDN and ILIM connected to IN, AGND connected to PGND, TA = TMIN to TMAX, typical values are at TA = +25°C, unless otherwise noted.) PARAMETER Minimum Start-Up Voltage CONDITIONS ILOAD < 10mA, TA = +25°C (Note 2) Maximum Operating Voltage (Notes 2, 3) MAX778LC SEL = 0V MAX778LE MAX778LM Output Voltage MAX778L (Note 6) MAX778LC SEL = OPEN TYP MAX778LE MAX778LM ILOAD ≤ 30mA, 1.1V ≤ VIN ≤ 4.5V or ILOAD ≤ 140mA, 1.8V ≤ VIN ≤ 4.5V ILOAD ≤ 30mA, 1.2V ≤ VIN ≤ 4.5V or ILOAD ≤ 130mA, 1.8V ≤ VIN ≤ 4.5V ILOAD ≤ 25mA, 1.25V ≤ VIN ≤ 4.5V or ILOAD ≤ 120mA, 1.8V ≤ VIN ≤ 4.5V ILOAD ≤ 50mA, 1.1V ≤ VIN ≤ 3.3V or ILOAD ≤ 210mA, 1.8V ≤ VIN ≤ 3.3V ILOAD ≤ 50mA, 1.2V ≤ VIN ≤ 3.3V or ILOAD ≤ 200mA, 1.8V ≤ VIN ≤ 3.3V ILOAD ≤ 50mA, 1.25V ≤ VIN ≤ 3.3V or ILOAD ≤ 180mA, 1.8V ≤ VIN ≤ 3.3V ILOAD ≤ 50mA, 1.1V ≤ VIN ≤ 3V or ILOAD ≤ 210mA, 1.8V ≤ VIN ≤ 3V ILOAD ≤ 50mA, 1.2V ≤ VIN ≤ 3V or ILOAD ≤ 200mA, 1.8V ≤ VIN ≤ 3V ILOAD ≤ 40mA, 1.25V ≤ VIN ≤ 3V or ILOAD ≤ 180mA, 1.8V ≤ VIN ≤ 3V V 4.80 5.00 5.20 3.17 3.30 3.43 2.88 3.00 (Note 4) Efficiency ILOAD = 100mA 82 No-Load Supply Current ILOAD = 0mA (switch off) Shutdown Supply Current SHDN = 0V 2 V V Output Voltage Range (MAX779L) SHDN Input Current MAX UNITS 1 V 4.5 MAX777LC/ MAX779LC MAX777LE/ MAX779LE MAX777LM/ MAX779LM Output Voltage MAX777L/MAX779L (set to 5V) (Note 6) MIN 2.5 3.12 6.0 V 190 310 µA MAX77_LC, MAX77_LE 20 30 MAX77_LM 20 35 0V < SHDN < VIN 15 100 nA VIN < SHDN < 5V 12 40 µA _______________________________________________________________________________________ % µA Low-Voltage Input, 3V/3.3V/5V/ Adjustable Output, Step-Up DC-DC Converters (VIN = +2.5V, ILOAD = 0mA, L = 22µH, COUT = 100µF, SHDN and ILIM connected to IN, AGND connected to PGND, TA = TMIN to TMAX, typical values are at TA = +25°C, unless otherwise noted.) CONDITIONS PARAMETER MIN VIN = 1V to 4.5V SHDN Threshold VIN = 2.5V TYP MAX VIN/2 + 0.25 1.20 1.6 UNITS V SHDN Enable Delay 150 µs Current Limit 1.0 A -0.3 %/°C Current-Limit Temperature Coefficient Switch Saturation Voltage Maximum Switch On Time Minimum Switch Off Time Rectifier Forward Voltage Drop ISW = 400mA 0.275 ISW = 600mA 0.33 ISW = 1000mA 0.50 VIN = 2.5V 4.0 VIN = 1.8V 5.9 VIN = 1V 12.6 MAX777L, MAX779L 1.2 MAX778 2.2 ISW = 400mA 0.21 ISW = 600mA 0.31 ISW = 1000mA 0.50 Error-Comparator Trip Point MAX779L, over operating input voltage (Note 5) FB Pin Bias Current MAX779L, VFB = 0.3V 197.5 V µs µs V 202.5 207.5 mV 10 40 nA Switch Off Leakage Current 0.1 µA Rectifier Off Leakage Current 0.1 µA Note 2: Output in regulation, VOUT = VOUT (nominal) ±4%. Note 3: At high VIN to VOUT differentials, the maximum load current is limited by the maximum allowable power dissipation in the package (see Absolute Maximum Ratings). Note 4: Minimum value is production tested. Maximum value is guaranteed by design and is not production tested. Note 5: VOUT is set to a target value of +5V by 0.1% external feedback resistors. VOUT is measured to be 5V ±2.5% to guarantee the error comparator trip point. Note 6: Start-Up guaranteed under these load conditions. _______________________________________________________________________________________ 3 MAX777L/MAX778L/MAX779L ELECTRICAL CHARACTERISTICS (continued) __________________________________________Typical Operating Characteristics (Typical Operating Circuit, TA = +25°C, unless otherwise noted). 240 220 200 180 TA = +25°C 140 TA = -40°C 120 TA = 0°C 60 TA = +85°C 50 40 30 20 TA = 0°C 10 TA = -40°C 0 100 1 2 3 5 4 6 SUPPLY VOLTAGE (V) 3 2 4 5 6 MAX777-8 TA = +25°C 1.0 TA = -55°C 1 2 3 4 5 6 INPUT VOLTAGE (V) MAX778L EFFICIENCY vs. LOAD CURRENT 90 MAX777-1 VOUT = 5V VOUT = 3.3V OR 3.0V 80 EFFICIENCY (%) 80 EFFICIENCY (%) 1.5 INPUT VOLTAGE (V) 90 70 60 50 VIN = 4V VIN = 2.5V VIN = 1.8V VIN = 1.5V VIN = 1.1V 40 30 0.1 1 70 60 50 VIN = 2.5V VIN = 1.8V VIN = 1.5V VIN = 1.1V 40 10 100 30 0.1 1000 LOAD CURRENT (mA) 10 100 1000 MAX778L MAXIMUM OUTPUT CURRENT vs. INPUT VOLTAGE 350 MAX777-4 300 VOUT = 5V VOUT = 3.3V 300 OUTPUT CURRENT (mA) 250 200 150 100 50 0 0.5 1 LOAD CURRENT (mA) MAX777L/MAX779L MAXIMUM OUTPUT CURRENT vs. INPUT VOLTAGE OUTPUT CURRENT (mA) TA = +125°C 2.0 7 MAX777L/MAX779L EFFICIENCY vs. LOAD CURRENT 250 200 150 100 50 1.0 1.5 INPUT VOLTAGE (V) 4 2.5 0.5 1 7 3.0 MAX777-5 160 70 SHDN THRESHOLD VOLTAGE (V) TA = +85°C 3.5 MAX777-7 SHUTDOWN SUPPLY CURRENT (µA) (SWITCH = OFF) 260 80 MAX777-6 300 280 MAX778L SHDN THRESHOLD VOLTAGE vs. INPUT VOLTAGE AND TEMPERATURE SHUTDOWN SUPPLY CURRENT vs. INPUT VOLTAGE AND TEMPERATURE MAX777-2 NO-LOAD SUPPLY CURRENT vs. VOLTAGE AND TEMPERATURE NO-LOAD SUPPLY CURRENT (µA) MAX777L/MAX778L/MAX779L Low-Voltage Input, 3V/3.3V/5V/ Adjustable Output, Step-Up DC-DC Converters 2.0 2.5 0 0.5 1.0 1.5 INPUT VOLTAGE (V) _______________________________________________________________________________________ 2.0 7 Low-Voltage Input, 3V/3.3V/5V/ Adjustable Output, Step-Up DC-DC Converters LOAD-TRANSIENT RESPONSE LINE-TRANSIENT RESPONSE A A B B 2ms/div A: IOUT, 200mA/div, 0mA to 200mA B: VOUT, 50mV/div, AC COUPLED A: VIN, 1V/div, 1.8V to 3.3V B: VOUT, 100mV/div, AC-COUPLED, IOUT = 240mA MAX778L, VOUT = 3.3V, VIN = 2.5V MAX778L, VOUT = 3.3V 2ms/div SWITCHING WAVEFORMS, CONTINUOUS CONDUCTION SWITCHING WAVEFORMS, DISCONTINUOUS CONDUCTION A A B B 0mA C C 5µs/div 2µs/div A: SWITCH VOLTAGE (LX PIN), 2V/div B: INDUCTOR CURRENT, 0.5A/div C: OUTPUT VOLTAGE RIPPLE, 50mV/div, AC COUPLED A: SWITCH VOLTAGE (LX PIN), 2V/div B: INDUCTOR CURRENT, 0.5A/div C: OUTPUT VOLTAGE RIPPLE, 50mV/div, AC COUPLED MAX777L, VIN = 1.5V, IOUT = 100mA MAX777L, VIN = 3V, IOUT = 70mA _______________________________________________________________________________________ 5 MAX777L/MAX778L/MAX779L _____________________________Typical Operating Characteristics (continued) (Circuit of Figure 1, TA = +25°C, unless otherwise noted.) MAX777L/MAX778L/MAX779L Low-Voltage Input, 3V/3.3V/5V/ Adjustable Output, Step-Up DC-DC Converters _____________________________Typical Operating Characteristics (continued) (Circuit of Figure 1, TA = +25°C, unless otherwise noted.) MAX778L START-UP TIME A B 10ms/div A: SHDN, 2V/div B: VOUT, 1V/div VOUT = 3V ______________________________________________________________Pin Description PIN NAME 1 ILIM 2 IN 3 AGND Analog ground. Not internally connected to PGND. 4 PGND Power ground. Must be low impedance; solder directly to ground plane or star ground. Connect to AGND, close to the device. 5 LX 6 OUT 7 SHDN 8 6 FUNCTION Sets switch current-limit input. Connect to IN for 1A current limit. A resistor from ILIM to IN sets lower peak inductor currents. Input from battery Collector of 1A NPN power switch and emitter of Active Rectifier PNP. Voltage output. Connect filter capacitor close to pin. Shutdown input disables power supply when low. Also disconnects load from input. Threshold is set at VIN/2. N.C. (MAX777L) No connect—not internally connected. SEL (MAX778L) Selects the main output voltage. 3.3V when hard-wired to AGND, 3.0V when left open. FB (MAX779L) Feedback input for adjustable-output operation. Connect to an external voltage divider between VOUT and AGND. _______________________________________________________________________________________ Low-Voltage Input, 3V/3.3V/5V/ Adjustable Output, Step-Up DC-DC Converters MAX777L/MAX778L/MAX779L 22µH VIN 100µF RLIM 2 1 IN LX ILIM DELAY TIMER tOFF ACTIVE RECTIFIER OUT 6 SWITCH DRIVER DELAY TIMER tON VOUT 100µF RECTIFIER CONTROL PGND 4 1 : N MAX778L SEL 8 VREF 7 SHDN 0.2025V SHUTDOWN CONTROL AGND 3 Figure 1. MAX778L Block Diagram _______________Detailed Description Operating Principle The MAX777L/MAX778L/MAX779L combine a switchmode regulator with an NPN bipolar switch, current limit, precision voltage reference, and active rectifier— all in a single monolithic device. In shutdown mode, the internal rectifier is completely turned off and disconnects the load from the source. Only two external components are required in addition to the input bypass capacitor: a 22µH inductor and a 100µF filter capacitor. A minimum off-time, current-limited, pulse-frequencymodulation (PFM) control scheme combines the advantages of pulse width modulation (PWM) (high output power and efficiency) with those of a traditional PFM pulse skipper (low quiescent currents). External conditions (inductor value, load, and input voltage) determine the way the converter operates, as follows: At light loads, the current through the inductor starts at zero, rises to a peak value, and drops down to zero in each cycle (discontinuous-conduction mode). In this case, the switching frequency is governed by a pair of one-shots that set a maximum on-time inversely proportional to VIN [tON = 8.8/(VIN - 0.25)] and a minimum offtime (1.3µs for MAX777L/MAX779L and 2.3µs for MAX778L). With a 22µH inductor, LX’s peak current is about 400mA and is independent of input voltage. Efficiency at light loads is improved because of lower peak currents. At very light loads, more energy is stored in the coil than is required by the load in each cycle. The converter regulates by skipping entire cycles. Efficiency is typically 65% to 75% in the pulse-skipping mode. Pulse-skipping waveforms can be irregular, and the output waveform contains a low-frequency component. Larger, low equivalent series resistance (ESR) filter capacitors can help reduce the ripple voltage if needed. _______________________________________________________________________________________ 7 Step-Down Mode If the input voltage exceeds the output voltage, the MAX777L/MAX778L/MAX779L behave as “switched” linear regulators. If the output voltage starts to drop, the switch turns on and energy is stored in the coil, as in normal step-up mode. After the switch turns off, the voltage at LX flies high. The active rectifier turns on when LX rises above VIN. As in a linear regulator, the voltage difference between V IN and V OUT appears across the rectifier (actually a PNP transistor) until the current goes to zero and the rectifier turns off. At high VIN to VOUT differentials, the maximum load current is limited by the maximum allowable power dissipation in the package. For fully specified buck/boost converters, refer to the data sheet for the pin-compatible MAX877L/MAX878L/MAX879L. Active Rectifier The internal active rectifier of the MAX777L/MAX778L/ MAX779L replaces the external Schottky catch diode in normal boost operation. The rectifier consists of a PNP pass transistor and a unique control circuit which, in shutdown mode, entirely disconnects the load from the source. This is a distinct advantage over standard boost topologies, since it prevents battery drain in shutdown. The active rectifier also acts as a zero-dropout regulator if the input exceeds the regulated output. This allows the MAX777L/MAX778L/MAX779L to act as buck/boost 8 converters. Useful in battery-powered applications, where the battery voltage may initially exceed the output voltage, the converters will regulate down to the output voltage and seamlessly switch into boost mode as the input drops below the output voltage. The pin-compatible MAX877L/MAX878L/MAX879L are fully specified buck/boost converters with higher specified output currents than the MAX777L/MAX778L/MAX779L. Shutdown Shutdown (SHDN) is a high-impedance, active-low input. Connect SHDN to V IN for normal operation. Keeping SHDN at ground holds the converters in shutdown mode. Since the active rectifier is turned off in shutdown mode, the path from input to load is cut, and the output effectively drops to 0V. The supply current in the shutdown state ranges from 4µA at VIN = 1V to 50µA at VIN = 4.5V. The shutdown circuit threshold is set nominally to VIN/2 + 250mV. When SHDN is below this threshold, the device is shut down and is enabled with SHDN above the threshold. When driven from external logic, SHDN can be driven to a higher voltage than VIN. Current Limit Connecting ILIM to IN sets an LX current limit of 1A. For smaller output power levels that do not require the maximum peak current, the peak inductor current can be reduced to optimize overall efficiency and to allow very small, low-cost coils with lower current ratings. See also the Inductor Selection section. Reduce the MAX777L/MAX778L/MAX779L peak inductor current by connecting a resistor between ILIM and IN. See Figure 2 to select the resistor. CURRENT-LIMIT RESISTOR vs. PEAK INDUCTOR CURRENT 1200 MAX777-FG02 At heavy loads above approximately 100mA, the converter enters continuous-conduction mode, where current always flows in the inductor. The switch-on state is controlled cycle-by-cycle by either the maximum t ON time or the switch’s preset current limit. As a result, the switch's current rating is not exceeded and the inductor is not saturated. At very heavy loads, the inductor current self-oscillates between this peak current limit and some lower value governed by the minimum off-time, the inductance value, and the input/output differential. With ILIM shorted to IN, the peak switch current of the internal NPN power switch is set to 1A. The peak switch current can be set to a lower value by connecting a resistor between ILIM and IN (see Current Limit section). This enables the use of physically smaller inductors with lower saturation-current ratings. At 1A, the switch voltage drop (V SW ) is about 500mV. V SW decreases to about 250mV at 0.1A. Conventional PWM converters generate constant-frequency switching noise, while this architecture produces variable-frequency switching noise. However, the noise does not exceed the current limit times the filter-capacitor ESR, unlike conventional pulse-skippers. PEAK INDUCTOR CURRENT (mA) MAX777L/MAX778L/MAX779L Low-Voltage Input, 3V/3.3V/5V/ Adjustable Output, Step-Up DC-DC Converters 1000 800 600 400 VIN = 2.5V 200 0 0 2 4 6 8 10 12 RESISTOR VALUE (kΩ) Figure 2. Current-Limit Resistor vs. Current Limit _______________________________________________________________________________________ 14 Low-Voltage Input, 3V/3.3V/5V/ Adjustable Output, Step-Up DC-DC Converters VIN C1 22µF 5 2 7 1 LX IN OUT MAX779L 3 VOUT C3 R1 SHDN ILIM AGND 6 FB C2 100µF 8 PGND 4 R2 Figure 3. MAX779L Adjustable Voltage Output Voltage Selection The output voltage of the MAX777L is fixed at 5V. The MAX778L output voltage can be set to 3V by leaving the SEL pin open. Connect SEL to AGND for 3.3V operation. The MAX779L’s output voltage is set by two resistors, R1 and R2 (Figure 3), which form a voltage divider between the output and the FB pin. The output voltage can be set from 2.5V to 6.0V by the equation: VOUT = (0.2025) [(R1 + R2)/R2] To simplify the resistor selection: R1 = (R2)[(VOUT/0.2025) - 1] Since the input current at FB is 40nA maximum, large values (10kΩ to 50kΩ for R2) can be used with no significant loss of accuracy. For 1% error, the current through R2 should be at least 100 times FB’s bias current. When large values are used for the feedback resistors (R1 > 50kΩ), stray output impedance at FB can add “lag” to the feedback response, destabilizing the regulator and creating a larger ripple at the output. Lead lengths and circuit board traces at the FB node should be kept short. Reduce ripple by adding a “lead” compensation capacitor (C3, 100pF to 50nF) in parallel with R1. __________Applications Information The Typical Operating Circuit shows a MAX777L stepup application circuit. This circuit starts up and operates with inputs ranging from 1.0V to 4.5V. Start-up time is a function of the load, typically less than 5ms. Output current capability is a function of the input voltage. See Typical Operating Characteristics. The 22µH inductor shown in the Typical Operating Circuit is sufficient for most MAX777L/MAX778L/ MAX779L designs. Other inductor values ranging from 10µH to 47µH are also suitable. The inductor should have a saturation rating equal to or greater than the peak switch-current limit, which is 1A without an external current limit (ILIM connected to IN). It is acceptable to operate the inductor at 120% of its saturation rating; however, this will reduce efficiency. For highest efficiency, use an inductor with a low DC resistance, preferably under 0.2Ω. Table 1 lists suggested inductor suppliers. Capacitor Selection The 100µF, 10V surface-mount tantalum (SMT) output capacitor shown in the Typical Operating Circuit will provide a 20mV output ripple or less, stepping up from 2V to 3.3V at 200mA. Smaller capacitors, down to 10µF, are acceptable for light loads or in applications that tolerate higher output ripple. The input capacitor may be omitted if the input lead length is less than 2 inches (5cm) or if the loads are small. The primary factor in selecting both the output and input filter capacitor is low ESR. The ESR of both bypass and filter capacitors affects efficiency. Optimize performance by increasing filter capacitors or using specialized low-ESR capacitors. The smallest low-ESR SMT tantalum capacitors currently available are Sprague 595D or 695D series. Sanyo OS-CON organic semiconductor through-hole capacitors also exhibit very low ESR, are rated for the wide temperature range, and are particularly useful for operation at cold temperatures. Table 1 lists suggested capacitor suppliers. Layout The MAX777L/MAX778L/MAX779L’s high peak currents and high-frequency operation make PC layout important for minimum ground bounce and noise. Locate input bypass and output filter capacitors close to the device pins. All connections to the FB pin (MAX779L) should also be kept as short as possible. A ground plane is recommended. Solder AGND (pin 3) and PGND (pin 4), directly to the ground plane. Refer to the MAX777L/MAX778L/MAX779L evaluation kit (EV kit) manual for a suggested surface-mount layout. _______________________________________________________________________________________ 9 MAX777L/MAX778L/MAX779L Inductor Selection LI 22µH MAX777L/MAX778L/MAX779L Low-Voltage Input, 3V/3.3V/5V/ Adjustable Output, Step-Up DC-DC Converters Table 1. Component Suppliers PRODUCTION METHOD INDUCTORS Sumida CD54-220 (22µH) CAPACITORS Sprague 595D Sprague 695D Murata-Erie LQHYN1501K04M00-D5 (15µH) Matsuo 267 series Coiltronics CTX20-1 AVX TPS series Miniature Through-Hole Sumida RCH654-220 Sanyo OS-CON low-ESR organic semiconductor Low-Cost Through-Hole Coilcraft PCH-27-223 Surface Mount AVX USA: Coiltronics Matsuo Murata-Erie USA: USA: USA: Nichicon Sanyo USA: USA: Japan: USA: USA: Japan: USA: Sprague Sumida United Chemi-Con 10 Nichicon PL series low-ESR electrolytic United Chemi-Con, LXF series (803) 946-0690 (800) 282-4975, FAX (803) 626-3123 (561) 241-7876, FAX (561) 241-9339 (714) 969-2491, FAX (714) 960-6492 (814) 237-1431 (800) 831-9172, FAX (814) 238-0490 (847) 843-7500 (619) 661-6835, FAX (847) 843-2798 (81) 7-2070-6306, FAX (81) 7-2070-1174 (603) 224-1961, FAX (603) 224-1430 (847) 956-0666, FAX (847) 956-0702 (81) 3-3607-5111, FAX (81) 3-3607-5144 (714) 255-9500, FAX (714) 255-9400 ______________________________________________________________________________________ Low-Voltage Input, 3V/3.3V/5V/ Adjustable Output, Step-Up DC-DC Converters PART TEMP. RANGE MAX778LCPA 0°C to +70°C 8 Plastic DIP MAX778LCSA MAX778LC/D MAX778LEPA 0°C to +70°C 0°C to +70°C -40°C to +85°C 8 SO Dice* 8 Plastic DIP MAX778LESA MAX778LMJA MAX779LCPA MAX779LCSA MAX779LC/D MAX779LEPA -40°C to +85°C -55°C to +125°C 0°C to +70°C 0°C to +70°C 0°C to +70°C -40°C to +85°C 8 SO 8 CERDIP** 8 Plastic DIP 8 SO Dice* 8 Plastic DIP MAX779LESA MAX779LMJA -40°C to +85°C -55°C to +125°C 8 SO 8 CERDIP** ___________________Chip Topography PIN-PACKAGE * Dice are specified at TA = +25°C, DC parameters only. **Contact factory for availability and processing to MIL-STD-883. ILIM VREF FB IN SHDN 0.084" (2.134mm) AGND OUT PGND LX 0.068" (1.727mm) TRANSISTOR COUNT: 170; SUBSTRATE CONNECTED TO AGND. ______________________________________________________________________________________ 11 MAX777L/MAX778L/MAX779L _Ordering Information (continued) MAX777L/MAX778L/MAX779L Low-Voltage Input, 3V/3.3V/5V/ Adjustable Output, Step-Up DC-DC Converters ________________________________________________________Package Information D E DIM E1 A A1 A2 A3 B B1 C D1 E E1 e eA eB L A3 A A2 L A1 0° - 15° C e B1 eA B eB D1 Plastic DIP PLASTIC DUAL-IN-LINE PACKAGE (0.300 in.) INCHES MAX MIN 0.200 – – 0.015 0.175 0.125 0.080 0.055 0.022 0.016 0.065 0.045 0.012 0.008 0.080 0.005 0.325 0.300 0.310 0.240 – 0.100 – 0.300 0.400 – 0.150 0.115 PKG. DIM PINS P P P P P N D D D D D D 8 14 16 18 20 24 INCHES MIN MAX 0.348 0.390 0.735 0.765 0.745 0.765 0.885 0.915 1.015 1.045 1.14 1.265 MILLIMETERS MIN MAX – 5.08 0.38 – 3.18 4.45 1.40 2.03 0.41 0.56 1.14 1.65 0.20 0.30 0.13 2.03 7.62 8.26 6.10 7.87 2.54 – 7.62 – – 10.16 2.92 3.81 MILLIMETERS MIN MAX 8.84 9.91 18.67 19.43 18.92 19.43 22.48 23.24 25.78 26.54 28.96 32.13 21-0043A DIM D 0°-8° A 0.101mm 0.004in. e B A1 E 12 C H L Narrow SO SMALL-OUTLINE PACKAGE (0.150 in.) A A1 B C E e H L INCHES MAX MIN 0.069 0.053 0.010 0.004 0.019 0.014 0.010 0.007 0.157 0.150 0.050 0.244 0.228 0.050 0.016 DIM PINS D D D 8 14 16 MILLIMETERS MIN MAX 1.35 1.75 0.10 0.25 0.35 0.49 0.19 0.25 3.80 4.00 1.27 5.80 6.20 0.40 1.27 INCHES MILLIMETERS MIN MAX MIN MAX 0.189 0.197 4.80 5.00 0.337 0.344 8.55 8.75 0.386 0.394 9.80 10.00 ______________________________________________________________________________________ 21-0041A