2002.10.15 Step-down DC/DC Converter with Reset R5210X Serie

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2002.10.15 Step-down DC/DC Converter with Reset R5210X Serie

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OUTLINE
2002.10.15
Step-down DC/DC Converter with Reset
R5210X Series
R5210X CMOS-based step-down DC/DC converter combined with voltage regulator (VR) voltage detector (VD), with supply current. Each these consists oscillator, control circuit, reference voltage unit, error amplifier, soft-start circuit, current limit circuit, phase compensation circuit, resistor voltage detect circuit, output driver transistor, ripple, high efficiency step-down DC/DC converter easily composed this with some external components, inductor, diode, capacitors. oscillator frequency 800kHz, therefore small inductor capacitor used with this Further, this equips under voltage lockout function (UVLO). input voltage becomes 2.35V (Typ.) less, output DC/DC converter turned off. However, embedded voltage regulator detector continue operate. voltage regulator consists reference voltage unit, resistor voltage detect circuit, error amplifier, output driver transistor, built-in voltage detector supervises input voltage output N-channel open drain type. Power-on reset delay time also included internally typically 10ms.
FEATURES
Wide Range Input Voltage Built-in Soft-start Function (Typ. 2ms) built-in power-on reset delay (Typ. 10ms) Maximum Output Current 200mA(VR) High Accuracy Output Voltage Voltage Regulator Output) Accuracy voltage detector Output Voltage(VR) Setting with step 0.1V range 2.5V 3.6V Output Voltage(DC/DC) Stepwise Setting with step 0.1V range 1.5V 3.3V Output Voltage(VD) Setting with step 0.1V range 3.0V 4.5V Packages SOT23-6W(thickness: Max. 1.3mm) HSON6(thickness: Max. 0.9mm)
APPLICATIONS
Power source hand-held communication equipment, drives. Power source battery-powered equipment.
Rev. 1.12
BLOCK DIAGRAM
Current Limit CONTROL
VOUT1
OUTPUT
Current Limit
CONTROL Soft Start
Vref
Vref
U.V.L.O. Delay Circuit
VOUT2
Vref
VDOUT
SELECTION GUIDE
R5210X Series, output voltage combination selected user's request. selection made with designating part number shown below;
R5210XXXXX-TR Part Number
Code
Contents Designating Package type: SOT23-6W HSON6(Under Development) Output Voltage Combination Code Number Designation Optional Function (Standard) Designation Taping Type: Refer Taping specification.
Rev. 1.12
CONFIGURATIONS
SOT-23-6W
(Mark side)
R5210NXXXX HSON6
(Mark side)
R5210DXXXX
DESCRIPTION
R5210N R5210D Symbol VOUT2 VDOUT VOUT1 Description Output Voltage Regulator Output Voltage Detector (N-channel open-drain output type) DC/DC converter Step-down Output monitoring Switching (P-channel open-drain output type) Ground Voltage Supply
Rev. 1.12
ABSOLUTE MAXIMUM RATINGS
Symbol VOUT1 VOUT2 VDOUT IOUT2 Topt Tstg Item Voltage Voltage VOUT1 Voltage VOUT2 Voltage VDOUT Voltage Output Current VOUT2 Output Current Power Dissipation(SOT23-6W) Power Dissipation (HSON-6/Under Development) Operating Temperature Range Storage Temperature Range Rating -0.3VIN+0.3 -0.3VIN+0.3 -0.3VIN+0.3 -0.3VIN+0.3 -40+85 -55+125
(GND=0V) Unit
GR5210N001C Symbol Item Operating Input Voltage Supply Current VUVLO1 UVLO Detector Threshold Voltage VUVLO2 UVLO Release Voltage
ELECTRICAL CHARACTERISTICS
Conditions VIN=5.0V, VOUT1=5.0V
(Topt=25°C) Typ. Max. Unit 2.15 VUVLO2 -0.15 2.35 2.50 2.65 Min. Min. 2.646 Typ. 2.700 ±100 0.01 Max. Unit 2.754 kHz/ 5.00
DC/DC Part Symbol Item Conditions VOUT1 DC/DC Output Voltage VIN=5.0V, load VOUT1/ DC/DC Output Voltage -40°C Topt 85°C Temperature Coefficient fOSC Oscillator Frequency VIN=5.0V fOSC/ Oscillator Frequency Temperature -40°C Topt 85°C Coefficient Resistance VIN=5.0V, ILX=100mA ILXleak Leakage Current VIN=VOUT1=5.0V, VLX=0V ILxlim Current Limit VIN=5.0V Maxdty Maximum duty cycle Tstart Soft-start Time VIN=5.0V part Symbol VOUT2 IOUT2 VREG2 VDIF2 ILIM2 VOUT2/
Item Output Voltage Maximum Output Current Load Regulation Dropout Voltage Short Current Limit Output Voltage Temperature Coefficient
Conditions VIN=5.0V, IOUT2=10mA VIN=5.0V VIN=5.0V, 1mAIOUT280mA IOUT2=100mA VOUT2=0V -40°C Topt 85°C
Min. 3.332
Typ. 3.400 ±100
Max. Unit 3.468
Rev. 1.12
part Symbol -VDET -VDET/ VHYS tpLH IDOUTL
Item Detector Threshold Detector Threshold Temperature Coefficient Hysteresis Range Output Delay Time Release VDOUT Output Current
Conditions -40°C Topt 85°C
Min. 4.095
Typ. 4.200 ±100 -VDET
Max. Unit 4.305
VIN=2.0V, VDOUT=0.1V
TYPICAL APPLICATION APPLICATION HINTS
R5210NXXXC
VOUT2 VDOUT
VOUT2
VDOUT
VOUT1
VOUT1
Examples Components Inductor LQH4C (Murata, 10µH) LDR655312T (TDK) Shottky Diode RB491D (Rohm) EP05Q03L (Nihon Inter), Pull-up Resistor Capacitors: C1=10µF (Ceramic Capacitor) 22µF (Tantalum Capacitor) 10µF (Tantalum Capacitor) When these ICs, consider following issues; external components close possible minimize connection between components particular, capacitor should connected between with minimum connection. Make sufficient grounding, reinforce supplying. large switching current flows through connection powersupply, inductor connection VOUT1. impedance connection power supply ground high, thevoltage level power supply fluctuates with switching current. This cause unstable operation ofthe capacitor with capacity 10µF more GND, with ceramic type. terms VOUT1, capacitor with capacity 22µF more, with good high frequency characteristics such tantalum capacitors. Choose inductor that sufficiently small D.C. resistance large allowable current which hard reach magnetic saturation. value inductance inductor extremely small, ILX, which flows through transistor inductor, exceed absolute maximum rating maximum loading. inductor with appropriate inductance.
Rev. 1.12
diode Schottky type with high switching speed, also attention current capacity. spike noise large, make snub circuit (such serial connection between GND, then noise will reduced. time constant depends actual PCB, evaluate actual PCB. load current voltage regulator small, because switching noise DC/DC converter, output voltage VOUT2 large. avoid this, voltage regulator with load current least 1mA.
performance power source circuits using these extremely depends upon peripheral circuits. attention selection peripheral circuits. particular, design peripheral circuits that values such voltage, current, power each component, patterns exceed their respected rated values.
OPERATION step-down DC/DC converter Output Current
step-down DC/DC converter charges energy inductor when transistor discharges energy from inductor when transistor controls with less energy loss, that lower output voltage than input voltage obtained. operation will explained with reference following diagrams: <Basic Circuits> IOUT T=1/fosc toff VOUT ILmin <Current through ILmax topen
Step turns current (=i1) flows, energy charged into this moment, increases from ILmin (=0) reach ILmax proportion on-time period (ton) Step When turns off, Schottky diode (SD) turns order that maintains ILmax, current (=i2) flows. Step decreases gradually reaches ILmin after time period topen, turns off, provided that continuous mode, next cycle starts before becomes because toff time enough. this case, value from this ILmin (>0). case control system, output voltage maintained controlling on-time period (ton), with oscillator frequency (fosc) being maintained constant. Discontinuous Conduction Mode Continuous Conduction Mode maximum value (ILmax) minimum value (ILmin) current which flow through inductor same those when turns when turns off. difference between ILmax ILmin, which represented ILmax ILmin VOUT topen Where, T=1/fosc=ton+toff duty fosc topen toff Equation respectively shown change current change current OFF.
Rev. 1.12
When output current (IOUT) relatively small, topen toff illustrated above diagram. this case, energy charged inductor during time period discharged entirely during time period toff, therefore ILmin becomes zero (ILmin=0). When Iout gradually increased, eventually, topen becomes toff (topen=toff), when IOUT further increased, ILmin becomes larger than zero (ILmin>0). former mode referred discontinuous mode latter mode referred continuous mode. continuous mode, when Equation solved assumed that solution tonc, Equation When ton<tonc, mode discontinuous mode, when ton=tonc, mode continuous mode.
OUTPUT CURRENT SELECTION EXTERNAL COMPONENTS
When "ON": (Wherein, Ripple Current value described IRP, resistance described direct current inductor described RL.) Equation When "OFF": Equation Equation Equation solve duty, ton/(toff+ton)=DON, Ripple Current follows; .Equation Wherein, peak current that flows through Tr., follows; ILmax=IOUT+IRP/2.Equation Consider ILmax, condition input output select external components. #The above explanation directed calculation ideal case continuous mode.
Rev. 1.12
Timing Chart
Vdet+Vhys) Vdet UVLO2 VUVLO1
Voltage
Soft-start Time
OUT1 Voltage
Voltage
VDDelay Release VDOUT
Delay Release
Voltage
OUT2
Voltage
timing chart which shown previous page describes relation supply voltage changes with time each output DC/DC converter, voltage detector, voltage regulator. DC/DC converter When power turns case rising voltage, while voltage UVLO release level (VUVLO2) less, operation DC/DC converter stops does make switching, therefore VOUT1 voltage does rise. When voltage becomes UVLO release level more, DC/DC converter starts soft-start operation, start switching, then VOUT1 will rise. After soft-start time, voltage becomes VOUT1 level more, VOUT1 will settled VOUT1 output voltage. voltage becomes UVLO detector threshold level (VUVLO1) less, DC/DC converter stops switching then transistor turns off. Voltage Detector voltage detector threshold level less, N-channel transistor VDOUT turns outputs VDOUT pin. Then, when voltage becomes detector threshold level hysteresis range (-VDET+VHYS) more, after delay release (tpLH) passing, N-channel transistor inside turns off, VDOUT voltage reaches pull-up voltage. Besides, release circuit starts after soft-start time under this condition, voltage should (-VDET+VHYS) more. Voltage Regulator voltage regulator always operates even UVLO function would work. Therefore, VOUT2 voltage nearly equal voltage. Actual value depends load current. When voltage becomes VOUT2 voltage more, VOUT2 voltage will output voltage.
Supply Current Rev. 1.12
TEST CIRCUITS
UVLO Detector Threshold/ Released Voltage
OSCILLOSCOPE
VOUT1
VOUT1
Leakage Current
VOUT1
Resistance
VOUT1
Current Limit
OSCILLOSCOPE
VOUT1 Output Voltage
OSCILLOSCOPE
VOUT1
VOUT1
VOUT2
Rev. 1.12
Oscillator Frequency, Soft-start Time
OUT1
OUT1
VOUT2 Output Voltage, Load Regulation, Dropout Voltage, Current Limit, Short Current Limit
VDOUT Detector Threshold, Hysteresis Range, Output Delay Time Release
VOUT1
VOUT1
VOUT2
IOUT2
DOUT OSCILLOSCO CILLOSCOPE
VDOUT Output Current
VOUT1
DOUT DOUT
Typical Characteristics were obtained with using test circuits follows; Typical Application Circuit: Typical Characteristics Test Circuit Typical Characteristics Test Circuit Typical Characteristics Test Circuit Typical Characteristics Test Circuit Typical Characteristics
Rev. 1.12
TYPICAL CHARACTERISTICS
Output Voltage Output Current
L1=22uH,C1=10uF R5210N001C VOUT1=2.7V,IOUT2=0mA Output Voltage VOUT1[V] 2.75 Efficiency Output Current IOUT1[mA] Output Current IOUT1 [mA] VIN=4.5V VIN=5.0V VIN=5.5V
Efficiency Output Current
L1=22uH,C1=10uF R5210N001C VOUT1=2.7V,IOUT2=0mA
2.65
Vin=4.5V Vin=5.0V Vin=5.5V
DC/DC Output Voltage Temperature
R5210N001C 2.80 Output Voltage VOUT1
Output Voltage Temperature
R5210N001C 3.50 Output Voltage VOUT2
2.75
3.45
2.70
3.40
2.65
3.35
2.60 Temperature Topt (°C)
3.30 Temperature Topt (°C)
Detector Threshold Temperature
R5210N001C
Oscillator Frequency Temperature
R5210N001C 1000
Detector Threshold -VDET
Frequency Fosc [kHz]
Temperature Topt (°C)
Temperature Topt (°C)
Rev. 1.12
Soft-start time Temperature
R5210N001C
Output Delay Time Release Temperature
R5210N001C Output Delay Time Release tPLH [msec]
Soft-start Time [msec]
Temperature Topt (°C)
Temperature Topt(°C)
Output Voltage Output Current
R5210N001C Output Voltage VOUT2
Output Voltage Output Current (zoomed)
R5210N001C 3.43 3.42 Output Voltage VOUT2 3.41 3.39 3.38 3.37 3.36
Output Current IOUT2 [mA]
Output Current IOUT2 [mA]
Load Transient Response
Load Transient Response
Rev. 1.12

2002.10.15 Step-down DC/DC Converter with Reset R5210X Serie

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