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general description the MAX1760/MAX1760h are high-efficiency, low-noise, step-up dc-dc converters intended for use in battery- powered wireless applications. they combine low quies- cent supply current (100?) with a high 1mhz operating frequency. small external components and tiny 10-pin tdfn and ?ax packages make this device an excel- lent choice for small hand-held applications. the MAX1760 is activated by a logic-low on signal while the MAX1760h is activated by a logic-high on input. both devices use a synchronous-rectified pulse-width- modulation (pwm) boost topology to generate 2.5v to 5.5v outputs from a wide range of inputs, such as 1 to 3 alkaline or nicd/nimh cells or a single lithium-ion (li+) cell. proprietary idle-mode circuitry significantly improves light-load efficiency and smoothly transitions to fixed-frequency pwm operation at higher load currents. low-noise, forced-pwm mode is available for applica- tions requiring constant-frequency operation at all load currents. pwm operation can also be synchronized to an external clock to protect sensitive frequency bands in communications equipment. analog soft-start and adjustable current limit permit optimization of efficiency, external component size, and output voltage ripple. applications digital cordless phones pcs phones wireless handsets hand-held instruments palmtop computers personal communicators two-way pagers features ? up to 94% efficiency ? 0.7v to 5.5v input range ? up to 800ma output ? fixed 3.3v output (or adjustable from 2.5v to 5.5v) ? pwm synchronous-rectified topology ? low-noise, constant-frequency operation (1mhz) ? 0.1a logic-controlled shutdown ? synchronizable switching frequency ? adjustable current limit ? adjustable soft-start ? 10-pin max package ? 10-pin 3mm x 3mm tdfn package MAX1760/MAX1760h 0.8a, low-noise, 1mhz, step-up dc-dc converter ________________________________________________________________ maxim integrated products 1 1 2 3 4 5 10 9 8 7 6 pout lx pgnd fb gnd ref iset max top view clk/sel out on (on) (on) for MAX1760h 8 9 10 lx pout on (on) 3 2 1 gnd ref iset 7 pgnd 4 fb 6 clk/sel 5 out tdfn (3mm x 3mm) MAX1760 MAX1760h MAX1760 MAX1760h pgnd fb gnd pout lx iset out ref clk/sel input = 0.7v to v out v out = 3.3v, 800ma on MAX1760 t ypical operating circuit 19-1660; rev 2; 1/04 evaluation kit available idle mode is a trademark of maxim integrated products, inc. pin configurations for pricing, delivery, and ordering information, please contact maxim/dallas direct! at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. ordering information part temp range pin-package on logic MAX1760 etb -40? to +85? 10 tdfn low MAX1760eub -40? to +85? 10 ?ax low MAX1760h etb -40? to +85? 10 tdfn high MAX1760heub -40? to +85? 10 ?ax high
MAX1760/MAX1760h 0.8a, low-noise, 1mhz, step-up dc-dc converter 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics (clk/sel = fb = pgnd = gnd, iset = ref, out = pout, v out = 3.6v, t a = 0c to +85c . typical values are at t a = +25?, unless otherwise noted.) stresses beyond those listed under ?bsolute maximum ratings?may cause permanent damage to the device. these are stress rating s only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specificatio ns is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. on, on , out, clk/sel to gnd ..............................-0.3v to +6v pgnd to gnd.....................................................................?.3v lx to pgnd ............................................-0.3v to (v pout + 0.3v) pout to out ......................................................................?.3v ref, fb, iset, pout to gnd...................-0.3v to (v out + 0.3v) continuous power dissipation (t a = +70?) 10-pin ?ax (derate 5.6mw/? above +70?) ...........444mw 10-pin tdfn (derate 24.4mv? above +70?) .........1951mw operating temperature range ...........................-40? to +85? junction temperature ......................................................+150? storage temperature range .............................-65? to +150? lead temperature (soldering, 10s) .................................+300? parameter conditions min typ max units dc-dc converter input voltage range (note 1) 0.7 5.5 v minimum startup voltage i load < 1ma, t a = +25? (note 2) 0.9 1.1 v temperature coefficient of startup voltage i load < 1ma -2.3 mv/? frequency in startup mode v out = 1.5v 125 500 1000 khz internal oscillator frequency clk/sel = out 0.8 1 1.2 mhz oscillator maximum duty cycle (note 3) 80 86 90 % external clock frequency range 0.5 1.2 mhz output voltage v fb < 0.1v, clk/sel = out, includes load regulation for 0 < i lx < 0.55a 3.17 3.3 3.38 v fb regulation voltage adjustable output, clk/sel = out, includes load regulation for 0 < i lx < 0.55a 1.215 1.240 1.270 v fb input leakage current v fb = 1.35v (t a = +25?, MAX1760etb, MAX1760hetb) 0.01 100 na load regulation clk/sel = out, no load to full load (0 < i lx < 1.0a) -1.5 % output voltage adjust range 2.5 5.5 v output voltage lockout threshold rising edge (note 4) 2.00 2.15 2.30 v iset input leakage current v iset = 1.25v (t a = +25?, MAX1760etb, MAX1760hetb) ?.01 ?0 na supply current in shutdown v on = 3.6v, v on = 0v 0.1 5 a no-load supply current clk/sel = gnd (note 5) 100 185 ? no-load supply current forced-pwm mode clk/sel = out 2.5 ma dc-dc switches pout leakage current v lx = 0, v out = 5.5v (t a = +25?, MAX1760etb, MAX1760hetb) 0.1 10 ? lx leakage current v lx = v out = 5.5v, in shutdown (t a = +25?, MAX1760etb, MAX1760hetb) 0.1 10 ?
MAX1760/MAX1760h 0.8a, low-noise, 1mhz, step-up dc-dc converter _______________________________________________________________________________________ 3 electrical characteristics (clk/sel = fb = pgnd = gnd, iset = ref, out = pout, v out = 3.6v, t a = -40c to +85c , unless otherwise noted.) (note 7) electrical characteristics (continued) (clk/sel = fb = pgnd = gnd, iset = ref, out = pout, v out = 3.6v, t a = 0c to +85c . typical values are at t a = +25?, unless otherwise noted.) parameter conditions min typ max units n-channel 0.15 0.28 switch on-resistance p-channel 0.25 0.45 ? n-channel current limit 1.0 1.25 1.6 a p-channel turn-off current clk/sel = gnd 20 60 120 ma references reference output voltage i ref = 0 1.230 1.250 1.270 v reference load regulation -1? < iref < +50? 5 15 mv reference supply rejection 2.5v < v out < 5v 0.2 5 mv logic inputs clk/sel input low level 2.5v v out 5.5v 0.2 x v out v clk/sel input high level 2.5v v out 5.5v 0.8 x v out v 1.1v v out 1.8v 0.2 on, on input low level (note 6) 1.8v v out 5.5v 0.4 v 1.1v v out 1.8v v out - 0.2 on, on input high level (note 6) 1.8v v out 5.5v 1.6 v input leakage current clk/sel, on , on (t a = +25?, MAX1760etb, MAX1760hetb) 0.01 1a minimum clk/sel pulse width 200 ns maximum clk/sel rise/fall time 100 ns parameter conditions min max units dc-dc converter output voltage v fb < 0.1v, clk/sel = out, includes load regulation for 0 < i lx < 0.55a 3.17 3.38 v fb regulation voltage adjustable output, clk/sel = out, includes load regulation for 0 < i lx < 0.55a 1.215 1.270 v internal oscillator frequency clk/sel = out 0.75 1.2 mhz oscillator maximum duty cycle (note 3) 80 90 % output voltage lockout threshold rising edge (note 4) 2.00 2.30 v supply current in shutdown v on = 3.6v 5 a no-load supply current clk/sel = gnd (note 5) 185 ? dc-dc switches n-channel 0.28 switch on-resistance p-channel 0.45 ?
MAX1760/MAX1760h 0.8a, low-noise, 1mhz, step-up dc-dc converter 4 _______________________________________________________________________________________ note 1: operating voltage?ince the regulator is bootstrapped to the output, once started, the MAX1760 operates down to 0.7v input. note 2: startup is tested with the circuit shown in figure 6. note 3: defines maximum step-up ratio. note 4: the regulator is in startup mode until this voltage is reached. do not apply full load current until the output exceeds 2.3v. note 5: supply current into the out pin. this current correlates directly to the actual battery-supply current, but is reduced in value according to the step-up ratio and efficiency. note 6: on (MAX1760) and on (MAX1760h) have a hysteresis of approximately 0.15 v out . note 7: specifications to -40? are guaranteed by design and not production tested. 100 0 0.0001 0.001 0.01 0.1 1 efficiency vs. output current v out = 3.3v 20 MAX1760 toc01 output current (a) efficiency (%) 40 70 90 60 80 10 30 50 a b c a: v in = 2.4v b: v in = 1.2v c: v in = 0.9v = auto mode = fpwm mode MAX1760-02 100 0 0.0001 0.001 0.01 0.1 1 efficiency vs. output current v out = 5v 20 output current (a) efficiency (%) 40 70 90 60 80 10 30 50 a: v in = 3.6v b: v in = 2.4v c: v in = 1.2v = auto mode = fpwm mode a b c maximum output current vs. input voltage MAX1760-03 0.1 1.0 0.5 1.5 2.0 2.5 3.0 3.5 4.0 0.3 0.2 0.5 0.4 0.8 0.7 0.6 0.9 input voltage (v) output current (a) v out = 3.3v v out = 5v electrical characteristics (continued) (clk/sel = fb = pgnd = gnd, iset = ref, out = pout, v out = 3.6v, t a = -40c to +85c , unless otherwise noted.) (note 7) t ypical operating characteristics (circuit of figure 2, v in = 2.4v, v out = 3.3v, t a = +25?, unless otherwise noted.) parameter conditions min max units n-channel current limit 1.0 1.6 a reference reference output voltage i ref = 0 1.230 1.270 v logic inputs clk/sel input low level 2.5v v out 5.5v 0.2 x v out v clk/sel input high level 2.5v v out 5.5v 0.8 x v out v 1.1v v out 1.8v 0.2 on, on input low level (note 6) 1.8v v out 5.5v 0.4 v 1.1v v out 1.8v v out + 0.2 on, on input high level (note 6) 1.8v v out 5.5v 1.6 v input leakage current clk/sel, on , on 1 a
MAX1760/MAX1760h 0.8a, low-noise, 1mhz, step-up dc-dc converter _______________________________________________________________________________________ 5 no-load battery current vs. input voltage MAX1760-04 0.0 0.5 1.5 1.0 2.0 2.5 02 1345 input voltage (v) input current (ma) v out = 3.3v v out = 5v total shutdown current (i lx + i out ) vs. input voltage MAX1760-05 0.1 02 146 1 10 input voltage (v) shutdown current (na) 35 internal oscillator frequency vs. temperature MAX1760-06 0.75 0.85 0.80 1.00 0.95 0.90 1.15 1.10 1.05 1.20 -40 10 -15 35 6 085 temperature ( c) frequency (mhz) startup voltage vs. output current MAX1760-07 0.001 0.01 0.1 1 output current (a) startup voltage (v) 3.0 0.0 0.5 1.0 1.5 2.0 2.5 circuit of figure 6 c a b b = +25 c c = -40 c a = +85 c peak inductor current vs. v iset MAX1760-08 0.0 0.4 0.2 0.8 0.6 1.2 1.0 1.4 0.1 0.5 0.7 0.3 0.9 1.1 1.3 v iset (v) peak inductor current (a) heavy-load switching waveforms MAX1760-09 c 0v a b a = lx pin, 5v/div b = inductor current, 200ma/div c = output ripple, 50mv/div ac-coupled t = 400ns/div light-load switching waveforms MAX1760-10 c t = 400ns/div a b a = lx pin, 5v/div b = inductor current, 200ma/div c = output ripple, 50mv/div, ac-coupled load-transient response MAX1760-11 t = 200ms/div a b v in = 1.1v, v out = 3.3v, i out = 0 and 0.2a a = i out , 100ma/div b = v out , 50mv/div, ac-coupled line-transient response MAX1760-12 400 s/div a b v in = 2.4v to 1.4v, i out = 70ma a = v in , 1v/div b = v out , 5ma/div, ac-coupled t ypical operating characteristics (continued) (circuit of figure 2, v in = 2.4v, v out = 3.3v, t a = +25?, unless otherwise noted.)
MAX1760/MAX1760h 0.8a, low-noise, 1mhz, step-up dc-dc converter 6 _______________________________________________________________________________________ noise spectrum MAX1760-13 10 1 0.1 16 4 0 12 8 frequency (mhz) noise (mv rms ) turn-on waveforms no soft-start components MAX1760-14 ov c a b t = 2ms/div a = on, 5v/div b = input current, 500ma/div c = v out , 2v/div soft-start waveforms r ss = 500k ? , c ss = 0.1 f MAX1760-15 0v c a b 2.00ms/div a = on, 5v/div b = input current, 100ma/div c = v out , 2v/div pin description t ypical operating characteristics (continued) (circuit of figure 2, v in = 2.4v, v out = 3.3v, t a = +25?, unless otherwise noted.) name function 1 iset n-channel current-limit control. for maximum current limit, connect to ref. to reduce current, supply a voltage between ref and gnd by means of a resistive voltage-divider. if soft-start is desired, connect a capacitor from iset to gnd. when on = high, or v ref <80% of nominal value, an on-chip 100k ? switched resistor discharges this pin to gnd. 2 ref 1.250v voltage reference bypass. connect a 0.22? ceramic bypass capacitor to gnd. up to 50? of external load current is allowed. pin 3 gnd ground. connect to pgnd with short trace. 4 fb dc-dc converter feedback input. to set fixed output voltage of +3.3v, connect fb to ground. for adjustable output of 2.5v to 5.5v, connect to a resistive divider from out to gnd. fb set point = 1.24v. 8 lx inductor connection 7 pgnd source of n-channel power mosfet switch 6 clk/sel clock input for the dc-dc converter. also serves to program operating mode of switcher as follows: clk/sel = lo: normal operation?perates at a fixed frequency, automatically switching to low-power mode if load is minimized. clk/sel = hi: forced-pwm mode?perates in low-noise, constant-frequency mode at all loads. clk/sel = clocked: forced-pwm mode with the internal oscillator synchronized to clk in 500khz to 1200khz range. 5 out ic power, supplied from the output. bypass to gnd with a 0.68? ceramic capacitor, and connect to pout with a series 4.7 ? resistor (figure 2). 9 pout power output. p-channel synchronous-rectifier source. on MAX1760 enable input. when on is low, the ic is on. connect to gnd for normal operation. 10 on MAX1760h enable input. when on is high, the ic is on. connect to out for normal operation.
MAX1760/MAX1760h 0.8a, low-noise, 1mhz, step-up dc-dc converter _______________________________________________________________________________________ 7 detailed description the MAX1760 is a highly efficient, low-noise power sup- ply for portable rf and hand-held instruments. it com- bines a boost switching regulator, n-channel power mosfet, p-channel synchronous rectifier, precision reference, and shutdown control (figure 1). the dc-dc converter boosts a 1-cell to 3-cell battery voltage input to a fixed 3.3v or adjustable voltage between 2.5v and 5.5v. an external schottky diode is required for output voltages greater than 4v. the MAX1760 guarantees startup with an input voltage as low as 1.1v and remains operational down to an input of just 0.7v. it is optimized for use in cellular phones and other applications requiring low noise and low qui- escent current for maximum battery life. it features fixed-frequency operation at medium and heavy loads, but at light loads, switches only as needed for optimum efficiency. this device is also capable of constant-fre- quency (1mhz), low-noise pwm operation at all load currents, or frequency-synchronized pwm operation when connected to an external clock. table 1 lists some typical outputs. shutdown reduces quiescent cur- rent to just 1?. figure 2 shows the standard applica- tion circuit for the MAX1760. step-up converter during dc-dc converter operation, the internal n-chan- nel mosfet switch turns on for the first part of each cycle, allowing current to ramp up in the inductor and store energy in a magnetic field. during the second part of each cycle, the mosfet turns off and inductor current flows through the synchronous rectifier to the 2.15v ic power 1.25v reference undervoltage lockout startup oscillator oscillator 1mhz controller mode pch nch en d en pout lx pgnd osc osc mode clk/sel iset fb en q ref fb iset gnd clk/sel on rdy ref gnd on (MAX1760h) out MAX1760 on (MAX1760) figure 1. functional diagram fb pgnd gnd pout lx iset out ref clk/sel v in = 2.4v v out = 3.3v, 800ma on MAX1760 3.3 h 0.68 f 4.7 ? 33 f 0.22 f 100 f figure 2. standard application circuit
MAX1760/MAX1760h 0.8a, low-noise, 1mhz, step-up dc-dc converter 8 _______________________________________________________________________________________ output filter capacitor and the load. as the energy stored in the inductor is depleted, the current ramps down and the synchronous rectifier turns off. at light loads, the device operates at fixed frequency or only as needed to maintain regulation, depending on the clk/sel setting (table 2). normal operation pulling clk/sel low selects the MAX1760? normal operating mode. in this mode, the device operates in pwm when driving medium-to-heavy loads, and auto- matically switches to pfm if the load requires less power. pfm operation allows higher efficiency than pwm under light-load conditions. forced-pwm operation when clk/sel is high, the MAX1760 operates in a low- noise pwm-only mode. during forced-pwm operation, the MAX1760 switches at a constant frequency (1mhz) and modulates the mosfet switch pulse width to con- trol the power transferred per cycle to regulate the out- put voltage. switching harmonics generated by fixed-frequency operation are consistent and easily fil- tered. see the noise spectrum plot in the typical operating characteristics. synchronized-pwm operation the MAX1760 can be synchronized in pwm mode to an external frequency of 500khz to 1.2mhz by applying an external clock signal to clk/sel. this allows interfer- ence to be minimized in wireless applications. the syn- chronous rectifier is active during synchronized-pwm operation. synchronous rectifier the MAX1760 features an internal, p-channel synchro- nous rectifier to enhance efficiency. synchronous recti- fication provides 5% improved efficiency over similar nonsynchronous boost regulators. in pwm mode, the synchronous rectifier is turned on during the second half of each switching cycle. in low-power mode, an internal comparator turns on the synchronous rectifier when the voltage at lx exceeds the boost regulator output, and turns it off when the inductor current drops below 60ma. when setting output voltages greater than 4v, an external 0.5a schottky diode must be connected in parallel with the on-chip synchronous rectifier. low-voltage startup oscillator the MAX1760 uses a cmos, low-voltage startup oscil- lator for a 1.1v guaranteed minimum startup input volt- age. at startup, the low-voltage oscillator switches the n-channel mosfet until the output voltage reaches 2.15v. above this level, the normal boost-converter feedback and control circuitry take over. once the device is in regulation, it can operate down to 0.7v input since internal power for the ic is bootstrapped from the output through out. do not apply full load until the output exceeds 2.3v. shutdown the MAX1760 has a shutdown mode that reduces qui- escent current to 0.1?. during shutdown ( on = high on MAX1760, on = low on MAX1760h), the reference and all feedback and control circuitry are off. during shutdown, the output voltage is one diode drop below the input voltage. table 1. typical available output current 5.0 3.6 3 750 3.3 2.4 2 3.3 1.2 1 output voltage (v) input voltage (v) number of nicd/nimh cells 800 350 output current (ma) 5.0 2.4 500 table 2. selecting the operating mode clk/sel mode features 0 normal operation high efficiency at all loads. fixed frequency at all but light loads. 1 forced pwm low noise, fixed frequency at all loads. external clock 500khz to 1.2mhz synchronized pwm low noise, fixed frequency at all loads.
reference the MAX1760 has an internal 1.250v ?% reference. connect a 0.22? ceramic bypass capacitor from ref to gnd within 0.2in (5mm) of the ref pin. ref can source up to 50? of external load current. design procedure setting the output voltages for a fixed 3.3v output, connect fb to gnd. to set other output voltages between 2.5v and 5.5v, connect a resistor voltage-divider to fb from out to gnd (figure 3). the input bias current into fb is <20na, allowing large-value divider resistors without sacrificing accuracy. connect the resistor voltage-divider as close to the ic as possible, within 0.2in (5mm) of fb. choose r2 of 270k ? or less, then calculate r1 using: where v fb , the boost-regulator feedback set point, is 1.24v. setting the switch current limit and soft-start the iset pin adjusts the inductor current limit and implements soft-start. with iset connected to ref, the inductor current limits at 1.25a. with iset connected to a resistive divider set from ref to gnd, the current limit is reduced according to: implement soft-start by placing a resistor from iset to ref and a capacitor from iset to gnd. in shutdown, iset is discharged to gnd through an on-chip 100k ? resistor. at power-up, iset is 0v and the lx current is zero. as the capacitor voltage rises, the current increases and the output voltage rises. the soft-start i 1.25a v 1.25v lim iset = ? ? ? ? ? ? r1 r2 v v 1 out fb = ? ? ? ? ? ? ? MAX1760 0.8a, low-noise, 1mhz, step-up dc-dc converter _______________________________________________________________________________________ 9 figure 3. connecting resistors for external feedback iset ref MAX1760 r ss c ss 0.22 f t ss = r ss c ss r ss 470k ? i lim = 1.25a figure 4. soft-start with maximum switch limit current iset ref MAX1760 r ss1 c ss 0.22 f r ss2 t ss = ( r ss1 ii r ss2 ) c ss i lim = 1.25a r ss1 + r ss2 r ss2 ( ) r ss1 470k ? figure 5. soft-start with reduced switch current limit fb pgnd gnd pout lx iset out ref clk/sel v in = 2.4v v out on MAX1760 100 f 3.3 h 0.68 f 4.7 ? 33 f 0.22 f r1 r2 - 1 r1 = r2 ( ) v out v fb v fb = 1.24v
time constant is: where r ss 470k ? . placing a capacitor across the lower resistor of the cur- rent-limiting resistive divider provides both current-limit and soft-start features simultaneously (figures 4 and 5). inductor selection the MAX1760? high switching frequency allows the use of a small 3.3? surface-mount inductor. the cho- sen inductor should generally have a saturation current rating exceeding the n-channel switch current limit; however, it is acceptable to bias the inductor current into saturation by as much as 20% if a slight reduction in efficiency is acceptable. lower current-rated induc- tors may be used if iset is employed to reduce the peak inductor current (see the setting the switch current limit and soft-start section). for high efficien- cy, choose an inductor with a high-frequency ferrite core material to reduce core losses. to minimize radiat- ed noise, use a toroid or shielded inductor. see table 3 for suggested components and table 4 for a list of component suppliers. connect the inductor from the battery to the lx pin as close to the ic as possible. external diode for output voltages greater than 4v, an external schottky diode must be connected from lx to pout, in parallel with the on-chip synchronous rectifier (figure 6). the diode should be rated for 0.5a. representative devices are motorola mbr0520l, nihon ep05q03l, or generic 1n5817. this external diode is also recom- mended for applications that must start with input volt- ages at or below 1.8v. the schottky diode carries current during startup and after the synchronous rectifi- er turns off; thus, its current rating only needs to be 500ma. connect the diode as close to the ic as possi- ble. do not use ordinary rectifier diodes; their slow switching speeds and long reverse-recovery times ren- der them unacceptable. for circuits that do not require startup with inputs below 1.8v and have an output of 4v or less, no external diode is needed. input and output filter capacitors choose input and output filter capacitors that will ser- vice the input and output peak currents with accept- able voltage ripple. choose input capacitors with working voltage ratings over the maximum input volt- trc ss ss ss = MAX1760/MAX1760h 0.8a, low-noise, 1mhz, step-up dc-dc converter 10 ______________________________________________________________________________________ table 3. component selection guide sanyo poscap series sumida cdrh5d18 kemet t510 series toko type d518lc sumida cdrh4d28 surface mount avx tps series toko type d52lc capacitors inductors production method motorola mbr0520l eic sb series diodes table 4. component suppliers note: please indicate that you are using the MAX1760 when contacting these component suppliers. fb pgnd gnd pout mrb0520l lx iset out ref clk/sel v in = 0.7v to vout v out on MAX1760 100 f 3.3 h 0.68 f 4.7 ? 33 f 0.22 f figure 6. connection with external schottky diode for output voltages greater than 4v, or to assist low-voltage startup supplier phone avx usa: 843-448-9411 eic usa: 916-941-0712 kemet usa: 810-287-2536 motorola usa: 408-629-4789 japan: 81-45-474-7030 sumida usa: 847-956-0666 japan: 011-81-3-3667-3302 toko usa: 847-297-0070
age, and output capacitors with working voltage ratings higher than the output. the input filter capacitor reduces peak currents drawn from the input source and also reduces input switching noise. the input voltage source impedance determines the required value of the input capacitor. when operat- ing directly from one or two nimh cells placed close to the MAX1760, use a single 33? low-esr input filter capacitor. with higher impedance batteries, such as alkaline and li+, a higher value input capacitor may improve efficiency. the output filter capacitor reduces output ripple voltage and provides the load with transient peak currents when necessary. for the output, a 100?, low-equiva- lent-series-resistance (esr) capacitor is recommended for most applications. sanyo poscap, panasonic sp/cb, and kemet t510 are good low-esr capacitors. low-esr tantalum capacitors offer a good tradeoff between price and performance. do not exceed the ripple current ratings of tantalum capacitors. avoid aluminum electrolytic capacitors; their high esr typically results in higher output ripple voltage. other external components two ceramic bypass capacitors are required for proper operation. bypass ref to gnd with 0.22?. also, bypass out to gnd with a 0.68? ceramic capacitor, and connect out to pout with a 4.7 ? resistor. each of these components should be placed as close to its respective ic pins as possible, within 0.2in (5mm). table 4 lists suggested suppliers. layout considerations high switching frequencies and large peak currents make pc board layout a critical part of design. poor design causes excessive emi and ground bounce, both of which can cause instability or regulation errors by corrupting the voltage and current feedback signals. power components?uch as the inductor, converter ic, filter capacitors, and output diode?hould be placed as close together as possible, and their traces should be kept short, direct, and wide. keep the voltage feed- back network very close to the ic, within 0.2in (5mm) of the fb pin. keep noisy traces, such as those from the lx pin, away from the voltage feedback network and guarded from them using grounded copper. refer to the MAX1760 evaluation kit for a full pc board example. MAX1760/MAX1760h 0.8a, low-noise, 1mhz, step-up dc-dc converter ______________________________________________________________________________________ 11 transistor count: 1361 chip information
MAX1760/MAX1760h 0.8a, low-noise, 1mhz, step-up dc-dc converter 10lumax.eps package outline, 10l umax/usop 1 1 21-0061 i rev. document control no. approval proprietary information title: top view front view 1 0.498 ref 0.0196 ref s 6 side view bottom view 0 0 6 0.037 ref 0.0078 max 0.006 0.043 0.118 0.120 0.199 0.0275 0.118 0.0106 0.120 0.0197 bsc inches 1 10 l1 0.0035 0.007 e c b 0.187 0.0157 0.114 h l e2 dim 0.116 0.114 0.116 0.002 d2 e1 a1 d1 min - a 0.940 ref 0.500 bsc 0.090 0.177 4.75 2.89 0.40 0.200 0.270 5.05 0.70 3.00 millimeters 0.05 2.89 2.95 2.95 - min 3.00 3.05 0.15 3.05 max 1.10 10 0.60.1 0.60.1 ? 0.500.1 h 4x s e d2 d1 b a2 a e2 e1 l l1 c gage plane a2 0.030 0.037 0.75 0.95 a1 package information (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline info rmation, go to www.maxim-ic.com/packages .) 12 ______________________________________________________________________________________
MAX1760/MAX1760h 0.8a, low-noise, 1mhz, step-up dc-dc converter ______________________________________________________________________________________ 13 pa ck ag e information (continued) (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline info rmation, go to www.maxim-ic.com/packages .) 6, 8, &10l, dfn thin.eps proprietary information title: approval document control no. rev. 2 1 package outline, 6, 8 & 10l, tdfn, exposed pad, 3x3x0.80 mm 21-0137 d l c l c semiconductor dallas a2 a pin 1 index area d e a1 d2 b e2 [(n/2)-1] x e ref. e k 1 n 1 l e l a l pin 1 id c0.35 detail a e number of leads shown are for reference only ______________________________________________________________________________________ 13
MAX1760/MAX1760h 0.8a, low-noise, 1mhz, step-up dc-dc converter maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circu it patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. 14 ____________________maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 2004 maxim integrated products printed usa is a registered trademark of maxim integrated products. pa ck ag e information (continued) (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline info rmation, go to www.maxim-ic.com/packages .) document control no. approval title: proprietary information rev. 2 2 common dimensions symbol min. max. a 0.70 0.80 d 2.90 3.10 e 2.90 3.10 a1 0.00 0.05 l 0.20 0.40 pkg. code 6 n t633-1 1.500.10 d2 2.300.10 e2 0.95 bsc e mo229 / weea jedec spec 0.400.05 b 1.90 ref [(n/2)-1] x e 1.500.10 mo229 / weec 1.95 ref 0.300.05 0.65 bsc 2.300.10 t833-1 8 package variations 21-0137 0.250.05 2.00 ref mo229 / weed-3 0.50 bsc 1.500.10 2.300.10 10 t1033-1 0.25 min. k a2 0.20 ref. d semiconductor dallas package outline, 6, 8 & 10l, tdfn, exposed pad, 3x3x0.80 mm

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