R1223N332H-TR

12345 n OUTLINE ‘99.12.8 PWM/VFM step-down DC/DC Converter R1223N Series The R1223N Series are PWM step-down DC/DC Converter controllers with low supply current by CMOS process. Each of these ICs consists of an oscillator, a PWM control circuit, a reference voltage unit, an error amplifier, a soft-start circuit, a protection circuit, a PWM/VFM alternative circuit, a chip enable circuit, and resistors for voltage detection. A low ripple, high efficiency step-down DC/DC converter can be easily composed of this IC with only four external components, or a power-transistor, an inductor, a diode and a capacitor. With a PWM/VFM alternative circuit, when the load current is small, the operation is automatically switching into the VFM oscillator from PWM oscillator, therefore the efficiency at small load current is improved. The R1223N XXXB type, which is without a PWM/VFM alternative circuit, is also available. If the term of maximum duty cycle keeps on a certain time, the embedded protection circuit works. There are two types of protection function. One is latch-type protection circuit, and it works to latch an external Power MOSFET with keeping it disable. To release the condition of protection, after disable this IC with a chip enable circuit, enable it again, or restart this IC with power-on. The other is Reset-type protection circuit, and it works to restart the operation with soft-start and repeat this operation until maximum duty cycle condition is released. Either of these protection circuits can be designated by users’ request. n FEATURES l Range of Input Voltage · · · · · · · · · · · · ·2.3V~13.2V l Built-in Soft-start Function and Two choices of Protection Function (Latch-type or Reset type) l Two choices of Oscillator Frequency · · · · · ·300kHz, 500kHz l High Efficiency · · · · · · · · · · · · · · · · · ·TYP. 90% l Output Voltage · · · · · · · · · · · · · · · · · Stepwise Setting with a step of 0.1V in the range of 1.5V ~ 5.0V l Standby Current · · · · · · · · · · · · · · · · ·TYP. 0µA l High Accuracy Output Voltage · · · · · · · · · ·±2.0% l Low Temperature-Drift Coefficient of Output Voltage · · · · · TYP. ±100ppm/°C n APPLICATIONS l Power source for hand-held communication equipment, cameras, video instruments such as VCRs, camcorders. l Power source for battery-powered equipment. l Power source for household electrical appliances. 12345 Rev. 1.11 -1- n BLOCK DIAGRAM VIN OSC VOUT Vref EXT PWM/VFM CONTROL Protection Soft Start Chip Enable CE GND n SELECTION GUIDE In the R1223N Series, the output voltage, the oscillator frequency, the optional function, and the taping type for the ICs can be selected at the user’s request. The selection can be made by designating the part number as shown below; R1223NXXXX-XX - -- a bc Code a b c d Contents d Setting Output Voltage(VOUT): Stepwise setting with a step of 0.1V in the range of 1.5V to 5.0V is possible. Designation of Oscillator Frequency 2 : fixed Designation of Optional Function A : 300kHz, with a PWM/VFM alternative circuit, Latch-type protection B : 500 kHz, with a PWM/VFM alternative circuit, Latch-type protection C : 300kHz, without a PWM/VFM alternative circuit, Latch-type protection D : 500kHz, without a PWM/VFM alternative circuit, Latch-type protection E : 300kHz, with a PWM/VFM alternative circuit, Reset-type protection F : 500 kHz, with a PWM/VFM alternative circuit, Reset-type protection G : 300kHz, without a PWM/VFM alternative circuit, Reset-type protection H : 500kHz, without a PWM/VFM alternative circuit, Reset-type protection Designation of Taping Type; Ex. :TR,TL(refer to Taping Specification) ”TR” is prescribed as a standard. 12345 Rev. 1.11 -2- n PIN CONFIGURATION l SOT-23-5 5 VIN 4 EXT (mark side) CE GND VOUT 1 2 3 n PIN DESCRIPTION Pin No. 1 2 3 4 5 Symbol CE GND VOUT EXT VIN Chip Enable Pin Ground Pin Pin for Monitoring Output Voltage External Transistor Drive Pin Power Supply Pin Description n ABSOLUTE MAXIMUM RATINGS Symbol VIN VEXT VCE VOUT IEXT PD Topt Tstg Item VIN Supply Voltage EXT Pin Output Voltage CE Pin Input Voltage VOUT Pin Input Voltage EXT Pin Inductor Drive Output Current Power Dissipation Operating Temperature Range Storage Temperature Range Rating 15 -0.3~VIN+0.3 -0.3~VIN+0.3 -0.3~VIN+0.3 ±25 250 -40~+85 -55~+125 Unit V V V V mA mW °C °C 12345 Rev. 1.11 -3- n ELECTRICAL CHARACTERISTICS lR1223N**2A(,C,E,G) Output Voltage : Vo Symbol VIN VOUT Item Operating Input Voltage Step-down Output Voltage VIN=VCE=Vo+1.2V,IOUT=-10mA Conditions MIN. 2.3 Vo´ 0.98 DVOUT/ DT fosc DfOSC/ DT IDD1 Istb IEXTH IEXTL ICEH ICEL VCEH VCEL Maxdty VFMdty Tstart Step-down Output Voltage Temperature Coefficient Oscillator Frequency Oscillator Frequency Temperature Coefficient Supply Current1 Standby Current EXT "H" Output Current EXT "L" Output Current CE "H" Input Current CE "L" Input Current CE "H" Input Voltage CE "L" Input Voltage Oscillator Maximum Duty Cycle VFM Duty Cycle Delay Time by Soft-Start function (Topt=25°C) TYP. MAX. Unit 13.2 Vo Vo´ 1.02 ±100 ppm /°C V V -40°C £ Topt £ 85°C VIN=VCE=Vo+1.2V,IOUT=-100mA -40°C £ Topt £ 85°C 240 300 ±0.3 360 kHz % /°C VIN=13.2V,VCE=13.2V,VOUT=13.2V VIN=13.2V,VCE=0V,VOUT=0V VIN=8V,VEXT=7.9V,VOUT=8V,VCE=8V VIN=8V,VEXT=0.1V,VOUT=0V,VCE=8V VIN=13.2V,VCE=13.2V,VOUT=13.2V VIN=13.2V,VCE=0V,VOUT=13.2V VIN=8V,VOUT=0V®1.5V VIN=8V,VOUT=1.5V®0V 0.3 100 only for A, E version VIN= Vo+1.2V, VCE=0V®Vo+1.2V specified at 80% for rising edge 5 -0.5 10 100 0 -10 20 0 0 0.8 0.8 160 0.5 -6 mA mA mA mA 0.5 mA mA 1.2 V V % 25 10 16 % ms Tprot Delay Time for protection circuit VIN=VCE=Vo+1.2V VOUT= Vo+1.2V®0V 1 3 5 ms 12345 Rev. 1.11 -4- lR1223N**2B(,D,F,H) Output Voltage : Vo Symbol VIN VOUT Item Operating Input Voltage Step-down Output Voltage VIN=VCE=Vo+1.2V,IOUT=-10mA Conditions MIN. 2.3 Vo´ 0.98 DVOUT/ DT fosc DfOSC/ DT IDD1 Istb IEXTH IEXTL ICEH ICEL VCEH VCEL Maxdty VFMdty Tstart Step-down Output Voltage Temperature Coefficient Oscillator Frequency Oscillator Frequency Temperature Coefficient Supply Current1 Standby Current EXT "H" Output Current EXT "L" Output Current CE "H" Input Current CE "L" Input Current CE "H" Input Voltage CE "L" Input Voltage Oscillator Maximum Duty Cycle VFM Duty Cycle Delay Time by Soft-Start function (Topt=25°C) TYP. MAX. Unit 13.2 Vo Vo´ 1.02 ±100 ppm /°C V V -40°C £ Topt £ 85°C VIN=VCE=Vo+1.2V,IOUT=-100mA -40°C £ Topt £ 85°C 400 500 ±0.3 600 kHz % /°C VIN=13.2V,VCE=13.2V,VOUT=13.2V VIN=13.2V,VCE=0V,VOUT=0V VIN=8V,VEXT=7.9V,VOUT=8V,VCE=8V VIN=8V,VEXT=0.1V,VOUT=0V,VCE=8V VIN=13.2V,VCE=13.2V,VOUT=13.2V VIN=13.2V,VCE=0V,VOUT=13.2V VIN=8V,VOUT=0V®1.5V VIN=8V,VOUT=1.5V®0V 0.3 100 only for B, F version VIN= Vo+1.2V, VCE=0V® Vo+1.2V specified at 80% for rising edge 3 -0.5 10 140 0 -10 20 0 0 0.8 0.8 200 0.5 -6 mA mA mA mA 0.5 mA mA 1.2 V V % 25 6 10 % ms Tprot Delay Time for protection circuit VIN=VCE=Vo+1.2V VOUT= Vo+1.2V®0V 1 2 4 ms 12345 Rev. 1.11 -5- n TEST CIRCUITS A) PMOS L E) 5 4 3 5 4 3 V VIN 1 2 SD CIN VIN A 1 2 CL F) B) A 5 4 3 OSCILLOSCOPE PMOS L 5 4 3 V VIN VIN 1 2 CIN 1 2 SD CL CIN OSCILLOSCOPE C) A 5 4 3 G) OSCILLOSCOPE 5 4 3 VIN 1 2 VIN 1 2 VOUT D) 5 4 A VEXT 3 VIN VOUT 1 2 The typical characteristics were obtained by use of these test circuits. Test Circuit A : Typical characteristics 1), 2), 3), 4), 5), 6), 7) Test Circuit B : Typical characteristics 8) Test Circuit C : Standby Current Test Circuit D : Typical characteristics 12), 13) Test Circuit E : CE input current “H” and “L” Test Circuit F : Typical characteristics 9) Test Circuit G : Typical characteristics 10), 11) 12345 Rev. 1.11 -6- n TYPICAL APPLICATIONS AND APPLICATION HINTS PMOS L VIN CE CIN GND EXT VOUT SD1 COUT Load CE CONTROL PMOS : HAT1020R(Hitachi), Si3443DV(Siliconix) SD1 CIN : RB491D (Rohm) : 10mF52(Tantalum Type) L : CD105(Sumida, 27mH) COUT : 47mF(Tantalum Type) When you use these ICs, consider the following issues; l As shown in the block diagram, a parasitic diode is formed in each terminal, each of these diodes is not formed for load current, therefore do not use it in such a way. When you control the CE pin by another power supply, do not make its "H" level more than the voltage level of VIN pin. l The operation of Latch-type protection circuit is as follows; When the maximum duty cycle continues longer than the delay time for protection circuit, (Refer to the Electrical Characteristics) the protection circuit works to shut-down Power MOSFET with its latching operation. Therefore when an input/output voltage difference is small, the protection circuit may work with small load current. To release the protection latch state, after disable this IC with a chip enable circuit, enable it again, or restart this IC with power-on. However, in the case of restarting this IC with power-on, after the power supply is turned off, if a certain amount of charge remains in CIN, or some voltage is forced to VIN from CIN, this IC might not be restarted even after power-on. If rising transition speed of supply voltage is too slow, or the time which is required for VIN voltage to reach Output voltage of DC/DC converter is longer than soft-starting time plus delay time for protection circuit, protection circuit works before VIN voltage reaches Output voltage of DC/DC converter. To prevent this action, while power supply voltage is not ready, make this IC be standby mode(CE=”L”), and when the power supply is ready (the voltage level of VIN is equal or more than the voltage level of VOUT), make it enable(CE=”H”). l The operation of Reset-type protection circuit is as follows; When the maximum duty cycle continues longer than the delay time for protection circuit, (Refer to the Electrical Characteristics) the protection circuit works to restart with soft-start operation. Therefore when an input/output voltage difference is small, the protection circuit may work with small load current. l Set external components as close as possible to the IC and minimize the connection between the components and the IC. In particular, a capacitor should be connected to VOUT pin with the minimum connection. And make sufficient grounding and reinforce supplying. A large switching current flows through the connection of power supply, an inductor and the connection of VOUT. If the impedance of the connection of power supply is high, the voltage level of power supply of the IC fluctuates with the switching current. This may cause unstable operation of the IC. l Use capacitors with a capacity of 22mF or more for VOUT pin, and with good high frequency characteristics such as tantalum capacitors. We recommend you to use capacitors with an allowable voltage which is at least twice as much as setting output voltage. This is because there may be a case where a spike-shaped high voltage is generated by an inductor when an external transistor is on and off. l Choose an inductor that has sufficiently small D.C. resistance and large allowable current and is hard to reach magnetic saturation. And if the value of inductance of an inductor is extremely small, the ILX may exceed the absolute maximum rating at the maximum loading. 12345 Rev. 1.11 -7- Use an inductor with appropriate inductance. l Use a diode of a Schottky type with high switching speed, and also pay attention to its current capacity. l Do not use this IC under the condition at VIN voltage less than minimum operating voltage. P The performance of power source circuits using these ICs extremely depends upon the peripheral circuits. Pay attention in the selection of the peripheral circuits. In particular, design the peripheral circuits in a way that the values such as voltage, current, and power of each component, PCB patterns and the IC do not exceed their respected rated values. n OPERATION of step-down DC/DC converter and Output Current The step-down DC/DC converter charges energy in the inductor when Lx transistor is ON, and discharges the energy from the inductor when Lx transistor is OFF and controls with less energy loss, so that a lower output voltage than the input voltage is obtained. The operation will be explained with reference to the following diagrams : i1 IOUT L VIN Lx Tr SD i2 CL ton T=1/fosc Step 1 : LxTr turns on and current IL(=i1) flows, and energy is charged into CL. At this moment, IL increases from ILmin(=0) to reach ILmax in proportion to the on-time period(ton) of LXTr. Step 2 : When LxTr turns off, Schottky diode(SD) turns on in order that L maintains IL at ILmax, and current IL(=i2) flows. Step 3 : IL decreases gradually and reaches ILmin after a time period of topen, and SD turns off, provided that in the continuous mode, next cycle starts before IL becomes to 0 because toff time is not enough. In this case, IL value is from this ILmin(>0). In the case of PWM control system, the output voltage is maintained by controlling the on-time period(ton), with the oscillator frequency(fosc) being maintained constant. l Discontinuous Conduction Mode and Continuous Conduction Mode The maximum value(ILmax) and the minimum value(ILmin) of the current which flows through the inductor are the same as those when LxTr is ON and when it is OFF. The difference between ILmax and ILmin, which is represented by DI ; DI = ILmax – ILmin = VOUT ´ topen / L = (VIN-VOUT)´ton/L×××Equation 1 wherein T=1/fosc=ton+toff duty(%)=ton/T´100=ton´fosc´100 topen £ toff In Equation 1, VOUT´topen/L and (VIN-VOUT)´ton/L are respectively show the change of the current at ON, and the change of the current at OFF. When the output current(IOUT) is relatively small, topen0). The former mode is referred to as the discontinuous mode and the latter mode is referred to as continuous mode. In the continuous mode, when Equation 1 is solved for ton and assumed that the solution is tonc, toff VOUT ILmin topen ILmax 12345 Rev. 1.11 -8- tonc=T´VIN/VOUT××× Equation 2 When ton