RT34063A. DC/DC Converter Control Circuits. Features. General Description. Applications. Ordering Information. Pin Configurations

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1 DC/DC Converter Control Circuits General Description The RT0A Series is a monolithic control circuit containing the primary functions required for DC/DC converters. These devices consist of an internal temperature compensated reference, comparator, controlled duty cycle oscillator with an active current limit circuit, driver and high current output switch. This series was specially designed to be incorporated in step-down and step-up and Voltage-inverting applications with a minimum number of external components. Ordering Information RT0A Package Type N : DIP- S : SOP- Operating Temperature Range P : Pb Free with Commercial Standard G : Green (Halogen Free with Commercial Standard) Features Operation from.0v to 0V Input Low Standby Current Current Limiting Internal Switch Current to.a Output Voltage Adjustable Frequency Operation to 00kHz Precision % Reference RoHS Compliant and 00% Lead (Pb)-Free Applications Saver for Cellular Phones DC/DC Converter Module Pin Configurations (TOP VIEW) SC DRIVER SE TC GND IPK VCC COMP DIP- / SOP- Note : Richtek Pb-free and Green products are : RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-00. Suitable for use in SnPb or Pb-free soldering processes. 00%matte tin (Sn) plating. Functional Pin Description Pin Name SC SE TC GND COMP VCC IPK DRIVER Pin Function.A Switch Collector. Darling Switch Emitter. Oscillator Timing Capacitor. Power GND. Feedback Comparator Inverting Input. Power Supply Input. High side Current Sense Input VCC-V IPK = 0mV. Driver Collector. DS0A- November 00

2 Function Block Diagram DRIVER SC SQ Q R Q IPK 00 SE VCC IPK CT Oscillator Comparator TC COMP -.V Reference Regulator GND Typical Application Circuit L 0µH 0 S Q R N9 V R SC 0. 00µF I PK C T OSC - COMP.V Ref C T 00pF R.K R K 0µF V/mA C O Optional Filter.0µH 00µF Figure. Step-up Converter DS0A- November 00

3 (a) External NPN Switch R R 0 for Constant VIN (b) External NPN Saturated Switch (See Note) Figure. External Current Boost Connections for I C Peak Greater than.a Note: If the output switch is driven into hard saturation (non-darling configuration) at low switch currents ( 00mA) and high driver currents ( 0mA), it may take up to.0μs to come out of saturation. This condition will shorten the off time at frequencies 0kHz, and is magnified at high temperature. This condition does not occur with a Darling configuration, since the output switch cannot saturate. If a non-darling configuration is used, the following output drive condition is recommended. DS0A- November 00

4 S Q Q R Q N9 V R SC 0. 00µF I PK C T OSC - COMP.V Ref C T 0pF L 0µH R.K R.K 0µF C O.0V/00mA Optional Filter.0µH 00µF Figure. Step-down Converter DS0A- November 00

5 (a) External NPN Switch (b) External PNP Saturated Switch Figure. External Current Boost Connections for I C Peak Greater than.a DS0A- November 00

6 0 S Q Q R Q.V to.0v R SC 0. 00µF I PK C T OSC - COMP.V Ref µh L N9 00pF R.K R 9 000µF -V/00mA C O Optional Filter.0µH 00µF Figure. Voltage Inverting Converter DS0A- November 00

7 (a) External NPN Switch (b) External PNP Saturated Switch Figure. External Current Boost Connections for Peak Greater than.a DS0A- November 00

8 Design Formula Table Calculation Step-up Step-down Voltage-Inverting t on /t off VOUT V V F IN(MIN) V V IN (MIN) SAT V IN(MIN) VOUT VF VSAT V OUT V V OUT IN V V SAT F (t on t off ) f f f t off toff toff toff toff toff toff t on ( toff) toff ( toff) toff ( toff) toff C T Ipk (SWITCH) IOUT (MAX) IOUT (MAX) IOUT(MAX) toff toff R SC 0./Ipk (SWITCH) 0./Ipk (SWITCH) 0./Ipk (SWITCH) L (min) ( VIN(MIN) VSAT) ( VIN(MIN) VSAT) ( VIN(MIN) VSAT) Ipk (SWITCH) t on(max) Ipk (SWITCH) t on(max) Ipk (SWITCH) t on(max) C O IOUT 9 Vripple (pp) I pk(switch) ( V ripple(pp) t off ) IOUT 9 Vripple (pp) V SAT : Saturation voltage of the output switch. V F : Forward voltage drop of the output rectifier. The following power supply characteristics must be chosen: : Nominal input voltage. : Desired output voltage I OUT : Desired output current. R =.( ) R f : Minimum desired output switching frequency at the selected values of Vin and I O. V ripple(pp) : Desired peak-to-peak output ripple voltage. In practice, the calculated capacitor value needs to be increased due to its equivalent series resistance and board layout. The ripple voltage should be kept to a low value since it directly affects the line and load regulation. DS0A- November 00

9 Absolute Maximum Ratings (Note ) Power Supply Voltage V Feedback Input Voltage Range to 0V Switch Collector Voltage V Switch Emitter Voltage V Switch Collector to Emitter Voltage V Driver Collector Voltage V Driver Collector Current (see Note) mA Switch Current A Power Dissipation, P T A = C DIP W SOP W Package Thermal Resistance (Note ) DIP-, θ JA C/W SOP-, θ JA C/W Junction Temperature C Storage Temperature Range to 0 C Note:Maximum package power dissipation limits must be observed. Recommended Operating Conditions (Note ) Power Supply Input Voltage Range V to 0V Junction Temperature Range C to C Ambient Temperature Range C to C Electrical Characteristics (VCC = V, TA = C, unless otherwise specified) Parameter Symbol Test Conditions Min Typ Max Unit Oscillator Frequency VPIN = 0V, CT =.0nF khz Charge Current I CHG.0V VCC 0V μa Discharge Current I DISCHG.0V VCC 0V μa Discharge to Charge Current Ratio Pin to VCC Current Limit Sense Voltage V LIM I CHG = I DISCHG mv Output Switch Saturation Voltage, Darling Connection Saturation Voltage, Darling Connection I SW =.0A, Pins, connected V I SW =.0A, R PIN = Ω to VCC, Forced β V DC Current Gain ISW =.0A, VCE =.0V Collector Off-state Current VCE = 0V μa To be continued DS0A- November 00 9

10 Comparator Parameter Symbol Test Conditions Min Typ Max Unit Threshold Voltage... V Threshold Voltage Line Regulation.0V VCC 0V mv Input Bias Current I BIAS VIN = 0V na Total Device Supply Current I CC VCC =.0V to 0V, C T =.0nF, Pin = VCC, V PIN > V TH, Pin = GND, Remaining pins open ma Note. Stresses listed as the above Absolute Maximum Ratings may cause permanent damage to the device. These are for stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may remain possibility to affect device reliability. Note. θja is measured in the natural convection at TA = C on a low effective thermal conductivity test board of JEDEC - thermal measurement standard. Note. The device is not guaranteed to function outside its operating conditions. 0 DS0A- November 00

11 Typical Operating Characteristics TOn-Off, Output Switch On-Off Time (us) 000 VCE, Saturation Voltage (V) A ICC, Supply Current (ma) Output Switch On-Off Time vs. Oscillator Timing Capacitor VCC =.0V Pin = VCC Pin = GND TA = C TC, Oscilator Timing Capacitor (nf) Emitter Follower Configuration Output Saturation Voltage vs. Emiter Current Standyby Supply Current vs. Supply Voltage Supply Voltage (V) DS0A- November 00 VCC =.0V Pin,, = VCC Pin, = GND TA = C IE, Emitter Current (A) VCC =.0V Pin = VCC Pin =.0V Pin = GND TA = C VCE, Saturation Voltage (V) A Current Limit Sense Voltage (mv). Timing Capacitor Waveform VOUT =.0V Pin, = Open, Pin = VCC CT =.0nF,Pin = GND TA = C Time (0μs/Div) Common Emiter Configuration Output Switch Saturation Voltage vs. Collector Current Current Limit Sense Voltage vs. Temperature ICC, Collector Current (A) VCC =.0V Pin = VCC Pin,, = GND TA = C VCC =.0V ICHARGE = IDISCHARGE Temperature ( C)

12 I C vs. V CE(Q) Curve I C vs. V CE(Q) Curve 000 TJ = -0 C Ib = ma 000 TJ = -0 C Ib = ma IC (ma) Ib = ma Ib = ma IC (ma) Ib = ma Ib = ma Ib =.ma Ib =.ma V CE (mv) V CE (mv) I C vs. V CE(Q) Curve I C vs. V CE(Q) Curve 000 TJ = 0 C Ib = ma 000 TJ = C Ib = ma IC (ma) Ib = ma Ib = ma IC (ma) Ib = ma Ib = ma 00 Ib =.ma 00 Ib=.mA V CE (mv) V CE (mv) TJ = 0 C I C vs. V CE(Q) Curve Ib = ma Ib = ma IC (ma) Ib = ma Ib =.ma V CE (mv) DS0A- November 00

13 Outline Dimension A B E J C L I D F Symbol Dimensions In Millimeters Dimensions In Inches Min Max Min Max A B C D E F I J L Lead DIP Plastic Package DS0A- November 00

14 A H M J B F I C D Symbol Dimensions In Millimeters Dimensions In Inches Min Max Min Max A B C D F H I J M Lead SOP Plastic Package Richtek Technology Corporation Headquarter F, No. 0, Taiyuen Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: ()9 Fax: () Richtek Technology Corporation Taipei Office (Marketing) F, No., Lane, Paochiao Road, Hsintien City Taipei County, Taiwan, R.O.C. Tel: ()99 Fax: ()99 marketing@richtek.com Information that is provided by Richtek Technology Corporation is believed to be accurate and reliable. Richtek reserves the right to make any change in circuit design, specification or other related things if necessary without notice at any time. No third party intellectual property infringement of the applications should be guaranteed by users when integrating Richtek products into any application. No legal responsibility for any said applications is assumed by Richtek. DS0A- November 00