R5212D SERIES
Step-down DC/DC Converter with VR and Reset
NO.EA-128-0510
OUTLINE
The R5212D is CMOS-based PWM step-down DC/DC converter combined with a voltage regulator (VR) and a voltage detector (VD), with low supply current. Each of these ICs consists of an oscillator, a PWM control circuit, a voltage reference unit, an error amplifier, a soft-start circuit, a current limit circuit, a phase compensation circuit, a resistor net for voltage detect circuit, an output driver transistor, and so on. A low ripple, high efficiency step-down DC/DC converter can be easily composed of this IC with some external components, or an inductor, a diode, and capacitors. The oscillator frequency is 1.2MHz, therefore small inductor and capacitor can be used with this IC. Further, this IC equips the under voltage lockout function (UVLO). If the input voltage becomes equal or less than 2.35V (Typ.), the output of DC/DC converter turns off. However, in the A/B version, embedded voltage regulator and detector continue to operate. In the C/D version, LDO output also turns off and only the voltage detector is working. The voltage regulator consists of a voltage reference unit, a resistor net for voltage detect circuit, an error amplifier, an output driver transistor, and so on. The input source voltage of the built-in voltage regulator is VIN pin (A/B version) or VOUT1 pin, the output of DC/DC converter (C/D version). The built-in voltage detector supervises the input voltage and the output is N-channel open drain. Power-on reset delay time is also included and internally set typically at 12ms (A/C version) or 50ms(B/D version).
FEATURES
• • • • • • Range of Input Voltage ............................. 3.0V~5.5V Built-in Soft-start Function (Typ. 1ms) and built-in power-on reset delay (Typ. 12ms or 50ms) Maximum Output Current...........................500mA (DC/DC), 200mA (VR) Accuracy Output Voltage .......................... ±2.0% (DC/DC and Voltage Regulator Output) Accuracy of voltage detector .................... ±2.5% Output Voltage (VR)(A/B Version) ............ Stepwise Setting with a step of 0.1V in the range of 2.0V to 3.6V (C/D Version) ............ Stepwise Setting with a step of 0.1V in the range of 1.2V to 3.0V • Output Voltage (DC/DC) (A/B Version) ..... Stepwise Setting with a step of 0.1V in the range of 1.2V to 3.6V (C/D Version) ..... Stepwise Setting with a step of 0.1V in the range of 2.5V to 3.6V • Output Voltage (VD).................................. Stepwise Setting with a step of 0.1V in the range of 3.0V to 4.5V • Package .................................................... HSON-6 (t=0.9mm)
APPLICATIONS
• Power source for hand-held communication equipment, CD or DVD drives. • Power source for battery-powered equipment.
1
R5212D
BLOCK DIAGRAMS
R5212xxxA/B
VIN
6
Current Limit
OSC
4 VOUT1 LX 1
Output Control Logic Vref Current Limit Vref Soft Start
U.V.L.O. Delay Circuit Vref
5 VOUT2
3
VDOUT
2
GND
R5212DxxxC/D
VIN
6
Current Limit & Feedback
OSC
4
VOUT1
LX
1
Output Control Logic Soft Start
Vref
Current Limit U.V.L.O. Delay Circuit Vref
5
Vref
VOUT2
3 VDOUT
2
GND
2
R5212D
SELECTION GUIDE
In the R5212D Series, the output voltage combination for the ICs can be selected at the user’s re-quest. The selection can be made with designating the part number as shown below;
R5212Dxxxx-TR
↑↑ ab Code a ↑ c
←Part Number
Contents Output Voltage Combination Code Number Designation of Optional Function A: VR input pin=VIN pin, VD delay=12ms B: VR input pin=VIN pin, VD delay=50ms C: VR input pin=DC/DC Output, VD delay=Typ. 12ms D: VR input pin=DC/DC Output, VD delay=Typ. 50ms Designation of Taping Type: Refer to Taping specification.
b
c
3
R5212D
PIN CONFIGURATION
HSON-6 Top View
6 5 4
Bottom View
4 5 6
1
2
3
3
2
1
PIN DESCRIPTIONS
Pin No 1 2 3 4 5 6 Symbol LX GND VDOUT VOUT1 VOUT2 VIN Ground Pin Output Pin of Voltage Detector (N-channel open-drain out-put type) DC/DC converter Step-down Output monitoring Pin Output Pin of Voltage Regulator Voltage Supply Pin Pin Description Switching Pin (P-channel open-drain output type)
∗ 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
(GND=0V)
Symbol VIN VLX VOUT1 VOUT2 VDOUT ILX IOUT2 PD Topt Tstg VIN Pin Voltage Lx Pin Voltage VOUT1 Pin Voltage VOUT2 Pin Voltage VDOUT Pin Voltage
Item
Rating 6.5 −0.3 ~ VIN+0.3 −0.3 ~ VIN+0.3 −0.3 ~ VIN+0.3 −0.3 ~ 6.5 800 400
∗1
Unit V V V V V mA mA mW °C °C
Lx Pin Output Current VOUT2 Pin Output Current Power Dissipation (On Board) Storage Temperature Range Operating Temperature Range
900 −40 ~ +85 −55 ~ +125
∗1 ) For Power Dissipation please refer to PACKAGE INFORMATION to be described.
4
R5212D
ELECTRICAL CHARACTERISTICS
•
R5212DxxxA
Symbol VIN IDD VUVLO2 VUVLOHYS Item Operating Input Voltage Supply Current UVLO Release Voltage UVLO Detector Threshold Voltage Hysteresis VIN=5.0V, VOUT1=0V 2.35 0.05 Conditions Min. 3.0 400 2.50 0.15 Typ. Max. 5.5 800 2.65 0.25
Topt=25°C
Unit V µA V V
Topt=25°C
•
DC/DC Part
Symbol VOUT1 ∆VOUT1/ ∆Topt fosc RLX ILXleak ILXLIM Maxduty tstart Item DC/DC Output Voltage DC/DC Output Voltage Temperature Coefficient Oscillator Frequency Lx on Resistance Lx Leakage Current Lx Current Limit Maximum duty cycle Soft-start Time VIN=5.0V Conditions VIN=5.0V, at no load OPEN LOOP 40°C
< =
Min. VOUT1 ×0.98
Typ.
Max. VOUT1 ×1.02
Unit V ppm /°C
Topt
< =
85 ° C 960
±100 1200 0.4 0.01 600 100 0.35 1.00 3.00 800 1440 0.8 5.00
VIN=5.0V VIN=5.0V, ILX=100mA VIN=VOUT1=5.5V, VLX=0V VIN=5.0V
kHz Ω µA mA % ms
Topt=25°C
•
VR Part
Symbol VOUT2 IOUT2 VREG2 VDIF2 ILIM2 ∆VOUT2/ ∆Topt Item VR Output Voltage Maximum Output Current of VR VR Load Regulation Dropout Voltage Short Current Limit VR Output Voltage Temperature Coefficient Conditions VIN=5.0V, IOUT2=10mA VIN=5.0V VIN−VOUT2=0V 1mA < IOUT2 < 80mA = = IOUT2=100mA VOUT2=0V 40°C
< =
Min. VOUT2 ×0.98 200
Typ.
Max. VOUT2 ×1.02 60 0.3
Unit V mA
20 0.2 50
mV V mA ppm /°C
Topt=25°C
Topt
< =
85 ° C
±100
•
VD Part
Symbol −VDET ∆−VDET/ ∆Topt VHYS tPLH IDOUTL Item VD Detector Threshold VD Detector Threshold Temperature Coefficient Hysteresis Range
VD Output Delay Time for Release
Conditions
Min. −VDET ×0.975
Typ.
Max. −VDET ×1.025
Unit V ppm /°C V
40°C
< =
Topt
< =
85 ° C
±100 −VDET
×0.05
VIN=VDOUT=−VDET×0.9 to 5.0 VIN=2.0V, IOUT=0.1V
3 2
12 7
30 20
ms mA
VDOUT “L” Output Current
5
R5212D
•
R5212DxxxB
Symbol VIN IDD VUVLO2 VUVLOHYS Item Operating Input Voltage Supply Current UVLO Release Voltage UVLO Detector Threshold Voltage Hysteresis VIN=5.0V, VOUT1=0V 2.35 0.05 Conditions Min. 3.0 400 2.50 0.15 Typ. Max. 5.5 800 2.65 0.25
Topt=25°C
Unit V µA V V
Topt=25°C
•
DC/DC Part
Symbol VOUT1 ∆VOUT1/ ∆Topt fosc RLX ILXleak ILXLIM Maxduty tstart Item DC/DC Output Voltage DC/DC Output Voltage Temperature Coefficient Oscillator Frequency Lx on Resistance Lx Leakage Current Lx Current Limit Maximum duty cycle Soft-start Time VIN=5.0V Conditions VIN=5.0V, at no load OPEN LOOP 40°C
< =
Min. VOUT1 ×0.98
Typ.
Max. VOUT1 ×1.02
Unit V ppm /°C
Topt
< =
85 ° C 960
±100 1200 0.4 0.01 600 100 0.35 1.00 3.00 850 1440 0.8 5.00
VIN=5.0V VIN=5.0V, ILX=100mA VIN=VOUT1=5.5V, VLX=0V VIN=5.0V
kHz Ω µA mA % ms
Topt=25°C
•
VR Part
Symbol VOUT2 IOUT2 VREG2 VDIF2 ILIM2 ∆VOUT2/ ∆Topt Item VR Output Voltage Maximum Output Current of VR VR Load Regulation Dropout Voltage Short Current Limit VR Output Voltage Temperature Coefficient Conditions VIN=5.0V, IOUT2=10mA VIN=5.0V VIN−VOUT2=0V 1mA < IOUT2 < 80mA = = IOUT2=100mA VOUT2=0V 40°C
< =
Min. VOUT2 ×0.98 200
Typ.
Max. VOUT2 ×1.02 60 0.3
Unit V mA
20 0.2 50
mV V mA ppm /°C
Topt=25°C
Topt
< =
85 ° C
±100
•
VD Part
Symbol −VDET ∆−VDET/ ∆Topt VHYS tPLH IDOUTL Item VD Detector Threshold VD Detector Threshold Temperature Coefficient Hysteresis Range VD Output Delay Time for Release VDOUT “L” Output Current VIN=VDOUT=−VDET×0.9 to 5.0 VIN=2.0V, VDOUT=0.1V 3 2 40°C
< =
Conditions
Min. −VDET ×0.975
Typ.
Max. −VDET ×1.025
Unit V ppm /°C V
Topt
< =
85 ° C
±100 −VDET ×0.05 12 7 30 20
ms mA
6
R5212D
•
R5212DxxxC
Symbol VIN IDD VUVLO2 VUVLOHYS Item Operating Input Voltage Supply Current UVLO Release Voltage UVLO Detector Threshold Voltage Hysteresis VIN=5.0V, VOUT1=0V 2.35 0.05 Conditions Min. 3.0 400 2.50 0.15 Typ. Max. 5.5 800 2.65 0.25
Topt=25°C
Unit V µA V V
Topt=25°C
•
DC/DC Part
Symbol VOUT1 ∆VOUT1/ ∆Topt fosc RLX ILXleak ILXLIM Item DC/DC Output Voltage DC/DC Output Voltage Temperature Coefficient Oscillator Frequency Lx on Resistance Lx Leakage Current Lx Current Limit Maximum duty cycle Soft-start Time VIN=5.0V Conditions VIN=5.0V, at no load OPEN LOOP 40°C
< =
Min. VOUT1 ×0.98
Typ.
Max. VOUT1 ×1.02
Unit V ppm /°C
Topt
< =
85 ° C 960
±100 1200 0.4 0.01 600 100 0.35 1.00 3.00 850 1440 0.8 5.00
VIN=5.0V VIN=5.0V, ILX=100mA VIN=VOUT1=5.5V, VLX=0V VIN=5.0V
kHz Ω µA mA % ms
Topt=25°C
Maxduty tstart
•
VR Part
Symbol VOUT2 IOUT2 VREG2 VDIF2 ILIM2 ∆VOUT2/ ∆Topt Item VR Output Voltage Conditions VOUT1=3.3V IOUT2=10mA VIN−VOUT2=0V 1mA < IOUT2 < 80mA = = IOUT2=100mA VOUT2=0V 40°C
< =
Min. VOUT2 ×0.98 200
Typ.
Max. VOUT2 ×1.02
Unit V mA
Maximum Output Current of VR VIN=5.0V VR Load Regulation Dropout Voltage Short Current Limit VR Output Voltage Temperature Coefficient
20 0.2 50
60 0.3
mV V mA ppm /°C
Topt=25°C
Topt
< =
85 ° C
±100
•
VD Part
Symbol −VDET ∆−VDET/ ∆Topt VHYS tPLH IDOUTL Item VD Detector Threshold VD Detector Threshold Temperature Coefficient Hysteresis Range VD Output Delay Time for Release VDOUT “L” Output Current VIN=VDOUT=−VDET×0.9 to 5.0 VIN=2.0V, VDOUT=0.1V 3 2 40°C
< =
Conditions
Min. −VDET ×0.975
Typ.
Max. −VDET ×1.025
Unit V ppm /°C V
Topt
< =
85 ° C
±100 −VDET ×0.05 12 7 30 20
ms mA
7
R5212D
•
R5212DxxxD
Symbol VIN IDD VUVLO2 VUVLOHYS Item Operating Input Voltage Supply Current UVLO Release Voltage UVLO Detector Threshold Voltage Hysteresis VIN=5.0V, VOUT1=0V 2.35 0.05 Conditions Min. 3.0 400 2.50 0.15 Typ. Max. 5.5 800 2.65 0.25
Topt=25°C
Unit V µA V V
Topt=25°C
•
DC/DC Part
Symbol VOUT1 ∆VOUT1/ ∆Topt fosc RLX ILXleak ILXLIM Maxduty tstart Item DC/DC Output Voltage DC/DC Output Voltage Temperature Coefficient Oscillator Frequency Lx on Resistance Lx Leakage Current Lx Current Limit Maximum duty cycle Soft-start Time VIN=5.0V Conditions VIN=5.0V, at no load OPEN LOOP 40°C
< =
Min. VOUT1 ×0.98
Typ.
Max. VOUT1 ×1.02
Unit V ppm /°C
Topt
< =
85 ° C 960
±100 1200 0.4 0.01 600 100 0.35 1.00 3.00 850 1440 0.8 5.00
VIN=5.0V VIN=5.0V, ILX=100mA VIN=VOUT1=5.5V, VLX=0V VIN=5.0V
kHz Ω µA mA % ms
Topt=25°C
•
VR Part
Symbol VOUT2 IOUT2 VREG2 VDIF2 ILIM2 ∆VOUT2/ ∆Topt Item VR Output Voltage Maximum Output Current of VR VR Load Regulation Dropout Voltage Short Current Limit VR Output Voltage Temperature Coefficient Conditions VOUT1=3.3V IOUT2=10mA VIN=5.0V, VOUT1=3.3V VIN−VOUT2=0V 1mA < IOUT2 < 80mA = = IOUT2=100mA VOUT2=0V 40°C
< =
Min. VOUT2 ×0.98 200
Typ.
Max. VOUT2 ×1.02
Unit V mA
20 0.2 50
60 0.3
mV V mA ppm /°C
Topt=25°C
Topt
< =
85 ° C
±100
•
VD Part
Symbol −VDET ∆−VDET/ ∆Topt VHYS tPLH IDOUTL Item VD Detector Threshold VD Detector Threshold Temperature Coefficient Hysteresis Range VD Output Delay Time for Release VDOUT “L” Output Current VIN=VDOUT=−VDET×0.9 to 5.0 VIN=2.0V, VDOUT=0.1V 10 2 40°C
< =
Conditions
Min. −VDET ×0.975
Typ.
Max. −VDET ×1.025
Unit V ppm /°C V
Topt
< =
85 ° C
±100 −VDET ×0.05 50 7 120 20
ms mA
8
R5212D
TYPICAL APPLICATION AND APPLICATION HINTS
R5212Dxxxx
C3 VOUT2 VDOUT R1 VOUT2 VDOUT VOUT1 VIN GND LX L1 D1 C2 VOUT1 C1
Examples of Components Symbol (VOUT1 L1
< =
Item 1.6V) 4.7µH 4.7µH (VOUT1 > 1.6V) 6.8µH 6.8µH LQH43C Series VLP5610 Series LQH43C Series VLP5610 Series Murata TDK Murata TDK
D1 R1 C1 C2 C3
RB491D(ROHM) or EP05Q03 (Nihon Inter) 50kΩ 10µF Ceramic Capacitor 10µF Ceramic Capacitor 2.2µF Ceramic Capacitor
9
R5212D
When you use these ICs, consider the following issues; 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 between VIN and GND with the minimum connection. Make sufficient grounding, and reinforce supplying. A large switching current may flow through the connection of power supply, an inductor and the connection of VOUT1. If the impedance of the connection of power supply or ground is high, the voltage level of power supply of the IC fluctuates with the switching current. This may cause unstable operation of the IC. Use a capacitor with a capacity of 10µF or more for VIN and GND, and with low ESR ceramic type. In terms of VOUT1, use a ceramic capacitor with a capacity of 10µF or more. For VOUT2 pin, use a ceramic capacitor with a capacitance of 2.2µF or around. Choose an inductor that has a small D.C. resistance and large allowable current and which is hard to reach magnetic saturation. If the value of inductance of an inductor is extremely small, the ILX , which flows through Lx transistor and an inductor, may exceed the absolute maximum rating at the maximum loading. Use an inductor with appropriate inductance. Use a diode of a Schottky type with high switching speed, and also pay attention to its current capacity. If the spike noise of Lx pin is too large, make snub circuit (such as serial connection of CR) between Lx and GND, then the noise will be reduced. The time constant of the CR depends on the actual PCB, so evaluate it on the actual PCB. If the load current of the voltage regulator is small, because of the switching noise of DC/DC converter, the output voltage of VOUT2 may be large. To avoid this, use the voltage regulator with a load current at least 0.5mA. In terms of LDO, the difference between the set output voltage and input voltage should be 0.5V or more, 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.
10
R5212D
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
i1 Lx Tr SD L i2 CL IOUT
ILxmin
VOUT
topen
VIN
ton t=1/fosc
toff
Step 1 : Lx Tr. 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 LX Tr. Step 2 : When Lx Tr. 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.
11
R5212D
•
Discontinuous Conduction Mode and Continuous Conduction Mode
The maximum value (ILmax) and the minimum value (ILmin) current which flow through the inductor is the same as those when Lx Tr. turns on and when it turns off. The difference between ILmax and ILmin, which is represented by ∆I; ∆I=ILmax−ILmin=VOUT×topen/L=(VIN−VOUT)×ton/L ........................................................Equation 1 Where, t=1/fosc=ton+toff duty (%)=ton/t×100=ton×fosc×100 topen < toff = In Equation A, VOUT×topen/L and (VIN−VOUT) ×ton/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. In the continuous mode, when Equation 1 is solved for ton and assumed that the solution is tonc tonc=t×VOUT/VIN .............................................................................................................Equation 2 When ton
