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1、t 厂匚n -匚h 尸TCS4203r 4.5M 2A Synchronous StepDow n Con verierRev.1.0 May.232012 Page 3Rev.1.0 May.232012 Page 3FEATURES High Efficiency: Up to 96% 1.5MHz Constant Frequency Operation 2A Output Current No Schottky Diode Required 2.3V to 6V Input Voltage Range Output Voltage as Low as 0.6V PFM Mode for
2、 High Efficiency in Light Load 100% Duty Cycle in Dropout Operation Low Quiescent Current: 4QjA Short Circuit Protection Thermal Fault Protection Inrush Current Limit and Soft Start 1pA Shutdown Current SOT23-5 packageAPPLICATIONS Cellular and Smart Phones Wireless and DSL Modems PDAs Portable Instr
3、uments Digital Still and Video Cameras PC CardsGENERAL DESCRIPTIONThe TCS4203 is a 1.5MHz constant frequency, current mode step-down converter. It is ideal for portable equipment requiring very high current up to 2A from single-cell Lithiunrion batteries while still achieving over 90% efficiency dur
4、ing peak load condtions. The TCS4203 also can run at 100% duty cycle for low dropout operation, extending battery life in portable systems while light load operation provides very low output ripple for noise sensitive applications. The TCS4203 can supply up to 2A output load current from a 2.3V to 6
5、V input voltage and the output voltage can be regulated as low as 0.6V. The high switching frequency minimizes the size of external components while keeping switching losses low. The internal slope compensation setting allows the device to operate with smaller in ductor values to optimize size and p
6、rovide efficient operation. The TCS4203 is offered in a low profile (1mm) 6-pin, thin SOT package, end is available in an adjustable version.This device offers two operation modes, PWM control and PFM Mode switching control, which allows a high efficiency over the wider range of the load.Rev.1.0 May
7、.232012 Page 3TYPICAL APPLICATIONFigure 1. Basic Application CircuitRev.1.0 May.232012 Page 3T 口厂匚n -匚h 尸1.5MHz, 2A Synchronous Step-Down ConverterABSOLUTE MAXIMUM RATINGS (Note 1)Rev.1.0 May.232012 Page 3Rev.1.0 May.232012 Page 3Input Supply Voltage-0.3V to 6.5VEN,FB Voltages.-0.3 to (Vin+0.3V)LX V
8、oltage -0.3Vto (Vin+0.3V)Operating Temperature Range . -40C to +85CLead Temperature(Soldering.10s)+300CStorage Temperature Range r65C to 150CRev.1.0 May.232012 Page 3PIN CONFIGURATIONEN16GND25LX34FBNCVINSOT23 百TCS4203PIN DESCRIPTIONNAMEPINFUNCTIONEN1Chip Enable Pin. Drive CN above 1.5V to turn on th
9、e part. Drive 匚N below 0.3/ to turn it off. Do not leaveEN floating.GND2Analog ground pn.LX3Power Switch Output. It is the switch node conn ectio n to In ductor. This pin cormects to the drains of the internal Rch and N-ch MOSFET switches.MN4An alog supply in put pin.NC5No ConnectFB6Output Voltage F
10、eedback Pin. An internal resistive divider divides the output voltage down for comparison to the internal referenee voltageRev.1.0 May.232012 Page 3t r匚n -匚n 尸TCS4203r 4.5MH 乙 2A Synchronous StepDow n Con verierELECTRICAL CHARACTERISTICS (Note 3)(V|N=VEN=3.6V1 VOut=1.8V? Ta = 25C, unless otherwise n
11、oted )ParameterConditionsMINTYPMAXunitInput Voyage Range2.36VUVLO Threshold1.71.92.1VInput DC Supply CurrentPWM ModePFM ModeShutdown Mode(Note 4)Vout = 90%: lload=0mAVout = 105%, lload=0mAVen = 0V, ViN=4.2V150400 1300751.0ma ma ma maRegulated FeedbackVoltage VFBTa = 25C0.5880.6000.612VTa = 0C s Ta S
12、8590.5860.6000.613V匚二40C Ta g 1.5000ui 1.4001.3000.59Vjn=3.6V,Vout=1.8V0.610605OGC.5$54C.0 -200 00 20.0 40 0 60.D 80.0 1CO.O 1200TeTrp erat.reC)1.20048 32 16016 32 48648096lEMPERATUREfC)VOUT伽7DTLXIL5mA/Dr/ouMtViOOre/dVRev.1.0 May.232012TCS4203PFM MODE“Rev.1.0 May.232012TCS4203t 口厂匚n -匚n 尸1.5MHz, 2A
13、Synchronous Step-Down ConverterPWM MODEpStart-UpRev.1.0 May.232012 Page 2TCS4203Rev.1.0 May.232012 Page 2TCS4203FUNCTIONAL BLOCK DIAGRAMRev.1.0 May.232012 Page 2TCS4203Rev.1.0 May.232012 Page 2TCS4203ENVDDGNDFigure2. TCS4203 Block DiagramRev.1.0 May.232012 Page 2t 厂匚n -匚h 尸TCS4203r 4.5MH 乙 2A Synchr
14、onous StepDow n Con verierFUNCTIONAL DESCRIPTIONRev.1.0 May.232012 Page 3The TCS4203 is a high output current monolithic switch mode step-down DC-DC converter. The device operates at a fixed 1.5MHz switching frequency. and uses a slope compensated current mode architecture. This step-down DC-DC conv
15、erter can supply up to 2A output current at VIN = 3.6V and has an in put voltage range from 2.3 V to 6V. It minimizes external component size and optimizes efficiency at the heavy load ange. The slope compensation allows the device to remain stable over a wider range of inductor values so that small
16、er values (1pH to 4.7pH) with lower DCR can be used to achieve higher efficiency. Only a small bypass input capacitor is required at the output. The adjustable output voltage can be programmed with external feedback to any voltage, ranging from 0.6V to near the in put voltage .It uses internal MOSFE
17、Ts to achieve high efficiency and can gen erate very low output voltages by using an internal reference of 0.6V. At dropout operation, the converter duty cycle in creases to100% and the output voltage tracks the input voltage minus the low RDS(ON) drop of the P-channel high-side MOSFET and the induc
18、tor DCR The internal error amplifier and compensation provides excellent transient response? load and line regulation .In tern al soft start eliminates any output voltage overshoot when the en able or the in put voltage is applied.Setting the Output VoltageFigure 1 shows the basic application circui
19、t for the TCS4203. The TCS4203 can be externally programmed Resistors R1 and R2 in Figure 1 program the output to regulate at a voltage higher than 0.6V. To limit the bias current required for the external feedback resistor string while maintaining good noise immunity, the minimum suggested value fo
20、r R2 is 59kQ. Although a larger value wll further reduce quiesce nt curre nt, it will also in crease the impedance of the feedback node： making it more sensitive to external noise and interference. Table 1 summarizes the resistor values for various output voltages with R2 set to either 59kQ for good
21、 noise imminity or 316kQ for reduced no load input current. The external resistor sets the output voltage according to the following equatiorr/out = 66 x Q +1)尺)艮=(如/0.6_l)x&Table 1 shows the resistor selection for different output voltage settings.Vout (V)R2 a 59k2 R1 (kn)R2 = 316k2 R1(kQ)0.819.610
22、50.929.41581.039.22101.149.92611.259.03161.363.13651.478.74221.583.74751.81186341.851246552.01377322.518710003.32671430Rev.1.0 May.232012 Page 3Table 1: Resistor selections for different output voltage settings (standard 1% resistors substituted for calculated values).Rev.1.0 May.232012 Page 3TCS420
23、3t r匚n -匚h 尸1.5MHz, 2A Synchronous Step-Down ConverterAPPLICATIONS INFORMATIONRev.1.0 May.232012 Page 2TCS4203Inductor SelectionFor most designs, the TCS4203 operates with inductors of 1pH to 4.7pH. Low inductance values are physically smaller but require faster switching, which results in some effi
24、ciency loss. The inductor value can be derived from the following equation:勺 x Z l x foscWhere Al L is inductor Ripple Current. Largevalue in ductors result in lower ripple curre nt and small value in ductors result in high ripple curre nt. For optimum voltage-positioning load transients, choose an
25、in ductor with DC series resistance inIn put Capacitor Selecti onThe in put capacitor reduces the surge current drawn from the input and switching noise from the device. The input capacitor impedance at the switching frequency should be less th an input source impedanee to prevent high frequency swi
26、tching current passing to the input. A low ESR input capacitor sized for maximum RMS current must be used. Ceramic capacitors with X5R or X7R dielectrics are highly recommended because of their low ESR and small temperature coefficients. A 22pF ceramic capacitor for most applications is sufficient.
27、A large value may be used for improved input voltage filtering.Rev.1.0 May.232012 Page 2TCS4203Manu factu rerPartNumberInd(uH)DCR(OhMaxDC Curren t(A)SizeUVTH(mm3)SumidaCDRH5D162.228.735.8x58x1.83.335.62.647193 48.3x8.3x3.0SumidaCDRH5D162.2233.33.3292.65.2x52x3.04.7392.1the 50mQ to 150mQ rangeTable2.
28、Recommend Surface Mount In ductorsA rr v OUTovr)心F仏xLx ESR +Output Capacitor SelectionThe output capacitor is required to keep the output voltage ripple small and to ensure regulation loop stability. The output capacitor must have low impedanee at the switching frequency. Ceramic capacitors with X5R
29、 or X7R dielectrics are recommended due to their low ESR and high ripple current ratings. The output ripple AV0Ut is determined by:A 22jjF ceramic can satisfy most applications.Rev.1.0 May.232012 Page 2TCS4203T 口厂匚n-匚h 尸1.5MHz, 2A Synchronous Step-Down ConverterRev.1.0 May.232012 Page 2TCS4203Rev.1.
30、0 May.232012 Page 2TCS4203PCB Layout RecommendationsWhen laying out the pnnted circuit board, the following checking should be used to ensure proper operation of the TCS4203. Check the following in your layout:1. The power traces, consisting of the GND trace, the LX trace and the VIN trace should be
31、 kept short, direct and wide2. Does the (+) plates of Cin connect to Vin as closely as possible. This capacitor provides the AC current to the internal power MOSFETs.3. Keep the switchi ng no de, LX, away from the sensitive VOUT node.Keep the (-) plates of Cin and Cout as close as possibleRev.1.0 Ma
32、y.232012 Page 2T 厂匚n-匚h匚尸PACKAGE DESCRIPTIONTCS42031.5MHz, 2A Synchronous Step-Down Con verierRev.1.0 May.232012 Page 3Rev.1.0 May.232012 Page 3Sen Noto T EXAMPLE TOP MARKPIN 1TOP VIEWRECOMMENDED LAND PATTERN1.45 MAXSEATING PLANESIDEVIEWDETAILRev.1.0 May.232012 Page 3Rev.1.0 May.232012 Page 3Figure BDirnensiawRev.1.0 May.232012 Page 3