19-1892; Rev 0; 1/01 High-Side Power Supply ____________________________Features ♦ +3.5V to +16.5V Operating Supply Voltage Range A +3.5V to +16.5V input supply range and a typical quiescent current of only 150µA make the MAX1822 ideal for a wide range of line- and battery-powered switching and control applications where efficiency is crucial. Also provided is a logic-level power-ready output (PR) to indicate when the high-side voltage reaches the proper level. The MAX1822 comes in an 8-pin SO package and requires three inexpensive external capacitors. The MAX1822 is a pin-for-pin replacement to the MAX622. ♦ Output Voltage Regulated to VCC + 11V (typ) ♦ 150µA (typ) Quiescent Current ♦ Power-Ready Output Ordering Information PART TEMP. RANGE PIN-PACKAGE MAX1822ESA -40°C to +85°C 8 SO ________________________Applications High-Side Power Control with N-Channel FETs Low-Dropout Voltage Regulators Power Switching from Low Supply Voltages H-Switches Stepper Motor Drivers Battery-Load Management Portable Computers Pin Configuration Typical Operating Circuit +3.5V TO +16.5V TOP VIEW 0.1µF CERAMIC 1 C1 7 6 C2 2 C1+ 8 VCC VOUT C1C2+ C2- C3 5 +12.5V TO +27.5V C1+ 1 C2- 2 8 VCC 7 C1- 3 6 C2+ GND 4 5 VOUT MAX1822 PR MAX1822 PR 3 GND 4 SO ________________________________________________________________ Maxim Integrated Products 1 For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. MAX1822 _______________General Description The MAX1822 high-side supply, using a regulated charge pump, generates a regulated output voltage 11V greater than the input supply voltage to power high-side switching and control circuits. The MAX1822 allows low-resistance N-channel MOSFETs (FETs) to be used in circuits that normally require costly, less efficient P-channel FETs and PNP transistors. The highside output also eliminates the need for logic FETs in +5V and other low-voltage switching circuits. MAX1822 High-Side Power Supply ABSOLUTE MAXIMUM RATINGS VCC ......................................................................................+17V VOUT ....................................................................................+30V IOUT ...................……………………………………………….25mA Continuous Total Power Dissipation (TA = +70°C) 8-pin SO (derate 5.88mW/°C above +70°C)...............471mW Operating Temperature Range ...........................-40°C to +85°C Storage Temperature Range .............................-65°C to +160°C Lead Temperature (soldering, 10s) .................................+300°C 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 (VCC = +5V, TA = TMIN to TMAX, unless otherwise noted.) PARAMETER Supply Voltage High-Side Voltage (Note 1) SYMBOL CONDITIONS VCC VOUT TYP 3.5 UNITS 16.5 V 11.5 12.5 16.5 IOUT = 0, VCC = 4.5V, C1 = C2 = 0.047µF, C3 = 1µF 14.5 15.5 17.5 IOUT = 0, VCC = 16.5V, C1 = C2 = 0.01µF, C3 = 1µF (Note 2) 26.5 27.5 29.5 IOUT = 50µA, VCC = 3.5V, C1 = C2 = 0.047µF, C3 = 1µF 8.5 10.5 16.5 IOUT = 250µA, VCC = 5V, C1 = C2 = 0.047µF, C3 = 1µF 15 18 26.5 29.5 V PRT IOUT = 0 (Note 3) 12 13.5 14.5 V Power-Ready Output High PROH ISOURCE = 100µA 3.8 4.3 5 V Power-Ready Output Low PROL ISINK = 1mA 0.4 V Output Voltage Ripple VR Switching Frequency FO Quiescent Supply Current IQ C1 = C2 = 0.01µF, C3 = 10µF, IOUT = 1mA, VCC = 16.5V 50 mV 90 kHz IOUT = 0, VCC = 5V, C1 = C2 = 0.047µF, C3 = 1µF, TA = +25°C 150 500 IOUT = 0, VCC = 16.5V, C1 = C2 = 0.047µF, C3 = 1µF, TA = +25°C 150 350 µA Note 1: High-side voltage measured with respect to ground. Note 2: For VCC > +13V on the MAX1822, use C1 = C2 = 0.01µF. Note 3: Power-Ready Threshold is the voltage with respect to ground at VOUT when PR switches high (PR = VCC). 2 MAX IOUT = 0, VCC = 3.5V, C1 = C2 = 0.047µF, C3 = 1µF IOUT = 500µA, VCC = 16.5V, C1 = C2 = 0.01µF, C3 = 1µF (Note 2) Power-Ready Threshold MIN _______________________________________________________________________________________ High-Side Power Supply C* = 0.01µF C* = 0.047µF C* = 0.022µF 250 200 150 VCC = +5V, IOUT = 0 TA = +25°C C1 = C2 = C* 100 C* = 0.1µF 50 1 2 3 4 5 6 7 9 200 150 100 50 1 10 2 3 4 5 6 7 8 9 C3 CAPACITOR VALUE (µF) MAX1822 SUPPLY CURRENT vs. SUPPLY VOLTAGE MAX1822 MAXIMUM OUTPUT CURRENT vs. C1 = C2 CAPACITOR VALUE IOUT = 0 C3 = 1µF TA = +25°C 1.2 1000 0.8 0.6 C1 = C2 = 0.01µF 0.4 800 700 600 500 400 300 NOTE: MAXIMUM IOUT IS THE LOAD CURRENT AT THE POINT WHERE VOUT BEGINS TO LOSE REGULATION. 200 C1 = C2 = 0.47µF 100 0 10 VCC = +5V C3 = 10µF TA = +25°C 900 MAXIMUM IOUT (µA) 1.0 0.2 0 6 8 10 12 14 16 18 0.01 C1 = C2 CAPACITANCE VALUE (µF) MAX1822 OUTPUT VOLTAGE vs. OUTPUT CURRENT MAX1822 OUTPUT VOLTAGE vs. OUTPUT CURRENT 17 VCC = +5V C3 = 10µF TA = +25°C 16 24 VCC = +12V C3 = 10µF TA = +25°C 23 C1 = C2 = 0.47µF 22 VOUT (V) 15 C1 = C2 0.047µF 21 C1 = C2 0.01µF 14 20 C1 = C2 = 0.22µF 13 0.1 VCC (V) MAX1822 toc05 4 MAX1822 toc05 2 VOUT (V) 250 C3 CAPACITOR VALUE (µF) 1.4 SUPPLY CURRENT (mA) 8 300 MAX1822 toc04 300 SUPPLY CURRENT (µA) C* = 0.033µF VCC = +16.5V IOUT = 0 TA = +25°C C1 = C2 = 0.01µF 350 MAX1822 toc03 SUPPLY CURRENT (µA) 350 400 MAX1822 toc01 400 MAX1822 toc02 MAX1822 SUPPLY CURRENT vs. C3 CAPACITOR VALUE MAX1822 SUPPLY CURRENT vs. C3 CAPACITOR VALUE C1 = C2 0.022µF 19 C1 = C2 = 0.01µF 18 12 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 IOUT (mA) 0 1 2 3 4 5 6 7 8 9 10 IOUT (mA) _______________________________________________________________________________________ 3 MAX1822 __________________________________________Typical Operating Characteristics High-Side Power Supply MAX1822 OUTPUT VOLTAGE RIPPLE vs. RESERVOIR CAPACITOR C3 TA = +25°C 180 VCC = +16.5V IOUT = 1mA C1 = C2 = 0.01µF 140 120 TURN-ON TIME (ms) VOUT RIPPLE (mV) 160 10 MAX1822 toc07 200 MAX1822 TURN-ON TIME vs. SUPPLY VOLTAGE 100 VCC = +5V IOUT = 500µA C1 = C2 = 0.047µF 80 60 IOUT = 0 TA = +25°C MAX1822 toc08 MAX1822 Typical Operating Characteristics (continued) 1 40 20 0 0.1 1 2 3 4 5 6 7 8 9 10 0 5 RESERVOIR CAPACITOR (µF) 10 15 20 VCC (V) Pin Description 4 PIN NAME 1 C1+ Positive terminal to primary charge-pump capacitor FUNCTION 2 C2- Negative terminal to secondary charge-pump capacitor 3 PR Power-Ready Output. High when VOUT is ≥ VCC + 8.5V with respect to GND. 4 GND Ground 5 VOUT High-Side Voltage Out 6 C2+ Positive terminal to secondary charge-pump capacitor 7 C1- Negative terminal to primary charge-pump capacitor 8 VCC Input Supply _______________________________________________________________________________________ High-Side Power Supply MAX1822 VOUT S8 11V POWER-READY COMPARATOR S7 C3 8.5V VINT RC OSCILLATOR + CONTROL LOGIC C2 S6 OVERVOLTAGE COMPARATOR S4 S3 VCC C1 S2 PR PR DRIVER S1 S5 GND TWO-STAGE CHARGE PUMP (SWITCHES SHOWN IN REFRESH MODE) Figure 1. MAX1822 Block Diagram Detailed Description Charge-Pump Operation The MAX1822 is a multistage charge-pump power supply. Although the charge pump is capable of multiplying VCC up to four times, the output is regulated to VCC + 11V by an internal feedback circuit for inputs above 4V. The charge pump typically operates at 90kHz, but regulates by pulse skipping. When VOUT exceeds VCC + 11V, the oscillator shuts off. As VOUT dips below VCC + 11V, the oscillator turns on. Power-Ready Output The Power-Ready Output (PR) signals control circuitry when the high-side voltage reaches a preset level. This feature can be used to protect external FET switches from excess dissipation and damage by preventing them from turning on, except when adequate gate drive levels are present. When power is applied, PR remains low until VOUT reaches approximately VCC + 8.5V. PR also goes low if VOUT falls below this level during operation, i.e., if the output is overloaded. The PR high level is VCC. Applications Information Quiescent Supply Current MAX1822 quiescent supply current varies with VCC and with the values of C1, C2, and C3 (Typical Operating Characteristics). Even with no external load, the device must still pump to overcome internal losses. Large ratios between C3 and C1 or C2 require more charge-pump cycles to restore VOUT. As VCC falls below 5V, quiescent current rises fairly rapidly to about 1mA at 4V (Typical Operating Characteristics). This rise occurs because VOUT no longer pulse skips to regulate at low input voltages; the oscillator runs continuously, so supply current is higher. Figure 2 shows the test circuit for the MAX1822 quiescent supply current. _______________________________________________________________________________________ 5 High-Side Power Supply MAX1822 Output Ripple C3 1.0µF VSUPPLY VOUT ripple is typically 50mVp-p with VCC = +5V, C1 and C2 = 0.047µF, and C3 = 1µF (Typical Operating Characteristics). Ripple can be reduced by increasing the ratio between the output storage capacitors C3 and C1 and C2. This is usually accomplished by increasing C3 and keeping C1 and C2 in the 0.01µF to 0.047µF range. For example, if C1 and C2 are 0.047µF (VCC must not exceed 13V) and C3 is 10µF, output ripple typically falls to 15mV (Typical Operating Characteristics). A C4 1000µF LOW ESR 1 C2 0.047µF 8 VCC C1+ 7 VOUT 5 C1- V 6 C2 0.047µF C2+ 2 MAX1822 C2- GND Capacitor Selection 4 Capacitor type is unimportant when selecting capacitors for the MAX1822. However, when VCC exceeds 13V, C1 and C2 must be no greater than 0.01µF. Using larger value capacitors with input voltages above 13V causes excessive amounts of energy to pass through Figure 2. MAX1822 Quiescent Supply-Current Test Circuit 6-CHANNEL LOAD SWITCH +5V C4 1µF 8 1 C2 0.047µF 7 6 C2 0.047µF 2 C1+ VCC VOUT C3 10µF ALL PULLUP RESISTORS = 1M 5 ALL TRANSISTORS = 1RF541 (NOTE 2) TO 1A LOAD C1C2+ C2- MAX1822 14 TO 1A LOAD 74C906 GND 4 2 1 4 3 6 5 8 9 10 11 TO 1A LOAD TO 1A LOAD SW1 SW2 TO 1A LOAD SW3 SW4 SW5 TO 1A LOAD SW6 13 12 ALL CAPACITORS = 1µF (NOTE 1) 7 NOTE 1: 1µF CAPACITORS SUPPRESS SWITCHING TRANSIENTS, SIZE DEPENDS ON LOAD CURRENTS. NOTE 2: POWER TRANSISTOR TYPE DEPENDS ON LOAD-CURRENT REQUIREMENTS. Figure 3. Single MAX1822 Driving Six High-Side Switches 6 _______________________________________________________________________________________ High-Side Power Supply MAX1822 H-BRIDGE MOTOR CONTROL +5V 14 V+ 8 1 C3 10µF VCC C1 C1 0.047µF VOUT 7 5 4 11 D1 S2 D2 S4 13 C2+ 9 C2- + DG303 6 C2 0.047µF 2 DC MOTOR +5V C1MAX1822 6 IRF541 IRF541 10 GND 4 IN1 S3 IN2 S1 GND 7 D3 3 – 5 IRF541 IRF541 D4 12 REVERSE FORWARD Figure 4. H-Bridge Motor Controller internal switches during charge-pump cycles. This may damage the device. high-side output current from the MAX1822 at a given supply voltage, calculated as follows: Output Protection The MAX1822 is not internally short-circuit protected. In applications where the output is susceptible to short circuit, external output short-circuit protection must be provided. Accomplish this by connecting a resistor between VOUT and the load to limit output current to less than 25mA. The resistor value is determined by the following formula: RCL ≥ VCC 25mA Typical Applications One MAX1822 Drives Six High-Side Switches Multiple subsystems or modules can be turned on and off using a single MAX1822 and an open-drain hex buffer such as the 74C906 (Figure 3). The drains of all buffer outputs are pulled through resistors to the MAX1822’s VOUT. The pullup resistance depends on the number of channels being used with the MAX1822 and power-dissipation limitations. The minimum pullup resistor value is determined by the number of channels paralleled on each high-side power supply and the RMIN = VOUT x (number of channels) IOUT where VOUT is the high-side output voltage and IOUT is the output current of the MAX1822. For example, assuming an output current of 1mA and six channels, as in Figure 3, the minimum pullup resistor value that will not excessively load the MAX1822 is about 100kΩ, assuming all six channels are pulled low at the same time. The value of the pullup resistor also affects the turn-on time of each FET, and hence the amount of energy dissipated in the FET during turn-on. The rate of rise of VGS is limited by the RC time constant of the pullup resistor and FET gate capacitance; waste power will be dissipated in the FET equal to (ILOAD)2 x rDS during the RC time period. H-Bridge Motor Driver An H-bridge motor driver is shown in Figure 4. The motor direction can be controlled by toggling between IN1 and IN2 of the DG303 analog switch. Each switch section turns on the appropriate FET pair, which passes current through the motor in the desired direction. _______________________________________________________________________________________ 7 MAX1822 High-Side Power Supply 4-CHANNEL LOAD SWITCH—NO PULLUP RESISTORS +3.5V TO +16.5V ALL TRANSISTORS = IRF541 (NOTE 1) TO LOAD C3 10µF C4 1µF 1 VCC C1+ VOUT 5 16 V+ TO LOAD 2 C1 0.01µF N01 7 9 12 C2+ 19 4 2 C2- 8 COM2 N02 C1MAX1822 6 C2 0.01µF 3 COM1 8 GND 4 7 14 17 MAX333 N03 TO LOAD N04 13 COM3 NC1 TO LOAD NC2 NC3 18 COM4 NC4 ALL CAPACITORS = 1µF (NOTE 2) 5 VIN1 NOTE 1: TRANSISTOR TYPE DEPENDS ON LOAD-CURRENT REQUIREMENTS. NOTE 2: 1µF CAPACITORS SUPRESS SWITCHING TRANSIENTS—VALUE DEPENDS ON LOAD CURRENT. IN2 1 10 IN3 11 IN4 20 SW1 SW2 SW3 SW4 Figure 5. MAX1822 Powering a MAX333 Quad Analog Switch, Realizing a 4-Channel Load Switch with No Pullup Resistors 4-Channel Load Switch with No Pullup Resistors Multiple high-side switches can be driven from a single MAX1822 high-side power supply with no pullup resistors on the FET gates. In Figure 5, a MAX1822 supplies high-side voltage to a MAX333 quad analog switch to control any one of four high-side switches. The FET gates are normally connected to ground when the MAX333 logic inputs are low. Low-Dropout Regulator In Figure 6, a MAX1822 high-side power supply powers an LM10 reference and op-amp combination, providing sufficient gate drive to turn on the FET. This allows the regulator to achieve less than 70mV dropout at 1A load using an IRF541, and just under 20mV for a SMP60N06. depends on the magnitude of the load change in the application and can be reduced or eliminated if the load remains relatively constant. With C6 = 1000µF, the output transient to a 1A load pulsed at 20Hz is typically less than 150mV. The regulator is turned on by applying VBATT to the Enable/Shutdown input and turned off by pulling this input to ground. The regulator output voltage, VOUT, is set by the ratio of R1 to R2, calculated as follows: V R2 = R1 OUT − 1 0.2 If the application does not require logic shutdown, connect the MAX1822 VCC pin directly to the battery and eliminate D2. The 200mV reference section is configured for a gain of 25 (e.g., 200mV x 25 = 5V) and connects to the noninverting input of the op amp; the regulator’s output connects directly to the inverting input. The op amp amplifies the error between its inputs and varies the gate drive to the FET, regulating the output. Capacitor C6 reduces transients due to load changes; its size 8 _______________________________________________________________________________________ High-Side Power Supply MAX1822 Fig 06 DROPOUT VOLTAGE vs. LOAD CURRENT 225 TA = +25°C 200 8 1 C1+ VCC C3 10µF VOUT C1 0.01µF 7 6 C1- MAX1822 PR VBATT 5 D1 R3 1k 3 1N914 R2 24k 3 C2+ 2 C2 0.01µF DROPOUT VOLTAGE (mV) C5 0.1µF 7 1 LM10 R1 8 6 1k Q1 IRF541 C2- GND 4 175 150 125 IRF541 100 75 SMP60N06 25 C6 1000µF IRFZ40 50 4 2 MAX1822 C4 0.1µF +5V 0 0.1 1 10 LOAD CURRENT (A) ENABLE/SHUTDOWN D2 1N914 Figure 6. Ultra-Low Dropout Positive Voltage Regulator with Logic-Controlled Enable/Shutdown. Chip Information TRANSISTOR COUNT: 158 _______________________________________________________________________________________ 9 ________________________________________________________Package Information SOICN.EPS MAX1822 High-Side Power Supply 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 right to change the circuitry and specifications without notice at any time. 10 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.