_______________general description the MAX662A is a regulated +12v, 30ma-output, charge- pump dc-dc converter. it provides the necessary +12v ?% output to program byte-wide flash memories, and requires no inductors to deliver a guaranteed 30ma out- put from inputs as low as 4.75v. it fits into less than 0.1in 2 of board space. the MAX662A is a pin-compatible upgrade to the max662, and is recommended for new designs. the MAX662A offers lower quiescent and shut- down currents, and guarantees the output current over all temperature ranges. the MAX662A is the first charge-pump boost converter to provide a regulated +12v output. it requires only a few inexpensive capacitors, and the entire circuit is complete- ly surface-mountable. a logic-controlled shutdown pin that interfaces directly with microprocessors reduces the supply current to only 0.5?. the MAX662A comes in 8-pin narrow so and dip packages. for higher-current flash memory programming solutions, refer to the data sheets for the max734 (120ma output current, guaranteed) and max732 (200ma output cur- rent, guaranteed) pwm, switch-mode dc-dc converters. or, refer to the max761 data sheet for a 150ma, pfm switch-mode dc-dc converter that operates from inputs as low as 2v. ________________________applications +12v flash memory programming supplies compact +12v op-amp supplies switching mosfets in low-voltage systems dual-output +12v and +20v supplies ____________________________features ? regulated +12v ?% output voltage ? 4.5v to 5.5v supply voltage range ? fits in 0.1in 2 ? guaranteed 30ma output ? no inductor?ses only 4 capacitors ? 185? quiescent current ? logic-controlled 0.5? shutdown ? 8-pin narrow so and dip packages ______________ordering information MAX662A +12v, 30ma flash memory programming supply ________________________________________________________________ maxim integrated products 1 1 2 3 4 8 7 6 5 shdn gnd v out v cc c2+ c2- c1+ c1- MAX662A dip/so top view __________________pin configuration MAX662A flash
memory 4.7 m f 4.7 m f 0.22 m f 0.22 m f output
12v ?%
30ma v cc shdn c1+ c1- v out c2- c2+ gnd input
4.75v to 5.5v v pp __________typical operating circuit call toll free 1-800-998-8800 for free samples or literature. 19-0253; rev 1; 8/94 evaluation kit manual follows data sheet part MAX662Acpa MAX662Acsa MAX662Ac/d 0? to +70? 0? to +70? 0? to +70? temp. range pin-package 8 plastic dip 8 so dice* MAX662Aepa -40? to +85? 8 plastic dip MAX662Aesa -40? to +85? 8 so MAX662Amja -55? to +125? 8 cerdip** * dice are tested at t a = +25?. ** contact factory for availability and processing to mil-std-883.
MAX662A +12v, 30ma flash memory programming supply 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics (circuit of figure 3a, v cc = 4.5v to 5.5v, t a = t min to t max , unless otherwise noted.) stresses beyond those listed under ?bsolute 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. v cc to gnd ................................................................-0.3v to 6v shdn..........................................................-0.3v to (v cc + 0.3v) i out continuous..................................................................50ma continuous power dissipation (t a = +70?) plastic dip (derate 9.09mw/? above +70?) ............727mw so (derate 5.88mw/? above +70?) .........................471mw cerdip (derate 8.00mw/? above +70?) .................640mw operating temperature ranges MAX662Ac_a .....................................................0? to +70? MAX662Ae_a ..................................................-40? to +85? MAX662Amja................................................-55? to +125? storage temperature range .............................-65? to +160? lead temperature (soldering, 10sec) .............................+300? MAX662Ac/e v cc = v shdn = 5v, i out = 30ma v cc = 5v, i out = 30ma MAX662Am no load, v shdn = 0v no load, v shdn = v cc v cc = v shdn = 5v v cc = 5v, i out = 30ma v cc = 5v, v shdn = 0v conditions ? 0 shdn pin current -50 -15 -5 11.4 12 12.6 11.4 12 12.6 11.4 12 12.6 v 0.4 v il shutdown input threshold 2.4 v ih k 12 r sw v cc -to-v out switch impedance % 76 power efficiency v 11.4 12 12.6 v out output voltage ? 185 500 i cc supply current ? 0.5 10 shutdown current khz 500 f osc oscillator frequency units min typ max symbol parameter __________________________________________typical operating characteristics (circuit of figure 3a, t a = +25?, unless otherwise noted.) 100 4.50 5.25
supply current vs. supply voltage 140 300 MAX662A-01 supply voltage (v) supply current ( m a) 220 180 4.75 260 5.00
120 160 200 240 280 5.50 t a = -55? t a = 0? t a = +25? t a = +125? 12.6 10.6 0 20 60 100
output voltage vs. output current 11.0 12.2 MAX662A-02 output current (ma) output voltage (v) 40 80 11.8 11.4 10 30 50 70 90 10.8 11.2 11.6 12.0 12.4 v cc = 5.5v v cc = 5.0v v cc = 4.75v v cc = 4.5v continuous output current must
not exceed 50ma abs max limit.
intermittent peak currents may
be higher. 30 0 20 60 100
efficiency vs. load current 50 MAX662A-03 load current (ma) efficiency (%) 40 80 90 70 10 30 50 70 90 40 60 80 100 v cc = 5.5v v cc = 5.0v v cc = 4.75v v cc = 4.5v continuous output current
must not exceed 50ma abs max
limit. intermittent peak
currents may be higher. 0ma i out 30ma, v cc = 4.75v to 5.5v 0ma i out 20ma 0ma i out 24ma, v cc = 4.75v to 5.5v 0ma i out 16ma MAX662Ac/e MAX662Am 1 2.5
MAX662A +12v, 30ma flash memory programming supply _______________________________________________________________________________________ 3 load-transient response a: output current, 20ma/div, i out = 0ma to 30ma
b: output voltage ripple, 100mv/div, v cc = 5.0v 1ms/div a b 0ma _____________________________typical operating characteristics (continued) (circuit of figure 3a, t a = +25?, unless otherwise noted.) line-transient response a: supply voltage, 2v/div, v cc = 4.5v to 5.5v, i out = 30ma
b: output voltage ripple, 200mv/div 1ms/div a b 0v 0v _____________________pin description name function 1 c1- negative terminal for the first charge- pump capacitor pin 2 c1+ positive terminal for the first charge- pump capacitor 4 c2+ positive terminal for the second charge-pump capacitor 3 c2- negative terminal for the second charge-pump capacitor 7 gnd ground 6 v out +12v output voltage. v out = v cc when in shutdown mode. 5 v cc supply voltage 8 active-high cmos-logic level shutdown input. shdn is internally pulled up to v cc . connect to gnd for normal operation. in shutdown mode, the charge pumps are turned off and v out = v cc . shdn MAX662A c1- c1+ c2- c2+ c4
4.7 m f 0.22 m f 0.22 m f v cc v cc s1 s2 s1 s1 s1 s2 s2 gnd oscillator vref r1 r2 shdn v out c5
4.7 m f c3*
0.1 m f +12v switch closures shown for charge pump in the transfer mode
* c3 not required. for max662 only. error
amp figure 1. block diagram
MAX662A _______________detailed description operating principle the MAX662A provides a regulated 12v output voltage at 30ma from a 5v ?% power supply, making it ideal for flash eeprom programming applications. it uses internal charge pumps and external capacitors to gen- erate +12v, eliminating inductors. regulation is provid- ed by a pulse-skipping scheme that monitors the output voltage level and turns on the charge pumps when the output voltage begins to droop. figure 1 shows a simplified block diagram of the MAX662A. when the s1 switches are closed and the s2 switches are open, capacitors c1 and c2 are charged up to v cc . the s1 switches are then opened and the s2 switches are closed so that capacitors c1 and c2 are connected in series between v cc and v out . this performs a voltage tripling function. a pulse- skipping feedback scheme adjusts the output voltage to 12v ?%. the efficiency of the MAX662A with v cc = 5v and i out = 30ma is typically 76%. see the efficiency vs. load current graph in the typical operating characteristics . during one oscillator cycle, energy is transferred from the charge-pump capacitors to the output filter capaci- tor and the load. the number of cycles within a given time frame increases as the load current increases or as the input supply voltage decreases. in the limiting case, the charge pumps operate continuously, and the oscillator frequency is nominally 500khz. shutdown mode the MAX662A enters shutdown mode when shdn is a logic high. shdn is a ttl/cmos-compatible input sig- nal that is internally pulled up to v cc . in shutdown mode, the charge-pump switching action is halted and v in is connected to v out through a 1k switch. when entering shutdown, v out declines to v cc in typically 13ms. connect shdn to ground for normal operation. when v cc = 5v, it takes typically 400? for the output to reach 12v after shdn goes low (figure 2). __________applications information compatibility with max662 the MAX662A is a 100%-compatible upgrade of the max662. the MAX662A does not require capacitor c3, although its presence does not affect performance. capacitor selection charge-pump capacitors, c1 and c2 the capacitance values of the charge-pump capacitors c1 and c2 are critical. use ceramic or tantalum capaci- tors in the 0.22? to 1.0? range. for applications requir- ing operation over extended and/or military temperature ranges, use 1.0? tantalum capacitors for c1 and c2 (figure 3b). input and output capacitors, c4 and c5 the type of input bypass capacitor (c4) and output filter capacitor (c5) affects performance. tantalums, ceramics or aluminum electrolytics are suggested. for smallest size, use sprague 595d475x9016a7 surface-mount capacitors, which are 3.51mm x 1.81mm. for lowest ripple, use low- esr through-hole ceramic or tantalum capacitors. for low- est cost, use aluminum electrolytic or tantalum capacitors. figure 3a shows the component values for proper opera- tion over the commercial temperature range using mini- mum board space. the input bypass capacitor (c4) and output filter capacitor (c5) should both be at least 4.7? when using sprague? miniature 595d series of tantalum chip capacitors. figure 3b shows the suggested compo- nent values for applications over extended and/or mili- tary temperature ranges. the values of c4 and c5 can be reduced to 2? and 1?, respectively, when using ceramic capacitors. if using aluminum electrolytics, choose capacitance values of 10? or larger for c4 and c5. note that as v cc increases above 5v and the output current decreases, the amount of ripple at v out increases due to the slower oscillator frequency combined with the higher input volt- age. increase the input and output bypass capacitance to reduce output ripple. table 1 lists various capacitor suppliers. +12v, 30ma flash memory programming supply 4 _______________________________________________________________________________________ figure 2. MAX662A exiting shutdown circuit of figure 3, v cc = 5v, i out = 200? 5v 0v 12v 5v shdn v out 200?/div
layout considerations layout is critical, due to the MAX662A? high oscillator frequency. good layout ensures stability and helps maintain the output voltage under heavy loads. for best performance, use very short connections to the capaci- tors. the order of importance is: c4, c5, c1, c2. flash eeprom applications the circuit of figure 3a is a +12v ?% 30ma flash eeprom programming power supply. a microproces- sor controls the programming voltage via the shdn pin. when shdn is low, the output voltage (which is connected to the flash memory v pp supply-voltage pin) rises to +12v to facilitate programming the flash memo- ry. when shdn is high, the output voltage is connected to v in through an internal 1k resistor. paralleling devices two MAX662As can be placed in parallel to increase output drive capability. the v cc , v out , and gnd pins can be paralleled, reducing pin count. use a single bypass capacitor and a single output filter capacitor with twice the capacitance value if the two devices can be placed close to each other. if the MAX662As cannot be placed close together, use separate bypass and output capacitors. the amount of output ripple observed will determine whether single input bypass and output filter capacitors can be used. under certain conditions, one device may supply the total output cur- rent. therefore, regardless of the number of devices in parallel, the maximum continuous current must not exceed 50ma. 12v and 20v dual-output power supply using the charge-pump voltage-doubler circuit of figure 4, the MAX662A can produce a +20v supply from a single +5v supply. figure 5 shows the current capability of the +20v supply. MAX662A +12v, 30ma flash memory programming supply _______________________________________________________________________________________ 5 table 1. capacitor suppliers MAX662A *c1
1.0 m f
2 1 8 7 c2- c2+ v cc v out programming
control
direct from
m p *c2
1.0 m f v in
4.75v to 5.5v *c4
22 m f v out
+12v ?%
at 30ma *c5
22 m f c1+ c1- shdn gnd 3 4 5 6 *sprague 595d series or equivalent MAX662A c1
0.22 m f
2 1 8 7 c2- c2+ v cc v out programming
control
direct from
m p c2
0.22 m f v in
4.75v to 5.5v c4
4.7 m f v out
+12v ?%
at 30ma c5
4.7 m f c1+ c1- shdn gnd 3 4 5 6 figure 3a. flash eeprom programming power supply for commercial temperature range applications figure 3b. flash eeprom programming power supply for extended and/or military temperature range applications supplier phone number fax number capacitor capacitor type* grm42-6z5u224m50 0.22? ceramic (sm) murata erie (814) 237-1431 (814) 238-0490 rpe123z5u105m50v 1.0? ceramic (th) 595d475x9016a7 4.7? tantalum (sm) sprague electric (603) 224-1961 (207) 324-4140 (603) 224-1430 (207) 324-7223 595d105x9016a7 1.0? tantalum (sm) *note: (sm) denotes surface-mount component, (th) denotes through-hole component.
MAX662A +12v, 30ma flash memory programming supply 6 _______________________________________________________________________________________ MAX662A 0.22 m f
2 1 8 5 c2- c2+ v out 0.22 m f v in =
5v ?% 1 m f 1 m f 20v
output 1 m f c1+ c1- shdn v cc 3 4 6 12v
output gnd 1n5818 1n5818 2 m f 7 figure 4. +12v and +20v dual supply from a +5v input 20.0 16.0 030
19.2 MAX662Afig 5 20v output current (ma) 20v output voltage (v) 15 17.6 16.8 510 25 18.4 20 35 40 circuit of figure 4
v cc = 4.75v
t a = +25? with +12v output
unloaded with 34ma load
on +12v output figure 5. +20v supply output current capability ___________________chip topography c1- shdn v cc c2+ c2- c1+ gnd v out 0.086"
(2.184mm) 0.086"
(2.184mm) transistor count: 225 substrate connected to v out
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