-'l-Micro Linear --- Battery Power ControllC GENERAL DESCRIPTION FEATURES The ML4862 is a complete solution for DC to DC conversion and power management in multi-cell battery powered portable computers and instruments. Several advanced techniques are incorporated in the IC for the highest possible systems efficiency. • Two synchronously rectified, 100kHz buck regulators for 5V and 3.3V outputs The 5.0V and 3.3V main regulators in the ML4862 each control a synchronously rectified buck regulator, using twO N-channel MOSFETs. This allows high conversion efficiencies (90% or greater). Bias for all N-channel MOSFETs in the system as well as the input for the 12V regulator for programming EEPROMs comes from an auxiliary winding on the buck regulator choke. The ML4862 also contains 3 outputs to drive external Nchannel MOSFETs to power down disk drives and memory under control of external logic. Automatic switch-over to battery operation is also provided when the charger is removed. A IlPower 5V linear regulator and low battery indicator are provided for the power monitoring logic. • Regulation to ±3% maximum; provides 2% PCMClA switch matrix margin • Low cost all N-channel MOSFET switching • Three logic to N-channel gate drive translators for power management • IlPower SV standby linear regulator to run power management logic • Output and logic for N-channel MOSFET to disconnect battery when charger is connected • 12V auxiliary output available with On/Off Control for E2 memory programming • low battery detect comparator • Wide input voltage range (5V to 20V) BLOCK DIAGRAM '---------'='-"-"-j7!-J"JI,fv-J __ . I I JI ML4862 ~ CONFIGURATION ML4862 32-Pin (532) soic 12VOUT IT 31 VADAPTfl VGS VI" ON/OFF BATTEIYLOW FOBKA VIAT COMPA FOBKB ENABLE A CQMPB OUT2A GND ON/OfF 12 OUT2B PWRGNO OUTIB OUTlA SVOUT V,N ISENSEB ISENSEA SWI ,. SW2 SOUll .. IS SWl VCT SOFTSTART SOUT2 ..r-- ~'-1."""' soun TOP VIEW PiN DESCRIPTION FUNCTION PIN' NAME FUNCTION RT Timing Resistor which setsoscillator frequency 17-19S0UTJ-1 MOSFET gate drive outputs for power management 1 VADAPTER Input to sense whether adapter is active. When this pin is above VBAT, VG5 goes low. 3 VG5 Output to drive N-Channel MOSFET gate to switch battery out when adapter is present I'I!II' NAME 4 BAITERY LOW A logic low level indicates the voltage on VBAT is below 2.5V. This is an open-collector output. 5 VBAT Battery Comparator input 6 FDBK B Voltage Feedback for buck regulator B 7 COMPB Buck Regulator B frequency compensation terminal 8 ONIOFf 12 A logic high turns on the 12V linear regulator 9 OUT2B 5V Buck Regulator Synchronous Rectifier Output 10 OUT1B 5V Buck Regulator Switch Output 11 5VOUT Output of the IlPower 5V regulator. Normally used to power external management circuits and logic 12 ISENSEB Current Sensing for buck regulator B current limit 13-15SWl-3 16 VCT Inputs for power management MOSFET gate drivers Boosted voltage to drive N-Channel O ......... c ..., .....~ ; ........ " ...... , ..,\'l: . . . . . , ... r .. .-~.,'~t'"" .. 20 50FT START Connected to a soft start capacitor 21 ISENSEA Current Sensing for buck regulatorA current limit 22 VIN Input from Battery or AC Adapter 23 OUT1A 3.3V Buck Regulator Switch Output 24 PWRGND Power Ground 25 GND Logic and signal Ground 26 OUT2A 3.3V Buck Regulator SynchronouS Rectifier Output 27 ENABLE A A logic low disables Buck Regulator A's Synchronous Rectifier output 28 COMPA Buck Regulator A frequency compensation terminal 29 FDBKA Voltage Feedback for buck regulator A 30 ON/OFF A low on this pin disables alilC functions except the low battery detection comparator, the linear 5V regulator and the 2.5V reference,and puts the IC into a low current consumption mode 31 VREF Buffered 2.5V reference output 32 12VOUT Output of the 12V linear regulator ML4862 ....ABSOLUTE MAXIMUM RATINGS ~ute maximum ratings are those vanes beyond which the device could be ptrmanently damaged. Absolutemaximum ratings are stress ratingsonly and wnC1ional device-operation is not unphed, Voltage on any pin OutputCurrent, Source or Sink (pins 9,10, 23, 26) pulsed VGS Source Current VGS Sink Current 12V Linear Regulator Output Current IV Linear Regulator Output Current logic Inputs (pins 8,13,14,15,27,30) -O.3V 'SENSE Inputs (pins 12 ,21) - 36V 300mA 20mA 200mA 200mA SOmA to 5.5V VIN Comparator Inputs (pins 2, 5) ..•..•.............. -O.3V to 5.5V Junction Temperature ...............•............................. 150°C Storage Temperature Range ......•.............. -65°C to 150°C Lead Temperature (Soldering 10 Sec.) 260°C Thermal Resistance (OIA) 60°C/W OPERATING CONDITIONS Temperature Range O°C to 70°C VIN Voltage Range .................•...................... 5AV to 24V VCT Voltage Range VIN -0.5 to 3SV ELECTRICAL CHARACTERISTICS Unless otherwise specified, TA = Operating Temperature Range, VIN = 12V, VCT = 22V, RT = 200kn, ILOAD(12V) < 1OmA (Note 1). PARAMETER CONDITIONS UNITS Oscillator Initial Accuracy TA=25°C Accuracy Over Temperature Dead Time 102 90 50kn S RT S 300kn Maximum Duty Cycle Voltage Stability 95 105 kHz 110 kHz 400 800 1000 ns 90 94 98 % % 2 6V S Y'N <S 20V Error Amplifiers Input Offset Voltage 2 10 mV Inpul BiasCurrent 10 200 nA 0.6 V V Output High Voltage lOUT= -2mA. TA = 25°C Output Low Voltage lOUT= 15I1A.TA = 25°C Source Current VOUT= 2.5V -5 -7 Sink Current VOUT= 2.5V 10 50 II A 675 kHz 20.4 V 2.8 Gain·Bandwidth Product 2.95 rnA I i High Side(OUll) Outputs ~utput High Voltage lOUT= -20mA Output Low Voltage lOUT= 20mA 19.5 0.2 0.5 V I ! Lo... SIde (OUT2) Outputs Output High Voltage lOUT=-20mA Output Low Voltage lOUT= 20mA ..~ M L4862 . LECTRICAL CHARACTERISTICS (Continued) PARAMETER I CONDITIONS w I MIN I TVP I MAX Soft Start and Current Limits V IN-250 T hreshold Voltage Bias Current SoIt Start 'DISCHARGE -lie ference ~ , I I 1 VIN-200 VIN-150 mV- i 27 50 IIA- I ~ -13 -20 2 6.2 VISENSE = VIN - 200mV SoIt Start ICHARGE --- mA- o utput Voltage TA = 25°C, IpIN3! = -1 mA 2.5 2.55 V- Line regulation 5.4V < VIN < 20V, IpIN31 $ -lmA 0.3 2.0 mV/V- l'otal Variation Line, load and temp. 0.7 2.45 , I IIA ( I I I r % l 2V Linear Regulator o utput Voltage 10=60mA Line regulation 16V < VCT < 30V Drop Out Voltage (VGT-VoUT) 10= lOmA Load regulation 1llJ.tA< 'a < 11.25 12 12.75 0.01 60mA . V %IV 2.3 2.7 V ±1.6 ±3.2 % 5.0 5.15 V 1 5V Linear Regulator 4.85 Output Voltage lOUT= lmA Input Voltage VoUT ~ 4.85V, 10 = 1mA Line Regulation 5.4V < VIN < 20V, 10 = 1rnA 0.75 1.5 % l.oad Regulation 1llJ.tA < 10 < 25mA ±1.5 ±3 % V 6.2 vBAT and VADAPTER Comparators Input Bias Current VIN = 20V Input Offset Voltage 200 nA ±40 mV 0.4 V Battery Low VOL lol = 200~A Battery Low VoH 30m pullup to 5V 4.5 5.0 V VG5 Source Current Vcs> 12V -5 -15 mA VG5 Sink Current Vcs = 12V 85 mA Power Management Drivers (Pins 13-15, 17-19) Source Current VSOUT = 10V --8 -15 -30 Sink Current VSOUT= 10V 8 15 30 Output High Voltage ISOUT=-20~ 14.5 15.6 Output Low Voltage ISOUT=20~ 0.16 ~~V V_ Logic Inputs (Pins 8, 13-15, 30, 27) Logic Low (VILl (except Pin 8) IIN~-5~ 1.1 V Logic Low (Vll) Pin 8 IIN~-5~ 0.6 V Logic High NIH) IIN~5~ V 2.5 SupplyCurrent SleepMode, TA = 25°C liN + IGT 115 180 ~ liN Run Mode, TA = 25°C 6 10 mA IGT Run Mode, TA = 25°C 4 6 rnA Note 1: limits are guaranteed by 100% testing. sampling, Of correlation with worst-case test conditions - 0.4 - ML486: FUNCTIONAL DESCRIPTION roWER DOWN MODES BUCK REGULATORS The Ml4862 operates in either a powered down mode or un mode according to the state of the ON/OFF pin ble 1). When the ON/OFF pin is high, the Ie is in the I ~ mode and the various IC sections are functioning ~cording to the logic ~h?wn in Table 1. When the ON/ OFF pin is low, the IC IS rn the standby mode and only the power 5V linear regulator and 2.5~ reference are on. All ~ate drive outputs are low. The 5V linear regulator then ~vides the power to run the system's power management logic. The two buck regulators (Figure 1) are synchronously rectifying voltage mode PWM regulators capable of bein used over a wide variety of loads and input voltages. Th use of synchronous rectification improves system efficiency by reducing the fixed drop associated with the "free-wheeling" diode in conventional regulators. These regulators drive all N-channel power MOSFETs, to achie lowest RDSION) at the lowest cost. In order to drive the MOSFET gates adequately, a Vcr supply must be provid~ which is higher than the battery voltage by an amount sufficient to provide full enhancement voltage to the MOSFETs. This can be generated by using a winding fror the 5V buck regulator as shown in Figure 2. Vcr must nil be lower than O.5V below VIN. 1/ TABLE 1. ML4862 POWER DOWN MODES MODE ONIOO ENABLE A ONIOO12 Sleep 12V 0 X X Micro Power 5V Reg Only l30llA 1 X 1 12V linear Regulator on 600 A Partial 1 0 0 Synchronous Rectifier Drive for Reg. A Disabled, All Other Functions Running 8mA 0 All Functions Enabled lOmA Run Run FUNCTION TOTALSUPPLj CURRENT RT OSCILLATOR Fl RFI Rl C1 Q COMP RF2 Ql l - - - - - - - - - 1 Q F2 sl-----< • Buck R"8""'lo, It. only Figure1. BuckRegulatorBlock Diagram. . . Regulator A includes a pin to disable the 'lllhronous rectifier driver (GUT2A) to prevent pulling .."t out from the output, allowing the inductor current lllfIcome discontinuous at light loads. iktion of the external MOSFETs, output inductor and QlllCitor determine the output capabilities of the ,.lator. Output voltage is set by RF1 and RF2 where v. - 2.5x(RF1+RF2) OUT - RF2 (1) lIf5hort circuit current limit is set by external resistor Rs. L 'SHORT CKT = 0.2 R s (2) (fiG discharged whin tha regulator is off or when the ~e across Rs exceeds 200mV. F2 ensures that Css is tiJrdischarged. This circuit provides reliable output _ circuit protection with very little power wasted in the _ng element. The error amplifier's output voltage is !iaiIed to the voltage on the SOFT START pin. When Css i>tiK:harged, the regulator's duty cycle is O. lOQC TO MOSFET GATE DRIVERS 1lIis section provides a convenient translation stage for ~g on low cost external N-Channel power MOSFETs _power management. SOUT sources current when SW ilhigh and sinks current when SW is low. These outputs . .limited to small currents to switch these MOSFETs liewIy, reducing the transients to the main regulator OIIIput from switching discharged capacities. Additional slow down of the switching may be achieved by adding GJPaCitance form the SOUT pins to GND. MTJERY DETECTION AND ADAPTER SWITCH These two functions are provided by comparators. The V"DAPTER comparator goes high when the VBAT pin is lligher than VADAPTER, so that the system can run from the battery without the loss associated with a diode. When !heAC adapter is plugged in, the voltage on pin 2 goes fNgh, VG4 switches low, and the system runs from the AC ~pter. A low battery comparator with an open collector ClUtput is also provided to monitor battery level. nv UNEAR REGULATOR The 12V regulator includes a shut-off pin. Since this ~ulator takes its input from VCTcare should be taken to ensurethat the regulator does not cause excessive heat in the IC when used with high values of VIN. APPLICATIONS BUCK REGULATOR INDUCTOR Inductors are specified with three main parameters; inductance (l.), maximum current (I0UTIMAX)), and Dc resistance. (Rl .) Inductance for a given set of requirements can be calculated with the following: l = (v.IN- v.OUT) V1NxFxAI VOUT Assuming that the desired ripple current: By choosing the ripple current to be 40% of maximum output current (IMAX), below 20% of 'MAX, the inductor will actually pull current out of the output capacitor during part of the on time of the low side MOSFET. The result of this current "shuttling" is a slight increase in losses. Buck regulator A includes the ability to disable the synchronous rectifier output to avoid current shuttling at light loads and thereby operate using conventional rectification. To avoid inductor saturation, the maximum output current of the regulator should not exceed 80% of the current rating of the inductor, especially when using ferrites, which have a "hard" saturation characteristic. Powdered iron cores saturate more softly and may therefore be pushed closer to their rated currents. DC resistance of the inductor sets up its conduction loss. For the same size package DC resistance decreases as inductance is decreased. It is a good rule of thumb to select the DC resistance of the inductor to be 1.4 of the sum of the on resistance of the two output MOSFETs. This setsup conduction losses evenly among the power components. IJ, A ir h ~ 1 ML48b2 ..- VeT GENERATION FREQUENCY SELECTION AtwO to one secondary winding from the SV main output Frequency is set by the resistor RT,which establishes the charge current for the internal capacitor. Since the discharge current is a constant, the dead time of the oscillator is constant. Therefore the maximum duty cycle increases a the oscillator frequency decreases. For low input voltage applications, a lower switching frequency may be required to maintain regulation at minimum input voltage. inductorwill provide the gate drive voltage needed for high side switching (Figure 2). Because one end of the winding is tied to the input, the secondary voltage will be 10V above the input. When specifying the inductor, the maximum current rating of the inductor is the sum of the peak main output current and turns ration multiplication ofthe maximum secondary current only if both outputs draw maximum current at the same time. Depending on IGT load requirements, the inductor current rating may be specified for maximum main output current without including the secondary current requirement. 250 , 200 i\ i! CIGT) IS . ~ 150 " ~ .. r-, !!l 01 gloo ~ l2 -= 50 • + o o 50 100 ISO 200 250 lOG ITOdl) Figure 3. Oscillator Frequency YS. RT' Figure 2. Generating VGT Bias Voltage. A lower switching frequency may also improve efficiency. Losses are comprised of: AC Losses: Inductor Core MOSFET Switching MOSFET Gate Drive Current DC Losses: Inductor 12R MOSFET J2R OS(O N) Capacitor ESR At lower frequency, AC lossesare reduced proportionately. However the inductor's conduction lossesincrease for the same inductor size since inductance must increase proportionately to maintain the same amount of ripple current. Efficiency can be improved if inductor size is allowed to increase to allow more copper in the windings. ML4862 125 100 I""" e- V ! ~ 75 ~ ;: SO . 120 150 -- V .-V ~ V V 7 100 io"" ~ 80 V / I.... !~ 60 ./ ;: ./ 40 ~ tFALL tfAlL Ol...,....o' 25 o ~ / IV"'" 500 1000 o 1500 500 LOAD CAPACITANCE (pF) 1000 1500 LOAD CAPACITANCE IpF) Figure 4. OUTl Rise and Fall Time vs. Load CLOAD. Figure 5. OUT2 Rise and Fall Time vs. Load CLOAD. 12.5 8 -... ~ 12.0 II.5 ~ ~ 11.0 < g ... --f\ ~ '" ::> '" u \ 10. 5 10. 0 8 ~ ~ 100 18 1~ 1~ .=. a _l""' z ;; 6 5 10 lOUT (mA) 20 15 V'NVOLTAGE Figure 6. 12V Regulator Load Regulation. Figure 7. Supply Current (lIN) vs. VIN Voltage. 160 !i ... . t 51-----Ir-----I-:::iiI',;r.~-_1 / ::> u a 41- -+ -+ ,. VCT VOlTAGE (V) r-:..... _.... 0 C", ..•.• I / ./ ~ ~ 3.,,5---~:__---~---~ 10 15 20 V ./ 100 5 10 15 V,N VOlTAGE (V) 20 ~ COMPENSATION Proper compensation can be accomplished in many ways. The simplest compensation scheme (fig. 1 without C1) ses resistive feedback (R1) around the error amplifier. ~hiS reduces the gain of the op-amp which is in the overall loop's feedback path. This sets the overall loop gain to allow the loop's unity gain crossover to occur after the zero created by the ESR of the output capacitor has laken effect. This influences the two pole roll off created by the output inductor and the output capacitor providing the phasemargin required to keep the loop stable under all conditions. Rl/RFI setsthe gain (Av) of the loop. Based on the following assumptions a gain of 5 is sufficient for any range of input voltages: 1. Co=IOOIlF per 500mA of maximum output current. 2. Inductor ripple current is 40% of maximum output current. J. Load capacitance (Cl ) is not more than output capacitance (Co). Load capacitance is capacitance that gets switched in and out when loads are switched in and out and CO is the permanent output capacitance. 4. ESR of the total output capacitance is within the limits indicated in Table 2. Maximum ESR shown is for medium input voltage range (9V to 18V). Higher input voltage range (12V to 24V) requires lower limits (about 30%) for the maximum ESR allowed. Lower input voltage range (6V to 12V) allows higher (40%) maximum ESR limits. 5. Table 2 is for 100kHz operation. At lower switching frequency maximum ESR must be iower by a linear ratio. (i.e. at half the frequency maximum ESR must also be half). ESR (mQ) more than 0.5V. 05 can be eliminated if 02 is replaced by a Schottky. 04 and 03 are required to avoid negative currents from being pulled from the substrate of the Ie. These diodes can be replaced with 1N148's on the gates of Q2 and Q4 if a damping resistor is used from the gate to the Ie. 06 and 07 enhance the efficiency of the regulator by a small amount (about 1%) by preventing th MOSFET body diodes from turning on during the time when both halves of the MOSFET bridge are off. The energy which would be used for the reverse recovery of these body diodes is greatly reduced by using Schottkys. 01 can be either a conventional silicon rectifier or Schottky diode depending on efficiency vs. cost considerations. Resistors RIO and Rll are 20ma resistors which can be 1 made with a small length of wire or a PC board trace. C15 and C14 may be necessary to overcome the inductance in the sense resistor and are typically O.IIlF. C12 can be implemented using two IOOIlF tantalum capacitors in parallel or a 200llF electrolytic capacitor with a O.IIlF ceramic in parallel. C13 can be implemented in a similar fashion. MOSFETs Ql-Q4 should be rated to withstand the ~ maximum input voltage. Their on resistance will directl impact conduction lossesand therefore efficiency. For ; board space considerations, the littleFoot® series of ! MOSFETs provide a good trade-off between density and RosO N ' ! The inductor manufactures listed above can be reached Coiltronics (305) 781-8900 Sumida Electric (708) 956-0666 MAX 30 175 1 15 75 2.5 8 40 5 95 rl-1:::::l==+::::C:~ . ~ as u ~ o Table 2. Recommended ESR Values for 100kHz Operation. $ 80 75 Regulation can be greatly improved with a capacitor (Cl) placed in a series with the feedback resistor. Its value should be high enough to be no longer a factor at high frequency. 70 L-_.J..._...L.._......_--'......_ .....-~. 12 4 & a 10 o (1 can be calculated as: OUTPUT POWEI (w) > ~loCo(MAX) C,_ 1 Careful design of the inductor can improve efficiency by trading off cost and size. OUTPUT CURRENT (MAX) MIN I' RFI Several of the components in Figure 11 may not be r'.r., , t; ~~ ~I _J _I· , f I r Figure 10. System Efficiency vs. Output Power. The efficiency measurements taken for Figure 10 were measured with 1/3 of the output power delivered by the ., ")\f ~-_ •. I_._~ --...4 ,/') ""I ....... ,.. ,"".~ ...... ,t r"'f"'., ...... '" ,...I,..I; •. ,...."".... th,..., ML4862 -------------------------------6TO lOV ,. o D ...C "'DMTER D VAD4rTEI D ML4862 VGS GND SOUTl SOUT2 SOUl] SWI l SW2 SW] POWER MGT LOGIC J B...nERYLOW ON/OFF ON/OFF 12 EN.\BLE... SVOUl :;PO VI" 12VOUT All Capacitors in jJF, Schottky Diodes are 1NS817 except 06. are 1NS818 or lN5819 Figure 11. ML4862 Typical Application. D1~ ...... . - ML4B DESIGNATOR DESCRIPTION PART NUMBER (14, C15 O.lIlF, 50V (optional) see text 3A, 30V Rectifier see text -01 02 100mA, 50V (min) Rectifier 1N4148 03-D7 Schottky Diode 1NS817or M8RS130T3 11 471lH,lA Sumida CRD12S l2 5OIlH,1.5A Coiltronics CTXOS-11209-1 Ql-Q4 N-Channel Power MOSFET MTD10NOSE Q5-Q7 N-Channel Power MOSFET MMDF4N02 Q8 N-Channel Power MOSFET Si9410 RlO, R11 0.020 see text hble 3. Circuit Values for typicalapplication (Figure 11). I ~ A lC ~ " TO;~*l U Table of Contents }T#I ~ 1&ft. MfJlE( h"dtJ! e?fi«. PAGE SECTION s - Selection Guide SECTION' - ,1 BUS PRODUCTS . ..... , ML6500 Programmable Adaptive Clock M anager (PACMan™l : ML6S00EVAL Programmable Adaptive Clock Manager (PACMan™l Evaluation Kit ML6508EVAL Programmable Adaptive Clock Manager (PACMan™) Evaluation Kit ML6506 Programmable Adaptive Clock Manager (PACMan™) 6-1 .. 6-3 . 6-18 . 6-18 .. 6·19 .. 6-34 ML6509 Active SCSI Terminator ML6509EVAL Active SCSI Terminator Evaluation Kit MLti51 0 Series Programmable Adaptive Clock Manager (P''CMan™) _ . 6-44 . 6·45 ML65244 High Speed Dual Quad BufferlLine Driver .. 6-62 Ml&524S High Speed Octal Buffer Transceiver .. 6-66 ML65541 High Speed Octal Buffer/line Driver . 6-77 ML6599 Hot-Inserta ble Active SCSI Terminator .. 6-83 POWER MANAGEMENT AND CONTROL Selection Guide 7-' BatteryPowerSupply ICs ..J VI I I l ML4761 Adjustable Output Low Voltage Boost Regulator 7-12 ML4851 Low Current, Low Voltage Boost Regulator 7-200 ML4861 Low Voltage Boost Regulator 7·202 ML486lEVAL Low Voltage Boost Regulator Evaluation Kit 7-213 ML4862 Banery Power Controller IC............ 7-214 ML4862EVAL Battery Power Controller Evaluation Kit... 7-224 Ml4863 High Efficiency Battery Pack Converter 7-225 Ml4865 High Voltage. High Current Boo5t Regulator 7-241 ML4866 3.3V Output DC-DC Step-Down Converter 7-243 ML4868 High Frequency, Low Voltage Boost Regulator 7-244 Ml4871 High Current Boost Regulator 7·252 Ml4672 High Current Boost Regulator with Shutdown...... 7-254 ML4873 Battery Power Control Ml4873EVAL Battery Management IC Evaluation Kit 7-266 ML4875 Low Voltage Boost Regulator with Shutdown 7-277 Ie 7-256 Ml4880 Portable PC and PCMelA Power Controller 7.295 ML4890 High Efficiency, Low Ripple Boost Regulator 7-297 ML4890EV"L Low Ripple Boost Regulator Evaluation Kit 7·299 ML4961 Adjustable Output Low Voltage Boost Regulator with Detect 7-300 'Micro Unear