SC2602

SC2602 SEMTECH | Alldatasheet

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Technical content

Features

Applications

Revision: October 13, 2004 Typical Application Circuit

Description

‹ Synchronous operation for high efficiency (95%) ‹ RDS(ON) current sensing ‹ On-chip power good and OVP functions ‹ Small size with minimum external components ‹ Soft Start ‹ Enable function ‹ Microprocessor core supply ‹ Low cost synchronous applications ‹ Voltage Regulator Modules (VRM) ‹ DDR termination supplies ‹ Networking power supplies ‹ Sequenced power supplies The SC2602 and SC2602A are low-cost, full featured, synchronous voltage-mode controllers designed for use in single ended power supply applications where efficiency is of primary concern. Synchronous operation allows for the elimination of heat sinks in many applications. The SC2602s are ideal for implementing DC/DC converters needed to power advanced microprocessors in low cost systems, or in distributed power applications where effi- ciency is important. Internal level-shift, high-side drive circuitry, and preset shoot-thru control, allows the use of inexpensive N-channel power switches. SC2602s features include temperature compensated voltage reference, triangle wave oscillator and current sense comparator circuitry. Power good signaling, shut- down, and over voltage protection are also provided. The SC2602 operates at a fixed 200kHz and the SC2602A at 500kHz, providing a choice for optimum compromise between efficiency, external component size, and cost. Two SC2602s can be used together to sequence power up of telecom systems. The power good of the first SC2602 connected to the enable of the second SC2602 makes this possible. Typical Distributed Power Supply Figure 1. VCC 1 PWRGD 2 OVP 3 OCSET 4 PHASE 5 DRVH 6 PGND 7 DRVL 8 BSTL 9 BSTH 10 SENSE 11 SS/SHDN 13 GND 14 SC2602 STP40NE STP40NE 3.9 L1 2uH 180/4V C10 180/4V C11 180/4V C12 180/4V 680/6.3V 680/6.3V R1 0.1 0.1 0.1 PWRGD OVP SHDN Vin Vout=2.5V 127 124* NOTE: *) Vout = 1.265 x (1+R8/R7) +5V MBR0520 2.2 1.0 10.0 680/6.3V +12V C13 180/4V 0.1 COMP 12 4.99K 820pF

2 2004 Semtech Corp. www.semtech.com POWER MANAGEMENT SC2602/SC2602A

Electrical Characteristics

retemaraPl obmySm umixaMs tinU DNGotLTSB,CCVV NI )egruSV02(61ot0.1-V DNGotDNGP 5.0±V DNGotESAHP )1( )egruSV02(81ot5.0-V ESAHPotHTSB )egruSV02(61V esaCotnoitcnuJecnatsiseRlamrehT θ CJ 54W /C° tneibmAotnoitcnuJecnatsiseRlamrehT θ AJ 511W /C° egnaRerutarepmeTgnitarepOT A 58+ot04-C ° erutarepmeTnoitcnuJmumixaMT J 521C ° egnaRerutarepmeTegarotST GTS 051+ot56-C ° .ceS01)gniredloS(erutarepmeTdaeLT DAEL 003C ° )ledoMydoBnamuH(gnitaRDSED SE2 V k Unless specified: VCC = 4.75V to 12.6V; GND = PGND = 0V; FB = VO; VBSTL = 12V; VBSTH-PHASE = 12V; TJ = 25oC retemaraPs noitidnoCn iMp yTx aMs tinU ylppuSrewoP egatloVylppuSC CV2 .46 .21V tnerruCylppuSC CV=NE6 0 1A m noitalugeReniLV 5.2=OV5 .0% reifilpmArorrE )LOA(niaG 05B d saiBtupnI 58 A µ rotallicsO ycneuqerFrotallicsO2 062CS0 810 020 22z Hk A2062CS0 540 050 55 elcyCytuDxaMrotallicsO0 95 9% srevirDTEFSOM kniS/ecruoSHD, V5.4=HD-HTSB V2=ESAHP-HD kniS/ecruoSLD. V5.4=LD-LTSB V2=.DNGP-LD Exceeding the specifications below may result in permanent damage to the device, or device malfunction. Operation outside of th e parameters specified in the Electrical Characteristics section is not implied. Note: (1) -1.5V to 20V for 25ns repetitive every cycle.

3 2004 Semtech Corp. www.semtech.com POWER MANAGEMENT SC2602/SC2602A Electrical Characteristics (Cont.) Note: (1) Specification refers to application circuit (Figure 1). Unless specified: VCC = 4.75V to 12.6V; GND = PGND = 0V; FB = VO; VBSTL = 12V; VBSTH-PHASE = 12V; TJ = 25oC retemaraPs noitidnoCn iMp yTx aMs tinU NOITCETORP egatloVdlohserhTPVO 02% tnerruCecruoSPVOV PVO V3=0 1A m dlohserhTdooGrewoP8 82 11% emiTdaeD5 40 01s n knisIteStnerrucrevOV 0.2 ≤ V TESCO ≤ V210 810 020 22A µ ecnerefeR egatloVecnerefeRC °07otC°02 52.15 62.18 72.1V ycaruccA1 -1 +% tratStfoS tnerruCegrahCV SS V5.1=0 .80 12 1A µ tnerruCegrahcsiDV SS V5.1=5 .1A µ

4 2004 Semtech Corp. www.semtech.com POWER MANAGEMENT SC2602/SC2602A Pin Configuration Ordering Information Pin Descriptions eciveD )2()1( ycneuqerFe gakcaP TRTS2062CSz Hk0024 1-OS TRTSA2062CSz Hk005 BVE2062CSd raoBnoitaulavE Notes: (1) Only available in tape and reel packaging. A reel contains 2500 devices. (2) Lead free product. (14-Pin SOIC) Top View Note: (1) All logic level inputs and outputs are open collector TTL compatible. GND COMP SENSE BSTH BSTL DL SS / SHDN VCC OVP OCSET PHASE DH PGND PWRGD #niPe maNniPn oitcnuFniP 1C CV. egatlovylppuspihC 2D GRWP. egatlovtuptuotcerrocsetacidnihgihcigoL 3P VO. noitcetorpegatlovrevO 4T ESCO. tnioppirttnerrucrevoretrevnocehtsteS 5E SAHP. sTEFSOMehtneewtebedonesahpehtmorftupnI 6H D. tuptuorevirdedishgiH 7D NGP. dnuorgrewoP 8L D. tuptuorevirdediswoL 9L TSB. revirdediswol,partstooB 01H TSB. revirdedishgih,partstooB 11E SNES. tupniesnesegatloV 21P MOC. nipnoitasnepmoC 31N DHS/SS. emittratswolsehtstesdnuorgotroticapacA.tratstfoS 41D NG. dnuorglangiS

5 2004 Semtech Corp. www.semtech.com POWER MANAGEMENT SC2602/SC2602A Block Diagram Synchronous Buck Converter Primary V CORE power is provided by a synchronous, volt- age-mode pulse width modulated (PWM) controller. This section has all the features required to build a high effi- ciency synchronous buck converter, including “Power Good” flag, shut-down, and cycle-by-cycle current limit. The output voltage of the synchronous converter is set and controlled by the output of the error amplifier. The external resistive divider reference voltage is derived from an internal trimmed-bandgap voltage reference (See Fig. 1). The inverting input of the error amplifier receives its voltage from the SENSE pin. The internal oscillator uses an on-chip capacitor and trimmed precision current sources to set the oscillation frequency to 200kHz/500kHz. The triangular output of the oscillator sets the reference voltage at the inverting input of the comparator. The non-inverting input of the comparator receives it’s input voltage from the error am- plifier. When the oscillator output voltage drops below the error amplifier output voltage, the comparator out- put goes high. This pulls DL low, turning off the low-side FET, and DH is pulled high, turning on the high-side FET (once the cross-current control allows it). When the oscil- lator voltage rises back above the error amplifier output voltage, the comparator output goes low. This pulls DH low, turning off the high-side FET, and DL is pulled high, turning on the low-side FET (once the cross-current con- trol allows it). As SENSE increases, the output voltage of the error amplifier decreases. This causes a reduction in the on- time of the high-side MOSFET connected to DH, hence lowering the output voltage. Under Voltage Lockout The under voltage lockout circuit of the SC2602 assures that the high-side MOSFET driver outputs remain in the off state whenever the supply voltage drops below set param- eters. Lockout occurs if V CC falls below 4.1V. Normal opera- tion resumes once VCC rises above 4.2V. Over-Voltage Protection The over-voltage protection pin (OVP) is high only when the voltage at SENSE is 20% higher than the target value programmed by the external resistor divider. The OVP pin is internally connected to a PNP’s collector. Power Good The power good function is to confirm that the regulator outputs are within +/-10% of the programmed level. PWRGD remains high as long as this condition is met. PWRGD is connected to an internal open collector NPN transistor. Theory of Operation

6 2004 Semtech Corp. www.semtech.com POWER MANAGEMENT SC2602/SC2602A Soft Start Initially, SS/SHDN sources 10µA of current to charge an external capacitor. The outputs of the error amplifiers are clamped to a voltage proportional to the voltage on SS/SHDN. This limits the on-time of the high-side MOSFETs, thus leading to a controlled ramp-up of the output voltages. R DS(ON) Current Limiting The current limit threshold is set by connecting an exter- nal resistor from the V CC supply to OCSET. The voltage drop across this resistor is due to the 200µA internal sink sets the voltage at the pin. This voltage is compared to the voltage at the PHASE node. This comparison is made only when the high-side drive is high to avoid false current limit triggering due to uncontributing measure- ments from the MOSFETs off-voltage. When the voltage at PHASE is less than the voltage at OCSET, an overcurrent condition occurs and the soft start cycle is initiated. The synchronous switch turns off and SS/SHDN starts to sink 2µA. When SS/SHDN reaches 0.8V, it then starts to source 10µA and a new cycle begins. Hiccup Mode During power up, the SS/SHDN pin is internally pulled low until VCC reaches the undervoltage lockout level of 4.2V. Once V CC has reached 4.2V, the SS/SHDN pin is released and begins to source 10µA of current to the external soft-start capacitor. As the soft-start voltage rises, the output of the internal error amplifier is clamped to this voltage. When the error signal reaches the level of the internal triangular oscillator, which swings from 1V to 2V at a fixed frequency of 200kHz/500kHz, switching occurs. As the error signal crosses over the oscillator signal, the duty cycle of the PWM signal continues to in- crease until the output comes into regulation. If an over- current condition has not occurred the soft-start voltage will continue to rise and level off at about 2.2V. Applications Information (Cont.) An over-current condition occurs when the high-side drive is turned on, but the PHASE node does not reach the voltage level set at the OCSET pin. The PHASE node is sampled only once per cycle during the valley of the tri- angular oscillator. Once an over-current occurs, the high- side drive is turned off and the low-side drive turns on and the SS/SHDN pin begins to sink 2µA. The soft-start voltage will begin to decrease as the 2µA of current dis- charges the external capacitor. When the soft-start volt- age reaches 0.8V, the SS/SHDN pin will begin to source 10µA and begin to charge the external capacitor causing the soft-start voltage to rise again. Again, when the soft- start voltage reaches the level of the internal oscillator, switching will occur. If the over-current condition is no longer present, normal operation will continue. If the over-current condition is still present, the SS/SHDN pin will again begin to sink 2µA. This cycle will continue indefinitely until the over- current condition is removed. In conclusion, below is shown a typical “12V Application Circuit” which has a BSTH voltage derived by bootstrapping input voltage to the PHASE node through diode D1. This circuit is very useful in cases where only input power of 12V is available. In order to prevent substrate glitching, a small-signal di- ode should be placed in close proximity to the chip with cathode connected to PHASE and anode connected to PGND.

7 2004 Semtech Corp. www.semtech.com POWER MANAGEMENT SC2602/SC2602A Application Circuit Typical 12V Application Circuit with Bootstrapped BSTH VCC 1 PWRGD 2 OVP 3 OCSET 4 PHASE 5 DRVH 6 PGND 7 DRVL 8 BSTL 9 BSTH 10 SENSE 11 SS/SHDN 13 GND 14 SC2602 STP40NE STP40NE 3.9 MBRD1035 4uH MBRA130 1.0 C10 180/4V C11 180/4V C12 180/4V C13 180/4V 270/16V 270/16V R1 0.1 0.1 0.1 1.74k PWRGD OVP SHDN Vin 12V Vout=3.3 127 205* NOTE: *) Vout = 1.265 x (1+R9/R8) +5V MBR0520 2.2 1.0 10.0 Optional C14 180/4V 270/16V COMP 4.99K 820pF

8 2004 Semtech Corp. www.semtech.com POWER MANAGEMENT SC2602/SC2602A PIN Descriptions Typical Characteristics Output Ripple Voltage Ch1: Vo_rpl 1. VIN = 5V; V O = 3.3V; I OUT = 12A Wave forms are shown for SC2602 and are similiar for SC2602A but at higher frequency. Gate Drive Waveforms Ch1: Top FET Ch2: Bottom FET Ch1: Vo_rpl 2. V IN = 5V; VOUT = 1.3V; IOUT = 12A Ch1: Top FET Ch2: Bottom FET

9 2004 Semtech Corp. www.semtech.com POWER MANAGEMENT SC2602/SC2602A Ch1: Vo_rpl 2. VIN = 5V; VOUT = 1.3V; IOUT = 12A Ch1: Top FET Ch2: Bottom FET Typical Characteristics (Cont.)

10 2004 Semtech Corp. www.semtech.com POWER MANAGEMENT SC2602/SC2602A Typical Characteristics (Cont.) Hiccup Mode Ch1: Vin Ch2: Vss Ch3: Top Gate Ch4: Vout Vin = 5V Vout = 3.3V Vbst = 12V Ch1: Vin Ch2: Vss Ch3: Top Gate Ch4: Vout Vin = 5V Vout = 3.3V Iout = 2A Vbst = 12V Start Up Mode

11 2004 Semtech Corp. www.semtech.com POWER MANAGEMENT SC2602/SC2602A Typical Characteristics (Cont.) Math Cad Close Loop Stability Analysis Output Filter Schematic:

12 2004 Semtech Corp. www.semtech.com POWER MANAGEMENT SC2602/SC2602A Error Amplifier Schematic Typical Characteristics (Cont.)

13 2004 Semtech Corp. www.semtech.com POWER MANAGEMENT SC2602/SC2602A Typical Characteristics (Cont.)

14 2004 Semtech Corp. www.semtech.com POWER MANAGEMENT SC2602/SC2602A Typical Characteristics (Cont.)

15 2004 Semtech Corp. www.semtech.com POWER MANAGEMENT SC2602/SC2602A VCC1 PWRGD2 OVP3 OCSET4 PHASE5 DRVH6 PGND7 DRVL 8 BSTL 9 BSTH SENSE 11 COMP 12 SS/SHDN 13 GND 14 C24Q2 C16 R16 C18 L2 R19 C20 C19 C21 C17 C22 C26 C23 R10 C7C6 C2R2 PWRGD OVP SHDN Vin Vout R13R12 R14 +5V R17 R11 C14 C8R4 C25D4 Vbias R6 C11 C12 C9 C10 C27 C13 C15 R5 R7 R15 R18 C28 Evaluation Board Schematic

16 2004 Semtech Corp. www.semtech.com POWER MANAGEMENT SC2602/SC2602A Semtech Corporation Power Management Products Division

200 Flynn Road, Camarillo, CA 93012

Phone: (805)498-2111 FAX (805)498-3804 Contact Information Outline Drawing - S0-14 Land Pattern - S0-14 SEE DETAIL DETAIL AA .050 BSC .236 BSC .010 .150 .337 .154 .341 .012 - 0.25

1.27 BSC

6.00 BSC

3.90 8.65 .157 .344 3.80 8.55 .020 0.31 4.00 8.75 0.51 bxN 2X N/2 TIPS SEATING aaa C E/22X A D bbb C A-B D ccc C (.041) .004 .008 .028 .016 .007 .049 .004 .053 8° 0° 0.20 0.10 - 8° 0.40 0.17 1.25 0.10 .041 .010 .069 .065 .010 1.35 (1.04) 0.72 1.04 0.25 - 1.75 1.65 0.25 c L (L1) 01 0.25 GAGE PLANE h hPLANE N A e D C H B 3. DIMENSIONS "E1" AND "D" DO NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. -B- CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). DATUMS AND TO BE DETERMINED AT DATUM PLANE NOTES: 2. -A- -H- SIDE VIEW REFERENCE JEDEC STD MS-012, VARIATION AB.4. ccc aaa bbb N DIM D DIMENSIONS MILLIMETERS MIN e L h E b c INCHES NOMMIN A MAX MAX NOM E ZG Y P (C) X THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY. CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ARE MET. NOTES: REFERENCE IPC-SM-782A , RLP NO. 302A.2. .291 .087 .024 .118 (.205) INCHES DIMENSIONS Z P Y X DIM C G MILLIMETERS .050 (5.20) 7.40 2.20 0.60 3.00 1.27