19-4749; Rev 3; 5/93 _ Toke mele E ran IT epee General Description The MAX736/MAX737/MAX739/MAX759 are CMOS, in- verting, switch-mode regulators with an internal power MOSFET. Guaranteed output power for the MAX739 is 1,.25W when powered from a +4.5V input, and 1.5W when powered from +6V. Quiescent supply current for the MAX739 is typically 1.7mA, and a shutdown mode reduces this to 1A. These power-conserving features, along with high efficiency and an application circuit that lends itself to miniaturization, make these parts excel in a broad range of on-card and portable equipment applications. The MAX736/MAX737/MAX739 have fixed outputs of -12V, -15V, and -5V respectively. The MAX759 is adjustable from OV to -15V. Output voitages beyond -15V require a transformer. These inverting DC-DC converters employ a high-perfor- mance, current-mode, pulse-width modulation (PWM) con- PART TEMP. RANGE PIN-PACKAGE trol scheme to provide tight output voltage regulation and MAX736CPD 0C to +70C 14 Plastic DIP low noise. The fixed-frequency oscillator is factory-trimmed MAX736CWE OC to +70C 16 Wide SO to 165kHz, allowing easy noise filtering. The devices are production tested in an actual application circuit, and MAX736C/D oe to +70C Dice output accuracy is guaranteed at +5% over all specified MAX736EPD ~40C to +85C 14 Plastic DIP conditions of line, toad, and temperature. MAX736EWE -40C to +85C 16 Wide SO The input voltage range is +4V to +15V. For similar devices MAX736MJD -58C to +125C 14 CERDIP** with smaller packages and an input voltage range of +4V MAX737CPD 0C to +70C 14 Plastic DIP to +11V, refer to the MAX735/MAX755 data sheet. MAX737CWE OClo+70C 16 Wide SO Applications MAX737C/0 0C to +70C Dice* Low-Noise Analog Signal Processing Circuits MAX737EPD -40C to +85C 14 Plastic DiP LCD Bias Supplies MAX737EWE -40C to +85C 16 Wide SO Power Supplies for ECL MAX737MJSD -55C to +125C 14 CERDIP* Board-Level DC-DC Conversion Battery-Powered Equipment Computer Peripherals Typical Operating Circuit MAALM 5V, -12V, -15V, and Adjustable Inverting Current-Mode PWM Regulators Features Pre-Set -5V, -12V, -15V or Adjustable Outputs @ Convert Positive Voltages to Negative 1.25W Guaranteed Output Power @ 83% Typical Efficiency @ 1.7mA Quiescent Current (MAX739) @ 1A Shutdown Mode (MAX739) @ +4V to +15V Input Voltage Range @ 165kHz Current-Mode PWM Low Noise and Jitter @ Undervoltage Lockout and Soft-Start Protection Ordering Information Ordering Information continued on last page of data sheet. * Contact factory for dice specifications. **Contact factory for availability and processing to MIL-STD-883. Pin Configurations 6SZLXVW/6EZLXVW/LEZLXVW/9ELXVN VIN 45VIO11V TOP VIEW i. J" PhS V+ {a 4] V+ + Vv. - aaa SHON Vout rt SHON [2 Ose 3] a ee il DRV- vReF [3] = MAX737_sft2] LX 3.3pF MAX739 aur | anaxua Ne. [4] ax7sg Jt] & =' MAX739 1NS817 Vout sg (| GND ss X oH -V 5 19} 200mA neo. [a] Fa] oRV- oT Tze ono 10uH T 33uF cc (7 ra | Vour LL = = = = DIP SURFACE-MOUNT APPLICATION Pin Configurations continued on last page. MAXIMA Call toll free 1-800-998-8800 for free samples or literature. Maxim Integrated Products 3-177MAX736/MAX737/MAX739/MAX759 =5V, -12V, -15V, and Adjustable inverting Current-Mode PWM Regulators ABSOLUTE MAXIMUM RATINGS Supply Voltage (V+ to GND) (Note 1) MAX739/MAX759 1... cece 15.5V, -0.3V MAX736 .0 0 cc eee 9.5V, -0.3V MAX737 2... 6.5V, -0.3V Maximum Input/Output Differential MAX736/MAX737 . 0... 2c ccc e ene n ee eee 22V MAX739/MAX759 (Non-Bootstrapped) ............. 22V MAX739/MAX759 (Bootstrapped) ..............065 17V Negative Drive Voltage (DRV- to V+) ............ -17V, +0.3V Switch Voltage (LX to V+) ............ 0.0 eee -22.5V, +0.3V Feedback Voltage (VOUT to GND) ............2...... +50V Auxiliary Input Voltages (SS, CC, SHDN toGND) ............. -0.3V to (V+ + 0.3V) Peak Switch Current (ILX) 00 cece 2.5A Reference Current (IVREF) 0.6.0.0 cece cece ees 2.5mA Continuous Power Dissipation (Ta = +70C) 14-Pin Plastic DIP (derate 10.00mW/C above +70C) .. 800mW 16-Pin Wide SO (derate 9.52mW/"C above +70C) ... 762mW 14-Pin CERDIP (derate 9.09mW/"C above +70C) ... 727mW Operating Temperature Ranges: MAX73_ /MAX759C__................000. OC to +70C MAX73_/MAX759E__ .... 2. -40C to +85C MAX73_ /MAX759MJUD .............000.. -55C to +125C Junction Temperatures: MAX73_ /MAX759E/C_ ow. ee +150C MAX73_ /MAX759MUD .. 0.0 eee +175C Storage Temperature Range .............. 65C to + 160C Lead Temperature (soldering, 10sec) .............. +300C Note 1: Output voltages beyond -5V or bootstrapped operation reduce the allowable supply voltage. See Maximum Input/Output Differential specifications. 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 Bootstrapped Mode (Circuit of Figure 1, V+ = 5V, LOAD = OmA, DRV- = Vout (-5V) (MAX739/MAX759), TA = TMIN to TMAX, unless otherwise noted.) PARAMETER CONDITIONS MIN TYP MAX UNITS DRV- 2 -7V MAX736 40 8.6 Input Voltage Range DRV- 2 -10V MAX737 40 .5 Vv DRV- > -5.25V MAX739/MAX759 ce) 11.0 V+ = 4.5V to B.6Y, 41.40 412.60 I = OmA to 100mA ie oN to B.6V, = MAX796 11.40 12.60 Output Voltage ILOAD = OmA to 125mA , . V pap Oras 10m | MAX737 -14.25 -15.75 V+ = 4.5V to 11V, MAX739 -4.750 -.250 ILoAD = OMA to 250mMA | MAX759 (Notes 2,3) | -4.775 5.225 V+ = 4.5V to 8.6V 100 140 MAX736 V+ = 6V to 8.6V 125 150 V+ = 4.5V to 5.5V MAX737 100 110 Output Current u = SOO enc 250 300 mA Verde | thei) | 200280 V+ =6Vto11V 300 500 MAX736 4.2 6.0 : MAX737 6.1 9.5 Supply Current mA MAX739 1.7 3.5 MAX759 2.2 4.0 3-178 MAXILAN-5V, -12V, -15V, and Adjustable Inverting Current-Mode PWM Regulators ELECTRICAL CHARACTERISTICS (continued) Bootstrapped Mode (Circuit of Figure 1, V+ = 5V, LOAD = OmA, DRV- = Vout (-5V) (MAX739/MAX759), Ta = TMIN to TMAX, unless otherwise noted.) PARAMETER CONDITIONS MIN TYP MAX UNITS Standby Current VSHDN = OV (Note 4) 1.0 100.0 pA SHDN Logic High Voltage V+-0.5 Vv SHDN Logic Low Voltage 0.25 V SHDN Input Current 0.1 1.0 pA LX Leakage Current 10 pA Undervoltage Lockout Measured at V+ 3.7 40 Vv Reference Voltage (Note 3) 1.16 1.23 1.30 Vv Reference Drift 50 pem/c Compensation-Pin Impedance 6 kQ . MAX736/MAX739 145 185 220 Oscillator Frequency kHz MAX737/MAX759 145 185 220 ELECTRICAL CHARACTERISTICS Non-Bootstrapped Mode (Circuit of Figure 1, Ta = TMIN to TMax, unless otherwise noted.) PARAMETER CONDITIONS MIN TYP MAX UNITS MAX736 40 8.6 Input Voltage Range MAX737 40 5.5 Vv MAX739/MAX759 40 15.0 V+ = 4V to 8.6V MAX736 -11.40 -12.60 Output Voltage, No Load V+ = 4V to 5.5V MAX737 -14.25 -15.75 V (Note 2) MAX739 -4.750 -5.250 V+ = 4V to 15V MAX759 (Note 2) -4.775 -.225 MAX736 70 Output Current (Note 5) V+ = 5V MAX737 50 mA MAX739/MAX759 250 MAX736/MAX739 1.6 3.0 Supply Current, No Load V+ = 5V MAX737 2.5 4.5 mA MAX759 2.1 4.0 6SZXVW/GELXUW/LELXVW/9EZLXUN Note 2: MAX759 output voltage tests are performed using an external resistor divider to set the output voltage to -5V (see Figure 5, R39 = 15kQ, R4 = 3.69kQ2). Output voltage tolerance is +4.5% plus external feedback resistor tolerances for the MAX759. The standby supply-current specification is set at 100A due to test method limitations rather than actual device performance. The two-sigma distribution of standby supply current is less than 10,A (over temperature). 10pH inductor used with the MAX736/MAX737. 18yH inductor used with the MAX739/MAX759. Note 3: Note 4: Note 5: MAXIMA 3-179MAX736/MAX737/MAX739/MAX759 -5V, -12V, -15V, and Adjustable Inverting Current-Mode PWM Regulators 20 05 STANDBY SUPPLY CURRENT (1A) 190 180 170 150 OSCILLATOR FREQUENCY (kHz) 140 130 STANDBY SUPPLY CURRENT vs. SUPPLY VOLTAGE 125C A ! l l CIRCUIT OF FIG. 1 SHDN = 0V INTO V+ To AN 425C 4 ) 0 2 4 6 8 10 12 14 16 SUPPLY VOLTAGE (V) MAX739 OSCILLATOR FREQUENCY vs. TEMPERATURE AND SUPPLY VOLTAGE -55) Oo +25 +125C KF WA 6 2 4 6 8 10 12 14 16 SUPPLY VOLTAGE (V) SWITCHING WAVEFORMS - DISCONTINUOUS CONDUCTION A= Switch Voltage (LX) 5V/div (4.8V to -5.3V) B = Inductor Current, SO0mA/div C = Output Voltage Ripple, 50mV/div TIME = Qus/div CIRCUIT OF FIG. 1 VIN = +5V Ta=+25C LOAD CURRENT (mA) SWITCH-CURRENT LIMIT (A) MAX739 CONTINUOUS-CONDUCTION REGION 500 Ta= Vout = -5V Typical Operating Characteristics MAX739 DISCONTINUOUS-CONDUCTION REGION Tas 425C 300- Vout =-5V ago} (X= 33h) (LX = 10H) REGION 2 250 300 = 200 Fa a 200 8 10 3 = 100 100 CONDUCTION REGION 50 0 0 0 2 4 6 8 0 12 4 16 0 2 4 6 8 0 12 14 16 SUPPLY VOLTAGE (V) SUPPLY VOLTAGE (V) MAX739 SWITCH-CURRENT LIMIT vs. SOFT-START VOLTAGE SOFT-START DELAY TIME 24 T 60 T T Ta=+25C ILoap = 100mA 20 50 |_ CIRCUIT OF FIG. 1 " o Ta= 425C - 2 ra 16 A = 40 i ~~ 2 1 12 Z = 30 i a V 5 / 08 > 20 s / 04 4 10 0 0 0 100 200 300 400 500 600 0 2 4 6 8 100 120 SOFT-START (V) SOFT-START CAPACITANCE (nF) SWITCHING WAVEFORMS - CONTINUGUS CONDUCTION A= Switch Voltage (LX) 5V/div (4.8V to -5.3V) B= Inductor Current, 500mA/div C = Output Voltage Ripple, 50mV/div TIME = 2ps/di = Qus/div CIRCUIT OF FIG. 1 VIN=+45V Ta= 425C MA AXLAN 3-1605V, -12V, -15V, and Adjustable inverting Current-Mode PWM Regulators LOAD CURRENT vs. SUPPLY VOLTAGE Tas 425C Cl 700 RCUIT OF FIG. 800 Vout = -5V = 500 z 400 Fa 3 300 4 S 200 Y 100 SUPPLY RANGE = 0 : 0 2 4 6 8 0 2 14 16 SUPPLY VOLTAGE (V) MAX739/MAX759 EFFICIENCY vs. LOAD CURRENT (BOOTSTRAPPED) 90 (Ty =425C CIRCUIT OF FIG. 1 LX = 33H MPP CORE poms V4=10V = 80 mS t 2 NJ V4= SV Fa} a Ww wo 70 | V+=4V 60 0 50 100 150 200 250 300 350 LOAD CURRENT (mA) MAX739/MAX759 EFFICIENCY vs. LOAD CURRENT (NON-BOOTSTRAPPED) 90 Ve215V oo od . | 80 ~ | = TV ven Vs = 6V 3 a Ss i 70 . i | a= 425C CIRCUIT OF FIG. 1 (x = 33H MPP CORE 60 [1 0 50 100 150 200 250 300 350 LOAD CURRENT (mA) MAAXIAN MAX736 EFFICIENCY vs. LOAD CURRENT (BOOTSTRAPPED) 80 B A = _ = "HARSS rm - Y V+=8.0V 3 6 vwe4sv NN Sos = V+ =5.0V 60 Ta=425C 55 | X= 10H Ll 0 50 6100 150 (200 250 300 LOAD CURRENT (mA) MAX736 EFFICIENCY vs. LOAD CURRENT (NON-BOOTSTRAPPED) | A Ta= 425C 75 ~< iX=10nH N 70 # 5 \ N\ a 6 \ V+ = 8.0] o i a0 \\ V+=5.5V SSP Veo 4 5V V+=5.0V sol _L_ | 0 50 6100 150 200 250 300 LOAD CURRENT (mA) PEAK INDUCTOR CURRENT vs. SUPPLY AND LOAD Ta= CIRCUIT OF FIG. 1 LX = 33H PEAK INDUCTOR CURRENT (A) ILoap = 300MA {LOAD = 100mA ILoaD = SOMA ILoAD = 10mA 0 0 2 4 6 8 10 12 14 SUPPLY VOLTAGE (V) 16 EFFICIENCY (%) EFFICIENCY (%) ON RESISTANCE (a) Typical Operating Characteristics (continued) rc 70 R 3 & s MAX737 EFFICIENCY vs. LOAD CURRENT (BOOTSTRAPPED) TA LX 2 = oa 80 120 LOAD CURRENT (mA) 160 200 MAX737 EFFICIENCY vs. LOAD CURRENT (NON-BOOTSTRAPPED) 6SZXVW/6EZXVW/LEZXVW/9SEZLXVWN 75 Ta=425C sree rN 65 KA NY 60 \ ' V+=5.5V V+=5.0V 55 V+=4.5V \ 50 deo 0 40 80 120160200 LOAD CURRENT (mA) SWITCH ON RESISTANCE vs. SUPPLY (DRV-) VOLTAGE (NON-BOOTSTRAPPED) I od DRV-= GND \ ' \ +125C |] 485C NNZZ 425C Ser 0 2 4 6 8 10 12 14 16 SUPPLY VOLTAGE (V) 181MAX736/MAX737/MAX739/MAX759 5V, -12V, -15V, and Adjustable inverting Current-Mode PWM Regulators Typical Operating Characteristics (continued) MAX736/MAX739/MAX759 MAX737 NO-LOAD SUPPLY CURRENT vs. NO-LOAD SUPPLY CURRENT vs. REFERENCE VOLTAGE vs. SUPPLY VOLTAGE (NON-BOOTSTRAPPED) SUPPLY VOLTAGE (NON-BOOTSTRAPPED) LOAD CURRENT 3) T 7 { = 425" = 425" Ta= 425C _ Ta= 425C _ Ta= 425C N s 1.230 v= 5000 < <= = = MN. ir = = 3 <4 1. z 2 x Fa . = a & L_ & = 1.220 > > 2 = 14215 & z | 2 5 S Oo a1 | 2 J vy 1.210 2 Vina S Lf > 5 2 az! 7 fB 1.205 =z =z # A 1.200 0 | 1.195 0 2 4 6 8 10 12 14 16 0 1 2 3 4 5 6 7 0 500 1500 2500 SUPPLY VOLTAGE (V) SUPPLY VOLTAGE (V} REFERENCE SOURCE CURRENT (yA) Pin Description PIN NAME FUNCTION 14-PIN DIP 16-PIN SO Positive Supply-Voltage Inputs. Connect all V+ pins together. Bypass with at least 1,13, 14 1,15, 16 V+ aQ.1pF capacitor close to V+ and GND pins. 2 2 SHDN Shutdown Control. V+ = normal operation, GND = shutdown. 3 3 VREF Reference Voltage Output = +1.23V. Supplies up to 125A for external loads. 4,6 4,5,6 N.C. No Connect. Not internally connected. 5 7 ss Soft-Start 7 8 cc Compensation Input. CC is the input of the error amplifier, and is held at virtual ground. For the MAX759, CC is connected to an external resistor divider. 8 9 Vout Output Voltage feedback terminal (actually an input). Connected to internal resistors (MAX736/737/739 only). Do not connect on MAX759. _ Negative Drive Voltage Input is the negative supply rail for the push-pull stage that 9 to DRV. drives the internal power FET. 10 11 GND Ground 11, 12 12, 13, 14 Lx Switch Output internal P-channel MOSFET drain. Connect all LX pins together. 3-182 MAAXIAA5V, -12V, -15V, and Adjustable inverting Current-Mode PWM Regulators INPUT (SEE TABLE 1) f eames 1 4a{/ IL Ve V+}-4 Cl o2 1.0uF 150uF __ 1 2) SHON vet 3 J C3 u 22uF 5] AAAMIAA 10 10H [| vaeF MAX736. |X AAA MAX737 1" = lhe. ux 5] eno}? =. D1 C4 = LS = O.1pFs g 13 F po | ne. DRV- pt Mead Se aay 7 8 cc Vout ir cst NON-BOOTSTRAPPED: INSTALL J3: ae 150uF BOOTSTRAPPED: INSTALL J2 PIN NUMBERS ARE FOR DIP. * SEE COMPONENT SELECTION GUIDE SECTION. **REQUIRED FOR BOOTSTRAPPED OPERATION. INPUT (SEE TABLE 1) yt: uj EL Ve TT ct oe 1g | THE 150uF SHDN ve pS - MAM |,, 1O,H to 33H VREF MAX739 Lx WNW] MAX759 = NO. xp ss eno Ho * 0 B pos ne. orv-}2 + ~5+iNeod gin SR] A ec Vout Oe |GET!) C8 R3t L 150uF NON-BOOTSTRAPPED:_ INSTALL J3; BOOTSTRAPPED: INSTALL J1 OR J2 (MAX759). PIN NUMBERS ARE FOR DIP. ***R5 NOT NECESSARY FOR COMMERCIAL TEMP RANGE OR LESS THAN 150mA OUTPUT CURRENT. * SEE COMPONENT SELECTION GUIDESECTION. USE Re AND Ra WHEN USING MAX759. **MAY BE REQUIRED FOR BOOTSTRAPPED - {33 OR COMMERCIAL TEMP RANGE OPERATION. ly. Sau USED IN TEST CIRCUIT. Figure ta. MAX736/MAX737 Standard Application Circuit (Through-Hole Components) figure 1b. MAX739/MAX759 Standard Application Circuit (Through-Hole Components) Table 1. Standard Application Test Circuit Parameters V+ Range (V) Device Output Voltage (V) Diode D1 Bootstrapped Non-Bootstrapped MAX736 4to86 4to8.6 -12 1N5818 MAX737 4to5.5 4to 5.5 -15 1N5818 MAX739/MAX759 4to11 4to 15 5 1N5817/1N5818 ee re Detailed Description Ve wn = Operating Principle __ 45 | O-tMF 33nF The MAX736/MAX737/MAX739/MAX759 are monolithic SHDN ver CMOS ICs containing a current-mode PWM controller C3" 4 14 and a 1.5A P-channel power MOSFET. Current-mode fe VREF x we control provides excellent line-transient response and AC 4) MAMIAA 113 10pH stability. The switch transistor is a current-sensing MOS- {Ne ee xr FET that splits off a fraction of the total source current for 5] yc, MAX7I9 1y [22] current-limit detection. " #01 Basic Application Circuits TNC. GND 4 a Figures 1a and 1b show the standard application circuits, C411 71 og 10 18 Fieeon using through-hole components, for the MAX736/MAX737 osprey 1 DRV- Ro" oureur and the MAX739/MAX759 respectively. The surface- ~ 3 g dl > 10k (SEE TABLE 1) mount standard application circuit is shown in Figure 2. cc. Your < 5 Refer to the Component Selection Guide section for 33yF application-specific circuit components. * SEE COMPONENT SELECTION 2 8 AS IN FIGURES 1a AND 1b. . PIN NUMBERS ARE FOR REQUIRED FOR BOOTSTRAPPED CAPACITORS ARE SURFACE-MOUNT TANTALUMS. Figure 2. Standard Application Circuit (Surface-Mount Components) MAMAXILAA 3-183 6SZXVW/6EZLXUVW/ZEZXVW/9ELXVWNMAX736/MAX737/MAX739/MAX759 -5V, -12V, -15V, and Adjustable Inverting Current-Mode PWM Regulators Vin (SEE TABLE 1) Ct + x c2 SHON ve OVERCURRENT COMPARATOR - SLOPE /) 4 BS | COMPENSATION RAWP <J > Z Your Rsense & ras emt Lp 7 [SNH] Vout R (Set Z XK ABLE 1) 1.23V 7 . BANDGAP | 7] nL T REF = 4 05 ! 165KH2 T iM = Ost Mino i i #35% - MAX737 MAX739 pS ol MAX759 q i C4 SS CLAMP uvLo av =~ GND * OPTIONAL **EXTERNAL COMPONENTS WHEN USING THE MAX759 Figure 3. Detailed Block Diagram Bootstrapped/Non-Bootstrapped Modes The most important decision in configuring a MAX736/MAX737/MAX739/MAX759 circuit is whether to operate in bootstrapped (DRV- connected to a negative voltage) or non-bootstrapped (DRV- connected to GND) mode. The DRV- connection determines the input volt- age range, available output power, and quiescent supply current as described in the Typical Operating Charac- teristics and Electrical Characteristics. DRV- connects to the negative supply rail of the driver stage that drives the internal power MOSFET gate. Increasing the negative voltage applied to DRV- reduces MOSFET on resistance, but the supply current is higher due to the higher gate- source voltage swing. Do not exceed the Absolute Maxi- mum Ratings specification for the voltage difference between V+ and DRV-(17V). Intermediate bootstrap voit- age levels appropriate for the MAX736/MAX737/MAX759 are obtained by using a zener shunt (Figure 4). Continuous-/Discontinuous- Conduction Modes The maximum duty cycle is 90%, so the circuit can be operated in continuous-conduction mode (CCM) or dis- continuous-conduction mode (DCM) by selecting higher or lower inductor values. In CCM, the inductor current never decays to zero. In DCM, the inductor current slope is steep enough so it decays to zero before the end of the transistor off time. CCM allows the MAX736/MAX737/ MAX739/MAX759 to deliver maximum load current, and is also slightly less noisy than DCM, because it doesnt exhibit the ringing that occurs when the inductor current reaches zero. However, DCM allows for lower output filter capacitor values because there is no continuous-feed- back path through the inductor. MAXUM 3184 |-5V, -12V, -15V, and Adjustable Inverting Current-Mode PWM Regulators Vin (SEE TABLE 1) D1 ~Vour Ve (SEE TABLE 1) Vour=1.23V fz] R4 C5 R4 * OPTIONAL Figure 4. MAX736/MAX737/MAX759 Zener-Bootstrap Scheme AC Compensation Primary compensation for feedback stability is provided by a dominant pole created by the filter capacitance and load resistance. The ESR of the output filter capacitor introduces a zero in the loop response, which tends to destabilize the loop. In the Standard Application Circuits (Figures 1a and 1b), the 150uF output filter capacitor (C5) should have a maximum ESR over temperature of 0.5Q in order to deliver full load at the minimum supply voltage. Operation at higher input voltages with lower inductor values (low enough to force the circuit to operate in discontinuous- conduction mode) or at lower output current than the full load capability reduces the need for large filter capacitors. Surface-mount capacitors with very low ESR are available. Consequently, smaller capacitance values are adequate (see Figure 2). Soft-Start Buffer The voltage applied to SS determines the peak switch-cur- rent limit (see Typical Operating Characteristics). A capacitor attached to SS ensures an orderly power-up. SS is pulled up to VREF internally through a 1MQ resistor. The maximum current limit can be fixed externally at a lower than normal value by clamping SS to a voltage less than VREF. An SS cycle is initiated whenever either an under- MAXUM Figure 5. MAX759 Adjustable Output Voltage voltage lockout or overcurrent fault condition triggers an internal transistor to discharge the SS capacitor to ground. Note that the SS capacitor should be at least 10nF. A typical value is 0.1pF. When peak inductor cur- rents at start-up are small, this capacitor may be omitted. Undervoitage Lockout The undervoltage lockout allows operation for supply vol- tages greater than 3.7V typ (4V guaranteed), with 0.25V of hysteresis. Internal control logic holds the output power MOSFET in an off state until the supply rises above the undervoitage threshold, at which time an SS cycle begins. Inductor Selection Practical nominal inductor values are in the 10H to 33nH range (see Component Selection Guide section). Low inductor values force discontinuous-conduction modes (see the Continuous-/Discontinuous-Conduction Modes section). The inductor must have a saturation (incremen- tal) current rating greater than the peak switch current obtained from the Peak Switch Current vs. Load Current graph in the Typical Operating Characteristics. The MAX736/MAX737/MAX739/MAX759 contain slope com- pensation circuitry that improves currenttoop stability. Slope compensation is optimized for inductance values in the 10H to 33H range. 3-185 6SZLXVW/6EZLXVW/ZELXVIW/9EZLXUWMAX736/MAX 737/MAX739/MAX 759 -5V, -12V, -15V, and Adjustable Inverting Current-Mode PWM Regulators INPUT wv, INPUT 13,14 9V 10 21V O1uF => ch Ve + = DIRE S= 47uF =~ | AA AXLAA LX Te tsour = = | Mass T waKGoot ON/OFF ~] SHON DRV- Ve V4 = 1a 0.047uF saan urPuT 10 _ 047 Fy 14 25pH GND VRE > OUTPUT rt FE var MAX739 Xx = | veer Ov 70 -24V o a NC. LX neste edur Ht 30mA 1 \t- ss GND T 6vT = -1NE. DRV- |} 0.047 uF >= te cc = O.1uF Vout f-_ tOnF CONTRAST Tv = ADJUST = + 10nF L1 = GOILTRONIGS CTX100-1 OR MAGNETICS, INC "KOOL-MU" 77030-A7 30 TURNS AND 30 TURNS 26 AWG PIN NUMBERS ARE FOR DIP Figure 6. MAX739 +5V Step-Down Application Figure 7, -24V LCD Power Supply Adjustable Output Refer to the MAX7339 evaluation kit manual for the recom- Adjust the MAX759s output voltage from OV to -15V by selecting the appropriate external resistor divider (Figure 5). Output voltages beyond -15V require a transformer to protect the power MOSFET from overvoltage. With R4 feedback resistor (5kQ to 15kQ), a compensation capacitor (typically 10nF) from the output to CC gives best transient-response characteristics. Be careful to observe the Absolute Maximum Ratings on the difference between input voltage and output voltage. Reference Bypass Capacitor When the input voltage exceeds 11V (i.e. MAX739/MAX759 in non-bootstrapped mode) use 0.047yF for reference capacitor C3. In bootstrapped mode, refer to the Component Selection Guide section. With the MAX736/MAX737, use 4.7uF to 22nF for the reference bypass capacitor. 22uF provides the best stability when large output currents are required. Printed Circuit Layout and Grounding Good layout and grounding practices will help achieve low-noise, jitter-free operation. Minimize wiring lengths in the high-current paths, especially the distance between the inductor and the return leads of the filter and bypass capacitors (C2 and C5 of Figures 1 and 2). These high- current ground connections should be brought toa single common point (a "star" ground). Place a low-ESR bypass capacitor directly at the V+ and GND pins of the IC (C1 in Figures 1 and 2). 3-186 mended layout. Component Selection Guide The following guidelines are for component selection when the MAX736/MAX737/MAX739/MAX759 are operated in bootstrapped mode (i.e. DRV- connected to -5.6V (MAX736/MAX737) and DRV- connected to VOUT (MAX739/MAX759)). For non-bootstrapped applications see Reference Bypass section. Surface-Mount Component Selection (see Figure 2) MAX739/MAX759 Over the extended temperature range, use the following component values: L1 = 10yH, C1 = 0.1pF, C2 = 33uF, C3 = 3.3uF (tantalum), C4 = 0.1pF, C5 = 33pF. When VIN = 4.5V, this circuit provides 200mA (VouT = -5V). Over the commercial temperature range, reference capacitor C3 is not required for load currents less than 150mA. MAX736/MAX737 Over both the commercial and extended temperature ranges, use the following component values: L1 = 10H, Ci =0.1pF, C2 = 33pF (16V), C3 = 22uF (20V), C4 = 0.1pF, C5 = 33uF (20V). C2 and C5 must be low-ESR capacitors such as those available from Matsuo and Sprague. When VIN 2 4.5V, this circuit provides 100mA. When V+ is 2 6V, the MAX736 provides up to 125mA of output current (note that 6V exceeds the input voltage range of the MAX737). MA AXIAA5V, -12V, -15V, and Adjustable inverting Current-Mode PWM Regulators Table 2. Component Suppliers Through-Hole Japan: Phone (03) 3607-5111 PRODUCTION METHOD INDUCTORS CAPACITORS Sumida Matsuo USA: Phone (708) 956-0666 USA: Phone (714) 969-2491 FAX (714) 960-6492 Japan: Phone (03) 3607-5111 CDs. FAX (03) 3607-5428 Japan: Phone (06) 332-0871 D4-330 (33H) 267 series Surface Mount CD54-100 {3 OwH) Sprague Electric Company Coiltronics USA: Phone (603) 224-1961 Phone (305) 781-8900 FAX (603) 224-1430 FAX (305) 782-4163 595D Series CTX 100 series Sumida Sanyo Os-Con USA: Phone (708) 956-0666 USA: Phone (619) 661-6322 Miniature Japan: Phone (0720) 70-1005 FAX (03) 3607-5428 FAX (0720) 70-1174 RCH654-330 (33H) OS-CON series RCH 108-330 (33,1) Low ESR Organic Semiconductor Nichicon Phone (708) 843-7500 FAX (708) 843-2798 Pree 5 ) 556 tb sess El ione (516) 586-5566 ow lectrolytics Through-Hole FAX (516) 586-5562 RL 1284-33 (33H) United Chemi-Con Phone (708) 696-2000 FAX (708) 640-631 1 LF series For wide temperature applications using through-hole components, organic semiconductor capacitors are recommended (C2 and C5 in Figure 1). These capacitors maintain low ESR across their operating temperature range. Through-Hole Extended Temperature Range Component Selection (see Figure 1) MAX739/MAX759 Use the following component values: L1 = 18H, C1 = ipF, C2 = 150pnF (OS-CON), C3 = 22uF (tantalum), C4 = 1.0uF, C5 = 220uF (OS-CON), R5 = 4.7MQ. This circuit provides up to 250mA (VouT = -5V) when VIN 2 4.5V, and up to 300mA when VIN 2 6V. Note that this is the only configuration that uses resistor R5. For output currents up to 150mA, C4 can be reduced to 0. 1pF and R5 can be omitted. MAX736/MAX737 . Use the following component values:L1 = 10yH, C1 = 1.0pF, C2 = 220uF (OS-CON), C3 = 22uF (tantalum), C4 =0.1pF, C5 = 100uF (OS-CON). When VIN 2 4.5V, the circuit provides 100mA. When V+ is 2 6V, the MAX736 provides up to 125mA of output current. MAAXLAN Through-Hole Commercial Temperature Range Component Selection (see Figure 1) MAX739/MAX759 Use the foilowing component values: L1 = 10nH to 33H, C1 = ipF, C2 & C5 = 150pF (35V, Nichicon), C3 = OWF to 2.2uF, C4 = 0.1pF. With L1 = 10WH and C3 omitted, when VIN 2 4.5V, the circuit provides up to 200mA. When VIN 2 6V, the circuit provides up to 250mA. When L1 = 15pH to 33pH, C3 = 2.2uF, and VIN 2 4.5V, the circuit provides 250mA. When VIN is 2 6V, the circuit provides up to 300mA. If C3 is not used, the output current capability is reduced by approximately 50mA. MAX736/MAX737 Use the following component values: L1 = 10pH, C1=1.0uF, C2 & C5 = 150uF (35V, Nichicon), C3 = 22uF, C4 = 0.1pF. When VIN 2 4.5V, the circuit provides 100mA. When V+ is 2 6V, the MAX736 provides up to 125mA of output current. 3-187 6SZXVW/6GELXUW/ZEZLXVW/9EZLXUWNMAX736/MAX737/MAX739/MAX759 5V, -12V, -15V, and Adjustable Inverting Current-Mode PWM Regulators Applications Information +5V Step-Down Application The MAX739/MAX759 can operate as step-down (buck) regulators with a positive output (Figure 6). Because the supply current flows into the load, this +5V step-down circuit offers good efficiency even at low load currents: 60% to 85% from 3mA, up to the fulltoad capability of 1A. It requires a minimum load of 3mA. The input voltage range is QV fo 21V. if the input does not exceed 15V, ground DRV- for higher efficiency and remove the zener. -24V LCD Power Supply The LCD power supply circuit of Figure 7 generates an adjustable negative voltage for powering small LCD dis- plays, and will deliver 30mA at -24V. Typical efficiency at 30mA is 80%. A simple autotransformer safely steps up the output voltage beyond the voltage breakdown rating of the internal power MOSFET. The autotransformer (tapped inductor) specified on the schematic is a minia- ture (0.25" diameter) toroid. This autotransformer ap- proach is slightly better than a flyback transformer due to superior magnetic coupling and a reduction in the num- ber of turns. Refer to the MAX759LCDKIT-SO power supply evaluation kit manual and Application Note. _. Ordering Information (continued) PART TEMP, RANGE PIN-PACKAGE MAX739CPD 0C to +70C 14 Plastic DIP MAX739CWE OC to +70C 16 Wide SO MAX739C/D 0C to +70C Dice* MAX739EPD -40C to +85C 14 Plastic DIP MAX739EWE -40C to +85C 16 Wide SO MAX739MJD -55C to +125C 14 CERDIP* MAX759CPD 0C to +70C 14 Plastic DIP MAX759CWE 0C to +70C 16 Wide SO MAX759C/D 0C to +70C Dice* MAX759EPD -40C to +85C 14 Plastic DIP MAX759EWE -40C to +85C 16 Wide SO MAX759MJD ~ -55C to +125C 14 CERDIP *Contact factory for dice specifications. *Contact factory for availability and processing to MIL-STD-883. 9-188 Pin Configurations (continued) TOP VIEW ve [ay jie) vs SHON [2 5] vs vnet (3) aaxrag [ta] x MAX737 NOL axr3g FSI NC. [5] MAX759 Fa] Lx NC. 16 11} GND ss [7| 10) DRV- ce [BI 19] Vour WideSO Chip Topography (2.946 mm) ? NOTE: TRANSISTOR COUNT: 274; CONNECT SUBSTRATE TO V+. MAAXLAA