+12V, 30mA Flash Memory Programming Supply MAX662A

1 _____General DescriptionThe MAX662A is a regulated +12V, 30mA-output, charge- pump dc -DC converter . It provides the necessary +12V 5% output to program byte-wide Flash memories, andrequires no inductors to deliver a guaranteed 30mA out-put from inputs as low as It fits into less than board space. The MAX662A is a pin-compatibleupgrade to the MAX662, and is recommended for newdesigns. The MAX662A offers lower quiescent and shut-down currents, and guarantees the output current over alltemperature MAX662A is the first charge-pump boost converter toprovide a regulated +12V output. It requires only a fewinexpensive capacitors, and the entire circuit is complete-ly logic-controlled shutdown pin that interfaces directlywith microprocessors reduces the Supply current to A.

2 The MAX662A comes in 8-pin narrow SO and DIPpackages. For higher-current Flash Memory Programming solutions,refer to the data sheets for the MAX734 (120mA outputcurrent, guaranteed) and MAX732 (200mA output cur-rent, guaranteed) PWM, switch-mode DC-DC , refer to the MAX761 data sheet for a 150mA, PFMswitch-mode DC-DC converter that operates from inputsas low as +12V Flash Memory Programming SuppliesCompact +12V Op-Amp SuppliesSwitching MOSFETs in Low-Voltage SystemsDual-Output +12V and +20V Supplies_____Features regulated +12V 5% Output Voltage to Supply Voltage Range Fits in Guaranteed 30mA Output No Inductor Uses Only 4 Capacitors 185 A Quiescent Current Logic-Controlled A Shutdown 8-Pin Narrow SO and DIP Packages_____Ordering InformationMAX662A+12V.

3 30mA Flash MemoryProgramming Supply_____Maxim Integrated Products112348765 SHDNGNDVOUTVCCC2+C2-C1+C1-MAX662 ADIP/SOTOP VIEW_____Pin ConfigurationMAX662 AFLASH FOUTPUT 12V 5% 30mAVCCSHDNC1+C1-VOUTC2-C2+GNDINPUT TO Operating CircuitCall toll free 1-800-998-8800 for free samples or ; Rev 1; 8/94 EVALUATION KIT MANUALFOLLOWS DATA SHEETPARTMAX662 ACPAMAX662 ACSAMAX662AC/D0 C to +70 C0 C to +70 C0 C to +70 CTEMP. RANGEPIN-PACKAGE8 Plastic DIP8 SODice*MAX662 AEPA-40 C to +85 C8 Plastic DIPMAX662 AESA-40 C to +85 C8 SOMAX662 AMJA-55 C to +125 C8 CERDIP** Dice are tested at TA= +25 C.** Contact factory for availability and processing to +12V, 30mA Flash MemoryProgramming Supply2_____ABSOLUTE MAXIMUM RATINGSELECTRICAL CHARACTERISTICS(Circuit of Figure 3a, VCC= to , TA= TMINto TMAX, unless otherwise noted.)

4 Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functionaloperation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure toabsolute maximum rating conditions for extended periods may affect device GND .. to to (VCC+ ) Power Dissipation (TA= +70 C)Plastic DIP (derate C above +70 C) ..727mWSO (derate C above +70 C) ..471mWCERDIP (derate C above +70 C) ..640mWOperating Temperature RangesMAX662AC_A ..0 C to +70 CMAX662AE_A ..-40 C to +85 C to +125 CStorage Temperature Range.

5 -65 C to +160 CLead Temperature (soldering, 10sec) ..+300 CMAX662AC/EVCC= VSHDN= 5V,IOUT= 30mAVCC= 5V, IOUT= 30mAMAX662 AMNo load, VSHDN= 0 VNo load, VSHDN= VCCVCC= VSHDN= 5 VVCC= 5V, IOUT= 30mAVCC= 5V, VSHDN= 0 VCONDITIONS A0 SHDN Pin Input 12 RSWVCC-to-VOUTS witch Impedance%76 Power Voltage A185500 ICCS upply Current CurrentkHz500fOSCO scillator FrequencyUNITSMINTYPMAXSYMBOLPARAMETER__ ___Typical Operating Characteristics(Circuit of Figure 3a, TA = +25 C, unless otherwise noted.) Supply CURRENT vs. Supply VOLTAGE140300 MAX662A -01 Supply VOLTAGE (V) Supply CURRENT ( A) = -55 CTA = 0 CTA = +25 CTA = +125 OUTPUT VOLTAGE vs. OUTPUT CURRENT (mA)OUTPUT VOLTAGE (V) = = = = OUTPUT CURRENT MUST NOT EXCEED 50mA ABS MAX LIMIT.

6 INTERMITTENT PEAK CURRENTS MAY BE EFFICIENCY vs. LOAD CURRENT50 MAX662A -03 LOAD CURRENT (mA)EFFICIENCY (%)408090701030507090406080100 VCC = = = = OUTPUT CURRENT MUST NOT EXCEED 50mA ABS MAX LIMIT. INTERMITTENT PEAK CURRENTS MAY BE IOUT 30mA,VCC= to IOUT 20mA0mA IOUT 24mA,VCC= to IOUT 16mAMAX662 +12V, 30mA Flash MemoryProgramming Supply_____ 3 LOAD-TRANSIENT RESPONSEA: OUTPUT CURRENT, 20mA/div, IOUT = 0mA to 30mA B: OUTPUT VOLTAGE RIPPLE, 100mV/div, VCC = Operating Characteristics (continued)(Circuit of Figure 3a, TA= +25 C, unless otherwise noted.)LINE-TRANSIENT RESPONSEA: Supply VOLTAGE, 2V/div, VCC = to , IOUT = 30mA B: OUTPUT VOLTAGE RIPPLE, 200mV/div1ms/divAB0V0V_____Pin DescriptionNAMEFUNCTION1C1-Negative terminal for the first charge-pump capacitorPIN2C1+Positive terminal for the first charge-pump capacitor4C2+Positive terminal for the secondcharge-pump capacitor3C2-Negative terminal for the secondcharge-pump capacitor7 GNDG round6 VOUT+12V Output Voltage.

7 VOUT= VCCwhen in shutdown Voltage8 Active-high CMOS-logic levelShutdown Input. SHDN is internallypulled up to VCC. Connect to GND fornormal operation. In shutdown mode,the charge pumps are turned off andVOUT= +C2-C2+C4 FVCCVCCS1S2S1S1S1S2S2 GNDOSCILLATORVREFR1R2 SHDNVOUTC5 FC3* F+12V SWITCH CLOSURES SHOWN FOR CHARGE PUMP IN THE TRANSFER MODE * C3 NOT REQUIRED. FOR MAX662 AMPF igure 1. Block DiagramMAX662A_____Detailed DescriptionOperating PrincipleThe MAX662A provides a regulated 12V output voltageat 30mA from a 5V 5% power Supply , making it idealfor Flash EEPROM Programming applications. It usesinternal charge pumps and external capacitors to gen-erate +12V, eliminating inductors.

8 Regulation is provid-ed by a pulse-skipping scheme that monitors theoutput voltage level and turns on the charge pumpswhen the output voltage begins to 1 shows a simplified block diagram of theMAX662A. When the S1 switches are closed and theS2 switches are open, capacitors C1 and C2 arecharged up to VCC. The S1 switches are then openedand the S2 switches are closed so that capacitors C1and C2 are connected in series between VCCandVOUT. This performs a voltage tripling function. A pulse-skipping feedback scheme adjusts the output voltageto 12V 5%. The efficiency of the MAX662A with VCC=5V and IOUT= 30mA is typically 76%.

9 See theEfficiency vs. Load Current graph in the TypicalOperating one oscillator cycle, energy is transferred fromthe charge-pump capacitors to the output filter capaci-tor and the load. The number of cycles within a giventime frame increases as the load current increases oras the input Supply voltage decreases. In the limitingcase, the charge pumps operate continuously, and theoscillator frequency is nominally ModeThe MAX662A enters shutdown mode when SHDN is alogic high. SHDN is a TTL/CMOS-compatible input sig-nal that is internally pulled up to VCC. In shutdownmode, the charge-pump switching action is halted andVINis connected to VOUT through a 1k switch.

10 Whenentering shutdown, VOUT declines to VCCin typically13ms. Connect SHDN to ground for normal VCC= 5V, it takes typically 400 s for the outputto reach 12V after SHDN goes low (Figure 2)._____Applications InformationCompatibility with MAX662 The MAX662A is a 100%-compatible upgrade of theMAX662. The MAX662A does not require capacitor C3,although its presence does not affect SelectionCharge-Pump Capacitors, C1 and C2 The capacitance values of the charge-pump capacitorsC1 and C2 are critical. Use ceramic or tantalum capaci-tors in the F to F range. For applications requir-ing operation over extended and/or military temperatureranges, use F tantalum capacitors for C1 and C2(Figure 3b).