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R1234D SERIES
PWM/VFM Step-Down DC/DC CONVERTER with Synchronous Rectifier
NO.EA-137-070221
OUTLINE
The R1234D Series are CMOS-based PWM step-down DC/DC Converters with synchronous rectifier, low supply current. Each of these ICs consists of an oscillator, a PWM control circuit, a reference voltage unit, an error amplifier, a soft-start circuit, protection circuits, a protection against miss operation under low voltage (UVLO), PWM/VFM alternative circuit, a chip enable circuit, and a driver transistor. A low ripple, high efficiency step-down DC/DC converter can be easily composed of this IC with only a few kinds of external components, or an inductor and capacitors. (As for R1234D001C/D types, divider resistors are also necessary.) In terms of Output Voltage, it is fixed internally in the R1234Dxx1A/B types. While in the R1234D001C/D types, Output Voltage is adjustable with external divider resistors. PWM/VFM alternative circuit is active with Mode Pin of the R1234D Series. Thus, when the load current is small, the operation can be switching into the VFM operation from PWM operation by the logic of MODE pin and the efficiency at small load current can be improved. As protection circuits, Current Limit circuit which limits peak current of Lx at each clock cycle, and Latch type protection circuit which works if the term of Over-current condition keeps on a certain time in PWM mode exist. Latch-type protection circuit works to latch an internal driver 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 or make the supply voltage at UVLO detector threshold level or lower than UVLO.
FEATURES
* Supply Current ..................................................Typ. 230A (R1234Dxx1A/C) Typ. 250A (R1234Dxx1B/D) * Standby Current ................................................Typ. 0A * Input Voltage Range ........................................ 2.4V to 5.5V (ABSOLUTE MAXIMUM : 6.5V) * Output Voltage Range.......................................2.2V to 3.3V (R1234Dxx1A/B) 0.8V to VIN (R1234Dxx1C/D) * Output Voltage Accuracy...................................2.0% (R1234DxxA/B) * Oscillator Frequency .........................................Typ. 500kHz (R1234Dxx1A/C) Typ. 800kHz (R1234Dxx1B/D) * Built-in Driver ON Resistance ...........................Pch 0.4 ,Nch 0.6 (VIN=3V) * Control mode switch .........................................MODE pin="L": PWN MODE pin="H": VFM * Efficiency...........................................................Typ. 90% * Package ............................................................SON-8 * Built-in Soft-start Function.................................Typ. 1.5ms * Latch-type Protection Function .........................Typ. 1.5ms * Built-in Current Limit Circuit
APPLICATIONS
* Power source for portable equipment.
1
R1234D
BLOCK DIAGRAM
R1234Dxx1A/B
VDD MODE
"L" PWM "H" VFM
3
VIN
6
1
OSC PWM/VFM CONTROL Phase Comp.
5
VOUT
Lx
8
OUTPUT CONTROL
Vref
CE UVLO "H" Active Soft Start Chip Enable
Current Protection
4
CE
2
PGND
7
AGND
R1234Dxx1C/D
VDD MODE
3
VIN
6
"L" PWM
"H" VFM
1
OSC PWM/VFM CONTROL Phase Comp.
5
VFB
Lx
8
OUTPUT CONTROL
Vref
Chip Enable
"H" Active
Current Limit
4
CE
UVLO Soft Start
2
PGND
7
AGND
2
R1234D
SELECTION GUIDE
In the R1234D Series, the output voltage, the oscillator frequency, and the taping type for the ICs can be selected at the user's request. The selection can be made with designating the part number as shown below;
R1234Dxx1x-xx-x Part Number
a b cd e f Code a b c Contents Designation of Package Type; D: SON-8 Setting Output Voltage (VOUT): Stepwise setting with a step of 0.1V in the range of 1.2V to 3.3V is possible for A/B version."00" is for Output Voltage Adjustable C/D version (0.8V to ) 1: fixed Designation of Optional Function A: 500kHz, Fixed Output Voltage B: 800kHz, Fixed Output Voltage C: 500kHz, Adjustable Output Voltage D: 800kHz, Adjustable Output Voltage Designation of Taping Type; (Refer to Taping Specification)"TR" is prescribed as a standard. Designation of Composition of pin plating -F: Lead free plating
d
e f
3
R1234D
PIN CONFIGURATIO
*
Top View
8 7 65
SON-8
Bottom View
56 7 8
1
2
34
43
2
1
PIN DESCRIPTION
Pin No 1 2 3 4 5 6 7 8 Symbol VIN PGND VDD CE VOUT/VFB MODE AGND LX Voltage Supply Pin Power Ground Pin Voltage Supply Pin Chip Enable Pin (active with "H") Output/Feedback Pin Mode changer Pin ("L"=PWM, "H"=VFM) Analogue Ground Pin LX Pin (CMOS) Pin Description
* Tab in the parts have GND level. (They are connected to the reverse side of this IC.) Do not connect to other wires or land patterns.
ABSOLUTE MAXIMUM RATINGS
Symbol VIN VDD VLX VCE VMODE VFB ILX PD Topt Tstg VIN Supply Voltage VDD Pin Voltage LX Pin Voltage CE Pin Input Voltage MODE Pin Input Voltage VFB Pin Input Voltage LX Pin Output Current Power Dissipation (SON-8) Operating Temperature Range Storage Temperature Range Item Rating 6.5 6.5 -0.3 to VIN +0.3 -0.3 to VIN +0.3 -0.3 to VIN +0.3 -0.3 to VIN +0.3 -0.8 480 -40 to +85 -55 to +125 Unit V V V V V V A mW C C
* ) For Power Dissipation, please refer to PACKAGE INFORMATION to be described.
4
R1234D
ELECTRICAL CHARACTERISTICS
*
R1234DxxxA
Topt=25C
Symbol VIN
Item Operating Input Voltage Step-down Output Voltage Step-down Output Voltage Temperature Coefficient Oscillator Frequency Supply Current Standby Current ON Resistance of Pch Transistor ON Resistance of Nch Transistor LX Leakage Current VOUT Leakage Current CE Input Current MODE Pin Input Current CE "H" Input Voltage CE "L" Input Voltage MODE "H" Input Voltage MODE "L" Input Voltage Oscillator Maximum Duty Cycle Delay Time by Soft-Start function LX Limit Voltage Delay Time for protection circuit UVLO Threshold Voltage UVLO Released Voltage VFM Duty Cycle
Conditions VIN=VCE=VSET+1.5V, VMODE=0V, IOUT=10mA -40C
< =
Min. 2.4
Typ.
Max. 5.5 Typ.
Unit V
VOUT
VOUT/Topt fosc IDD Istandby RONP RONN ILXleak IVOUTleak ICE IMODE VCEH VCEL VMODEH VMODEL Maxduty tstart VLXlim Tprot VUVLO1 VUVLO2 VFMduty
Typ. x0.98
VSET
150
x1.02
V
ppm/ C
Topt
< =
85C 425
VIN=VCE=VSET+1.5V VIN=VCE=VSET+1.5V, VOUT=VMODE=0V VIN=5.5V, VCE=VOUT=0V VIN=5.0V VIN=5.0V VIN=5.5V, VCE=0V, VLX=0V or 5.5V VIN=5.5V, VCE=0V, VLX=0V or 5.5V VIN=5.5V, VMODE=0V, VCE=5.5V or 0V VIN=5.5V, VCE=0V, VMODE=5.5V or 0V VIN=5.5V, VOUT=0V VIN=2.4V, VOUT=0V VIN=VCE=5.5V, VOUT=0V VIN=VCE=2.4V, VOUT=0V VMODE=0V at no load, VIN=VCE=VSET+1.5V VMODE=VOUT=0V, VIN=VCE=3.0V VIN=VCE=VSET+1.5V, VMODE=0V VIN=VCE=2.5V1.5V, VOUT =0V VIN=VCE=1.5V2.5V, VOUT=0V VIN=VCE=VMODE=2.4V, VOUT=0V
500 230 0
575 300 5 0.9 0.9 5.0 0.1 0.1 0.1
kHz A A A A A A V
0.2 0.2 -5.0 -0.1 -0.1 -0.1 1.5
0.4 0.6 0.0 0.0 0.0
0.3 1.5 0.3 100 0.5 VIN -0.15 0.5 1.8 1.9 55 1.5 VIN -0.35 1.5 2.1 2.2 65 2.5 VIN -0.65 2.5 2.2 2.3 85
V V V % ms V ms V V %
5
R1234D
*
R1234DxxxB
Topt=25C
Symbol VIN
Item Operating Input Voltage Step-down Output Voltage Step-down Output Voltage Temperature Coefficient Oscillator Frequency Supply Current Standby Current ON Resistance of Pch Transistor ON Resistance of Nch Transistor LX Leakage Current VOUT Leakage Current CE Input Current MODE Pin Input Current CE "H" Input Voltage CE "L" Input Voltage MODE "H" Input Voltage MODE "L" Input Voltage Oscillator Maximum Duty Cycle Delay Time by Soft-Start function LX Limit Voltage Delay Time for protection circuit UVLO Threshold Voltage UVLO Released Voltage VFM Duty Cycle
Conditions VIN=VCE=VSET+1.5V, VMODE=0V, IOUT=10mA -40C
< =
Min. 2.4
Typ.
Max. 5.5 Typ.
Unit V
VOUT
VOUT/Topt fosc IDD Istandby RONP RONN ILXleak IVOUTleak ICE IMODE VCEH VCEL VMODEH VMODEL Maxduty tstart VLXlim Tprot VUVLO1 VUVLO2 VFMduty
Typ. x0.98
VSET
150
x1.02
V
ppm/ C
Topt
< =
85C 680
VIN=VCE=VSET+1.5V VIN=VCE=VSET+1.5V, VOUT=VMODE=0V VIN=5.5V, VCE=VOUT=0V VIN=5.0V VIN=5.0V VIN=5.5V, VCE=0V, VLX=0V or 5.5V VIN=5.5V, VCE=0V, VLX =0V or 5.5V VIN=5.5V, VMODE=0V, VCE=5.5V or 0V VIN=5.5V, VCE=0V, VMODE=5.5V or 0V VIN=5.5V, VOUT=0V VIN=2.4V, VOUT=0V VIN=VCE=5.5V, VOUT=0V VIN=VCE=2.4V, VOUT=0V VMODE=0V at no load, VIN=VCE=VSET+1.5V VMODE=VOUT=0V, VIN=VCE=3.0V VIN=VCE=VSET+1.5V, VMODE=0V VIN=VCE=2.5V1.5V, VOUT =0V VIN=VCE=1.5V2.5V, VOUT=0V VIN=VCE=VMODE=2.4V, VOUT=0V
800 250 0
920 450 5 0.9 0.9 5.0 0.1 0.1 0.1
kHz A A A A A A V
0.2 0.2 -5.0 -0.1 -0.1 -0.1 1.5
0.4 0.6 0.0 0.0 0.0
0.3 1.5 0.3 100 0.5 VIN -0.15 0.5 1.8 1.9 55 1.5 VIN -0.35 1.5 2.1 2.2 65 2.5 VIN -0.65 2.5 2.2 2.3 85
V V V % ms V ms V V %
6
R1234D
*
R1234DxxxC
Topt=25C
Symbol VIN
Item Operating Input Voltage Feedback Voltage Feedback Voltage Temperature Coefficient Oscillator Frequency Supply Current Standby Current ON Resistance of Pch Transistor ON Resistance of Nch Transistor LX Leakage Current VFB Leakage Current CE Input Current MODE Pin Input Current CE "H" Input Voltage CE "L" Input Voltage MODE "H" Input Voltage MODE "L" Input Voltage Oscillator Maximum Duty Cycle LX Limit Voltage Delay Time by Soft-Start function Delay Time for protection circuit UVLO Threshold Voltage UVLO Released Voltage VFM Duty Cycle
Conditions VIN=VCE=VSET+1.5V, VMODE=0V, IOUT=10mA -40C
< =
Min. 2.7 0.776
Typ.
Max. 5.5
Unit V
VFB
VFB/Topt fosc IDD Istandby RONP RONN ILXleak IVFBleak ICE IMODE VCEH VCEL VMODEH VMODEL Maxduty tstart VLXlim Tprot VUVLO1 VUVLO2 VFMduty
0.800 300
0.824
V
ppm/ C
Topt
< =
85C 425
VIN=VCE=VSET+1.5V VIN=VCE=VSET+1.5V, VFB =VMODE=0V VIN=5.5V, VCE=VFB=0V VIN=5.0V VIN=5.0V VIN=5.5V, VCE=0V, VLX=0V or 5.5V VIN=5.5V, VCE=0V, VFB=0V or 5.5V VIN=5.5V, VMODE=0V, VCE=5.5V or 0V VIN=5.5V, VCE=0V, VMODE=5.5V or 0V VIN=5.5V, VFB=0V VIN=2.4V, VFB=0V VIN=VCE=5.5V, VFB=0V VIN=VCE=2.4V, VFB=0V VMODE=0V at no load, VIN=VCE=VSET+1.5V VMODE=VFB=0V, VIN=VCE=3.0V VIN=VCE=3.6V, VMODE=0V VIN=VCE=2.5V1.5V, VMODE=0V VIN=VCE=1.5V2.7V, VFB=0V VIN=VCE=VMODE=2.4V, VFB=0V
500 230 0
575 300 5 0.9 0.9 5.0 0.1 0.1 0.1
kHz A A A A A A V
0.2 0.2 -5.0 -0.1 -0.1 -0.1 1.5
0.4 0.6 0.0 0.0 0.0
0.3 1.5 0.3 100 0.5 VIN -0.15 0.5 1.95 2.20 55 1.5 VIN -0.35 1.5 2.20 2.40 65 2.5 VIN -0.65 2.5 2.45 2.65 85
V V V % ms V ms V V %
7
R1234D
*
R1234DxxxD
Topt=25C
Symbol VIN
Item Operating Input Voltage Feedback Voltage Feedback Voltage Temperature Coefficient Oscillator Frequency Supply Current Standby Current ON Resistance of Pch Transistor ON Resistance of Nch Transistor LX Leakage Current VFB Leakage Current CE Input Current MODE Pin Input Current CE "H" Input Voltage CE "L" Input Voltage MODE "H" Input Voltage MODE "L" Input Voltage Oscillator Maximum Duty Cycle LX Limit Voltage Delay Time by Soft-Start function Delay Time for protection circuit UVLO Threshold Voltage UVLO Released Voltage VFM Duty Cycle
Conditions VIN=VCE=VSET+1.5V, VMODE=0V, IOUT=10mA -40C
< =
Min. 2.7 0.776
Typ.
Max. 5.5
Unit V
VFB
VFB/Topt fosc IDD Istandby RONP RONN ILXleak IVFBleak ICE IMODE VCEH VCEL VMODEH VMODEL Maxduty tstart VLXlim Tprot VUVLO1 VUVLO2 VFMduty
0.800 300
0.824
V
ppm/ C
Topt
< =
85C 680
VIN=VCE=VSET+1.5V VIN=VCE=VSET+1.5V, VFB=VMODE=0V VIN=5.5V, VCE=VFB=0V VIN=5.0V VIN=5.0V VIN=5.5V, VCE=0V, VLX=0V or 5.5V VIN=5.5V, VCE=0V, VFB=0V or 5.5V VIN=5.5V, VMODE=0V, VCE=5.5V or 0V VIN=5.5V, VCE=0V, VMODE=5.5V or 0V VIN=5.5V, VFB=0V VIN=2.4V, VFB=0V VIN=VCE=5.5V, VFB=0V VIN=VCE=2.4V, VFB=0V VMODE=0V at no load, VIN=VCE=VSET+1.5V VMODE=VFB=0V, VIN=VCE=3.0V VIN=VCE=3.6V, VMODE=0V VIN=VCE=2.5V1.5V, VMODE=0V VIN=VCE=1.5V2.7V, VFB=0V VIN=VCE=VMODE=2.4V, VFB=0V
800 250 0
920 400 5 0.9 0.9 5.0 0.1 0.1 0.1
kHz A A A A A A V
0.2 0.2 -5.0 -0.1 -0.1 -0.1 1.5
0.4 0.6 0.0 0.0 0.0
0.3 1.5 0.3 100 0.5 VIN -0.15 0.5 1.95 2.20 55 1.5 VIN -0.35 1.5 2.20 2.40 65 2.5 VIN -0.65 2.5 2.45 2.65 85
V V V % ms V ms V V %
8
R1234D
TEST CIRCUITS
1 3 7 2
VIN Lx R1234D Series VDD CE VOUT
8 4 5 6
A
1 3 7 2
VIN
Lx R1234D Series VDD CE VOUT
8
OSCILLOSCOPE
4 5 6
AGND
AGND
PGND MODE
PGND MODE
Test Circuit for Input Current and Leakage Current
Test Circuit for Input Voltage and UVLO voltage
OSCILLOSCOPE
1 3 7 2
VIN
R1234D Series VDD CE AGND VOUT
Lx
8 4 5 6
VOUT L 10F
PGND MODE
Test Circuit for Output Voltage, Oscillator Frequency, Soft-Starting Time
OSCILLOSCOPE
1
A
VIN VDD R1234D Series
Lx CE
8 4 5 6
1 3 7 2
VIN VDD R1234D Series
Lx CE
8 4 5 6
A
3 7 2
AGND
VOUT
AGND
VOUT
PGND MODE
PGND MODE
Test Circuit for Supply Current and Standby Current
Test Circuit for ON resistance of LX, Limit Voltage, Delay Time of Protection Circuit
The bypass capacitor between power supply and GND is a ceramic capacitor 10F.
9
R1234D
TYPICAL APPLICATION AND TECHNICAL NOTES
1) Fixed Output Voltage Type
L VOUT
CIN
1 2 3 4
VIN PGND
Lx AGND
8 7 6 5
LOAD COUT
VDD CE
MODE VOUT
CIN COUT L
10F C3216JB0J106M (TDK) 10F ECSTOJX106R (Panasonic) 10H LQH3C100K54 (Murata)
2) Adjustable Output Voltage Type
L
1
CIN
VIN
Lx
8 7 6 5
Rb Cb
VOUT
2 3 4
PGND VDD CE
AGND MODE VOUT
LOAD COUT R1 R2
CIN COUT L
10F C3216JB0J106M (TDK) 10F ECSTOJX106R (Panasonic) 10H LQH3C100K54 (Murata)
VFM mode may work with a parasitic diode, but we recommend that VFM mode used with an external diode in between LX and GND. As for PWM mode, an external diode is not necessary. As for how to choose Cb, Rb, R1, and R2 values, refer to the technical notes.
10
R1234D
When you use these ICs, consider the following issues; * Input same voltage into the power supply pins, VIN and VDD. Set the same level as AGND and PGND. * When you control the CE pin and MODE pin by another power supply, do not make its "H" level more than the voltage level of VIN/VDD pin. * Set external components such as an inductor, CIN, COUT as close as possible to the IC, in particular, minimize the wiring to VIN pin and PGND pin. * At stand by mode, (CE="L"), the LX output is Hi-Z, or both P-channel transistor and N-channel transistor of LX pin turn off. * Use an external capacitor COUT with a capacity of 10F or more, and with good high frequency characteristics such as tantalum capacitors. * At VFM mode, (MODE="H"), Latch protection circuit does not operate. * If the mode is switched over into PWM mode from VFM mode during the operation, change the mode at light load current. If the load current us large, output voltage may decline. * Reinforce the VIN, PGND, and VOUT lines sufficiently. Large switching current may flow in these lines. If the impedance of VIN and PGND lines is too large, the internal voltage level in this IC may shift caused by the switching current, and the operation might be unstable. 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.
11
R1234D
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:
IL ILmax ILmin topen
i1 VIN Pch Tr Nch Tr L i2 CL GND VOUT
ton T=1/fosc
toff
Step 1: P-channel Tr. turns on and current IL (=i1) flows, and energy is charged into CL. At this moment, IL Step 2: When P-channel Tr. turns off, Synchronous rectifier N-channel Tr. turns on in order that L maintains IL Step 3: IL (=i2) decreases gradually and reaches IL=ILmin=0 after a time period of topen, and N-channel Tr.
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 increases 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. at ILmax, and current IL (=i2) flows. increases from Ilmin (=0) to reach ILmax in proportion to the on-time period (ton) of P-channel Tr.
*
Discontinuous Conduction Mode and Continuous Conduction Mode
The maximum value (ILmax) and the minimum value (ILmin) of the current flowing through the inductor are the same as those when P-channel Tr. turns on and off. The difference between ILmax and ILmin, which is represented by I; I=ILmax-ILmin=VOUTxtopen/L=(VIN-VOUT)xton/L ........................................................Equation 1 Where, t=1/fosc=ton+toff duty (%)=ton/tx100=tonxfoscx100 topen < toff = In Equation 1, VOUTxtopen/L and (VIN-VOUT) xton/L are respectively shown the change of the current at ON, and the change of the current at OFF. When the output current (IOUT) is relatively small, topen < toff as illustrated in the above diagram. In this case, the energy is charged in the inductor during the time period of ton and is discharged in its entirely during the time period of toff, therefore ILmin becomes to zero (ILmin=0). When IOUT is gradually increased, eventually, topen becomes to toff (topen=toff), and when IOUT is further increased, ILmin becomes larger than zero (ILmin>0). The former mode is referred to as the discontinuous mode and the latter mode is referred to as continuous mode.
12
R1234D
In the continuous mode, when Equation 1 is solved for ton and assumed that the solution is tonc tonc=txVOUT/VIN............................................................................................................. Equation 2 When tonOUTPUT CURRENT AND SELECTION OF EXTERNAL COMPONENTS
When P-channel Tr. of LX is ON: (Wherein, Ripple Current P-P value is described as IRP, ON resistance of P-channel Tr. and N-channel Tr. of LX are respectively described as RONP and RONN, and the DC resistor of the inductor is described as RL.) VIN=VOUT+(RONP+RL)xIOUT+LxIRP/ton .............................................................................. Equation 3 When P-channel Tr. of LX is "OFF"(N-channel Tr. is "ON"): LxIRP/toff=VF+VOUT+RONNxIOUT ....................................................................................... Equation 4 Put Equation 4 to Equation 3 and solve for ON duty of P-channel transistor, Don=ton/(toff+ton), DON=(VOUT-RONNxIOUT+RLxIOUT)/(VIN+RONNxIOUT-RONPxIOUT) ........................................... Equation 5 Ripple Current is as follows; IRP=(VIN-VOUT-RONPxIOUT-RLxIOUT)xDON/fosc/L .............................................................. Equation 6 wherein, peak current that flows through L, and LX Tr. is as follows; ILmax=IOUT+IRP/2 .......................................................................................................... Equation 7 Consider ILmax, condition of input and output and select external components. The above explanation is directed to the calculation in an ideal case in continuous mode.
13
R1234D
How to Adjust Output Voltage and about Phase Compensation
As for Adjustable Output type, feedback pin (VFB) voltage is controlled to maintain 0.8V. Output Voltage, VOUT is as following equation; VOUT R1+R2=VFB:R2 VOUT=VFBx(R1+R2)/R2 Thus, with changing the value of R1 and R2, output voltage can be set in the specified range. In the DC/DC converter, with the load current and external components such as L and C, phase might be behind 180 degree. In this case, the phase margin of the system will be less and stability will be worse. To prevent this, phase margin should be secured with proceeding the phase. A pole is formed with external components L and COUT.
fpole ~ 1/2 LCOUT
A zero (signal back to zero) is formed with R1 and Cb. fzero ~ 1/(2 xR1xCb) First, choose the appropriate value of R1, R2 and Cb. Set R1+R2 value 100k or less. For example, if L=10H, COUT=10F, the cut off frequency of the pole is approximately 16kHz. To make the cut off frequency of the zero higher than 16kHz, set R1=42k and Cb=100pF. If VOUT is set at 1.5V, R2=48k is appropriate. If a ceramic capacitor is desirable as COUT in your application, nonetheless of the usage of both the fixed output voltage type and adjustable output type, add 0.2 or more resistance to compensate the ESR. Further, if a ceramic capacitor is desirable to use as COUT without adding another resister to compensate the ESR, phase should be back drastically. To make it, R2 value should be smaller compared to R1. As a result, the set output voltage may be large. For example, to make VOUT=1.5V, constants are R1=42k, R2=48k, and Cb=100pF. If the ceramic capacitor is used, under the heavy load condition, oscillation may be result. On the other hand, if R2 = 12k and VOUT=3.6V, phase back becomes also large, and even if the device is used with a heavy load, the operation will be stable. Rb is effective for reducing the noise on VFB. However, it is not always necessary. If it is necessary, use a resistance as much as 30k as Rb.
14
R1234D
External Components
1.Inductor
Select an inductor that peak current does not exceed ILmax. If larger current than allowable current flows, magnetic saturation occurs and makes transform efficiency be worse. Supposed that the load current is at the same, the smaller value of L is used, the larger the ripple current is. Provided that the allowable current is large in that case and DC current is small, therefore, for large output current, efficiency is better than using an inductor with a large value of L and vice versa.
2.Capacitor
As for CIN, use a capacitor with low ESR (Equivalent Series Resistance) Ceramic type of a capacity at least 10F for stable operation. COUT can reduce ripple of Output Voltage, therefore as much as 10F ceramic type is recommended.
3.Diode
If VFM mode is chosen at light load, use a Schottky diode with small VF. A diode with small VF makes the efficiency of the circuit improved. Small reverse direction current, IR is an important factor, however, VF has more important priority than IR.
TIMING CHART
CE pin Voltage Intemal Opertional Amplifier Output Intemal Soft-start Set Voltage Output Short
Output Short
Intemal Oscillator Waveform Lx Pin Output
Soft-start Time
Stable
Delay Time of Protection
The timing chart as shown above describes the waveforms starting from the IC is enabled with CE and latched with protection. During the soft-start time, until the level is rising up to the internal soft-start set voltage, the duty cycle of LX is gradually wider and wider to prevent the over-shoot of the voltage. During the term, the output of amplifier is "H". After the output voltage reaches the set output voltage, they are balanced well. Herein, if the output pin would be short circuit, the output of amplifier would become "H" again, and the condition would continue for 2.0ms (Typ.), latch circuit would work and the output of LX would be latched with "OFF". (Output ="High-Z") If the output short is released before the latch circuit works (within 2ms after output shorted), the output of amplifier is balanced in the stable state again. Once the IC is latched, to release the protection, input "L" with CE pin, or make the supply voltage at UVLO level or less.
15
R1234D
TYPICAL CHARACTERISTICS
1) Output Voltage vs. Output Current
R1234D181A
1.90 1.90
R1234D181B
Output Voltage VOUT(V)
1.85
Output Voltage VOUT(V)
1.85
1.80 VIN=3.3V VIN=3.3V VIN=5.0V VIN=5.0V 1 PWM VFM PWM VFM 1000
1.80 VIN=3.3V VIN=3.3V VIN=5.0V VIN=5.0V 1 PWM VFM PWM VFM 1000
1.75
1.75
1.70 10 100 Output Current IOUT(mA)
1.70 10 100 Output Current IOUT(mA)
2) Efficiency vs. Output Current
R1234D181A
100 90 80 70 60 50 40 30 20 10 0 1 100 90 80 70 60 50 40 30 20 10 0 1
R1234D181B
VIN=3.3V VIN=3.3V VIN=5.0V VIN=5.0V
PWM VFM PWM VFM 1000
Efficiency (%)
Efficiency (%)
VIN=3.3V VIN=3.3V VIN=5.0V VIN=5.0V
PWM VFM PWM VFM 1000
10 100 Output Current IOUT(mA)
10 100 Output Current IOUT(mA)
3) Output Waveform (COUT=10F, tantalum, PWM)
R1234D181A
0.06 VIN=5V, IOUT=200mA ESR=400m
0.05
R1234D181B
VIN=5V, IOUT=10mA ESR=400m
Output Ripple Voltage(V)
Output Ripple Voltage(V)
0 1 2 3 4567 Time t(s) 8 9 10
0.04 0.02 0 -0.02 -0.04 -0.06 -0.08
0.04 0.03 0.02 0.01 0 -0.01 -0.02 -0.03 -0.04 0 1 2 3 4567 Time t(s) 8 9 10
16
R1234D
R1234D181B
VIN=5V, IOUT=200mA ESR=400m
R1234D181B
VIN=5V, IOUT=200mA ESR=200m
0.05 0.04 0.03 0.02 0.01 0 -0.01 -0.02 -0.03 -0.04 -0.05 -0.06 0 1 2 3
0.04
Output Ripple Voltage(V)
Output Ripple Voltage(V)
0.03 0.02 0.01 0 -0.01 -0.02 -0.03 -0.04 0 1 2 3 4567 Time t(s) 8 9 10
4567 Time t(s)
8
9 10
4) Load Transient Response (VIN=5.0V, PWM)
R1234D181A
300
Output Current IOUT(mA) Output Voltage VOUT(V) Output Voltage VOUT(V)
R1234D181B
300 Output Current 0mA 100mA 100 0
Output Current IOUT(mA) Output Current IOUT(mA)
200 Output Current 0mA 100mA 100 0
200
0.1 0 -0.1
Output Voltage
0.1 0 -0.1
Output Voltage
0
40 80 Time t (s)
120
160
0
40 80 Time t (s)
120
160
R1234D181A
300
Output Current IOUT(mA) Output Voltage VOUT(V)
R1234D181B
300
Output Voltage VOUT(V)
200 Output Current 0mA 200mA 100 0 Output Voltage
200 Output Current 0mA 200mA 100 0 Output Voltage
0.1 0
0.1 0 -0.1 -0.2 0
-0.1 0 40 80 Time t (s) 120 160
-0.2
40 80 Time t (s)
120
160
17
R1234D
R1234D181A
300
R1234D181B
300
Output Current IOUT(mA)
Output Current 100mA
2mA
100 0
Output Current 100mA
2mA 100 0
Output Voltage 0.1 0 -0.1 0 200 400 Time t (s) 600 800
0.1 0 -0.1
Output Voltage
0
200 400 Time t (s)
600
800
R1234D181A
300
Output Current IOUT(mA) Output Voltage VOUT(V)
Output Voltage VOUT(V)
R1234D181B
300 Output Current 100mA 0mA 100 0 0.2 0.1 0 -0.1 0 10 20 Time t (s) 30 40 Output Voltage
Output Current IOUT(mA) Output Current IOUT(mA)
200 Output Current 100mA 0mA 100 0 Output Voltage
200
0.1 0
-0.1 0 10 20 Time t (s) 30 40
R1234D181A
300
Output Current IOUT(mA) Output Voltage VOUT(V)
R1234D181B
300
Output Voltage VOUT(V)
200 Output Current 200mA 2mA 100 0 0.2 0.1 0 0 200 400 Time t (s) 600 800 Output Voltage
200 Output Current 200mA 2mA 100 0 0.2 0.1 0 -0.1 0 200 400 Time t (s) 600 800 Output Voltage
-0.1
18
Output Current IOUT(mA)
Output Voltage VOUT(V)
Output Voltage VOUT(V)
200
200
R1234D
R1234D181A
300
Output Current IOUT(mA) Output Voltage VOUT(V)
R1234D181B
300 Output Current 200mA 0mA 100 0 0.2 0.1 0 0 10 20 Time t (s) 30 40 Output Voltage
Output Current IOUT(mA) CE Input Voltage VCEL(V) CE Input Voltage VCEL(V) Output Voltage VOUT(V)
200 Output Current 200mA 0mA 100 0 0.2 0.1 0 0 10 20 Time t (s) 30 40 Output Voltage
200
-0.1
-0.1
5) Turn on speed with CE pin
R1234D181A
PWM, IOUT=0mA 4
R1234D181B
PWM, IOUT=0mA 4 2
CE Input Voltage VCEL(V)
Output Voltage VOUT(V)
2
CE Input Voltage
0 2 1 0
Output Voltage VOUT(V)
CE Input Voltage
0 2 1 0
Output Voltage
Output Voltage
0
0.4 0.8 1.2 1.6 2.0 2.4 2.8 Time t(s)
0
0.4 0.8 1.2 1.6 2.0 2.4 2.8 Time t(s)
R1234D181A
PWM, IOUT=50mA 4
R1234D181B
PWM, IOUT=50mA 4 2
CE Input Voltage VCEL(V)
Output Voltage VOUT(V)
2
Output Voltage VOUT(V)
CE Input Voltage
0 2 1 0
CE Input Voltage
0 2 1 0
Output Voltage
Output Voltage
0
0.4 0.8 1.2 1.6 2.0 2.4 2.8 Time t(s)
0
0.4 0.8 1.2 1.6 2.0 2.4 2.8 Time t(s)
19
R1234D
R1234D181A
PWM, IOUT=200mA 4
R1234D181B
PWM, IOUT=200mA 4 2
CE Input Voltage VCEL(V)
2
CE Input Voltage
0 2 1 0
CE Input Voltage
0 2 1 0
Output Voltage
Output Voltage
0
0.4 0.8 1.2 1.6 2.0 2.4 2.8 Time t(s)
0
0.4 0.8 1.2 1.6 2.0 2.4 2.8 Time t(s)
R1234D181A
VFM, IOUT=0mA 4
R1234D181B
VFM, IOUT=0mA 4 2
CE Input Voltage VCEH(V)
2
CE Input Voltage
0 2 1 0
CE Input Voltage
0 2 1 0
Output Voltage
Output Voltage
0
0.4 0.8 1.2 1.6 2.0 2.4 2.8 Time t(s)
0
0.4 0.8 1.2 1.6 2.0 2.4 2.8 Time t(s)
R1234D181A
VFM, IOUT=50mA 4
R1234D181B
VFM, IOUT=50mA 4 2
CE Input Voltage VCEH(V)
2
CE Input Voltage
0 2 1 0
CE Input Voltage
0 2 1 0
Output Voltage
Output Voltage
0
0.4 0.8 1.2 1.6 2.0 2.4 2.8 Time t(s)
0
0.4 0.8 1.2 1.6 2.0 2.4 2.8 Time t(s)
20
CE Input Voltage VCEH(V)
Output Voltage VOUT(V)
Output Voltage VOUT(V)
CE Input Voltage VCEH(V)
Output Voltage VOUT(V)
Output Voltage VOUT(V)
CE Input Voltage VCEL(V)
Output Voltage VOUT(V)
Output Voltage VOUT(V)
R1234D
6) Output Ripple Voltage vs. Output Current
R1234D181B
80 COUT=10F, Tantalum, ESR=400m 1.90
7) Output Voltage vs. Temperature
R1234D181B
IOUT=100mA
Output Ripple Voltage(mV)
60 50 40 30 20 10 0 50 100 150 200 250 300 350 400 450 500 Output Current IOUT(mA) VIN=3.3V VIN=5.0V
Output Voltage VOUT(V)
70
1.85
1.80
1.75
1.70 -40 -25
0 25 50 Temperature Topt(C)
75 85
8) Output Voltage vs. Input Voltage
R1234D181B
2.00 IOUT=20mA
9) Frequency vs. Temperature
VIN =VOUT+1.5V
1000 900
Output Voltage VOUT(V)
1.95
Frequency f(kHz)
1.90 1.85 1.80 1.75 1.70 1.65 1.60 2 3 4 5 Input Voltage VIN(V) 6
800 700 600 500 400 300 -40 -25 0 25 50 Temperature Topt(C) 75 85 800kHz 500kHz
10) Supply Current vs. Temperature
11) Soft-start Time vs. Temperature
R1234D181B
VIN =3.3V 3.0
450
VIN =5.5V
Supply Current IDD(A)
400 350 300 250 200 150 100 -40 -25 0 25 50 Temperature Topt(C) 75 85 800kHz 500kHz
Soft-start Time tstart(ms)
2.5 2.0 1.5 1.0 0.5 0 -40 -25 800kHz 500kHz
0 25 50 Temperature Topt(C)
75 85
21
R1234D
12) UVLO Threshold vs. Temperature
2.3 2.2 2.1 2.0 1.9 1.8 -40 -25 UVLO Released Voltage UVLO Threshold Voltage 0 25 50 Temperature Topt(C) 75 85
13) CE Input Voltage vs. Temperature
1.6
CE Input Voltage VCE(V)
1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 -40 -25 CE Input Voltage(V) "H" CE Input Voltage(V) "L" 0 25 50 Temperature Topt(C) 75 85
14) Mode Input Voltage vs. Temperature
1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 -40 -25 MODE Input Voltage "H" MODE Input Voltage "L" 0 25 50 Temperature Topt(C) 75 85
UVLO Voltage(V)
15) Maximum Duty Cycle at VFM Mode vs. Temperature
80
VFM Duty Cycle VFMduty(%)
Mode Input Voltage VMODE(V)
75 70 65 60 55 50 -40 -25
0 25 50 Temperature Topt(C)
75 85
16) Lx Transistor On Resistance vs. Temperature
1.00 0.40
17) Lx Limit Voltage vs. Temperature
Lx Limit Voltage VLXlim(V)
75 85
ON Resistance RON()
0.35 0.30 0.25 0.20 0.15 0.10 -40 -25
0.75 NchTr 0.50
0.25 PchTr 0 -40 -25
0 25 50 Temperature Topt(C)
0 25 50 Temperature Topt(C)
75 85
22
R1234D
18) Protection Delay Time vs. Temperature
Protaction Delay Time tprot(ms)
3.0 2.4 1.8 1.2 0.6 0 -40 -25
0 25 50 Temperature Topt(C)
75 85
23
PACKAGE INFORMATION
PE-SON-8-0611
*
SON-8
Unit: mm
PACKAGE DIMENSIONS
2.90.2 0.475Typ. 8 5
0.230.1 0.20.1
Bottom View 0.130.05 0.15 +0.1 -0.15 0.15 +0.1 -0.15
2.80.2 3.00.2
1
4 Attention : Tab suspension leads in the parts have VDD or GND level. (They are connected to the reverse side of this IC.) Refer to PIN DISCRIPTION. Do not connect to other wires or land patterns.
0.130.05
0.65 0.30.1
0.1 0.1 M
TAPING SPECIFICATION
0.20.1 +0.1 1.50 4.00.1 2.00.05
0.9Max.
3.50.05
1.10.1
0 180 -1.5 60 +1 0
1.750.1
3.3 2.0Max. 4.00.1
TR User Direction of Feed
TAPING REEL DIMENSIONS
(1reel=3000pcs)
REUSE REEL (EIAJ-RRM-08Bc)
11.41.0 9.00.3
130.2
210.8
20.5
8.00.3
3.2
0.20.1
PACKAGE INFORMATION
PE-SON-8-0611
POWER DISSIPATION (SON-8)
This specification is at mounted on board. Power Dissipation (PD) depends on conditions of mounting on board. This specification is based on the measurement at the condition below: Measurement Conditions Standard Land Pattern Environment Board Material Board Dimensions Copper Ratio Through-hole Measurement Result
(Topt=25C,Tjmax=125C)
Mounting on Board (Wind velocity=0m/s) Glass cloth epoxy plactic (Double sided) 40mm x 40mm x 1.6mm Top side : Approx. 50% , Back side : Approx. 50% 0.5mm x 44pcs
Standard Land Pattern Power Dissipation Thermal Resistance
600
Free Air 300mW 333C/W
480mW ja=(125-25C)/0.48W=208C/W
Power Dissipation PD(mW)
500 400 300
480
On Board
40
Free Air
100 0 0 25 50 75 85 100 Ambient Temperature (C) 125 150
Power Dissipation
40
200
Measurement Board Pattern IC Mount Area (Unit : mm)
RECOMMENDED LAND PATTERN
0.35 0.65
1.15
0.65
(Unit: mm)
MARK INFORMATION
ME-R1234D-0608
R1234D SERIES MARK SPECIFICATION * SON-8
1 5
to ,
6
4
: Product Code (refer to Part Number vs. Product Code) : Lot Number
1
2
3
4
R
5
6
*
Part Number vs. Product Code
Product Code
1 2 3 4
Part Number R1234D121A R1234D131A R1234D141A R1234D151A R1234D161A R1234D171A R1234D181A R1234D191A R1234D201A R1234D211A R1234D221A R1234D231A R1234D241A R1234D251A R1234D261A R1234D271A R1234D281A R1234D291A R1234D301A R1234D311A R1234D321A R1234D331A
Part Number R1234D121B R1234D131B R1234D141B R1234D151B R1234D161B R1234D171B R1234D181B R1234D191B R1234D201B R1234D211B R1234D221B R1234D231B R1234D241B R1234D251B R1234D261B R1234D271B R1234D281B R1234D291B R1234D301B R1234D311B R1234D321B R1234D331B
Product Code
1 2 3 4
Part Number R1234D001C R1234D001D
Product Code
1 2 3 4
H H H H H H H H H H H H H H H H H H H H H H
1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 3 3
2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
A A A A A A A A A A A A A A A A A A A A A A
H H H H H H H H H H H H H H H H H H H H H H
1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 3 3
2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
B B B B B B B B B B B B B B B B B B B B B B
H H
0 0
1 1
C D

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