SM6702 series PFM Step-up DC/DC Converter NIPPON PRECISION CIRCUITS INC. OVERVIEW The SM6702 series are step-up DC/DC converter ICs, fabricated using NPC’s Molybdenum-gate CMOS process. They incorporate reference voltage source, error amplifier, oscillator, start-up circuit, PFM (Pulse Frequency Modulation) control circuit into a single chip. The only external components required are a Coil, Diode and output smoothing capacitors to form a step-up DC/DC converter. They employ PFM voltage control circuits to achieve high efficiency, stable constant-voltage output. FEATURES ■ ■ ■ ■ ■ ■ Power dissipation : 24 µW at VIN = 1.5 V, VOUT = 3.0 V, IOUT = 100 µA Start-up input voltage : 0.9 V (max) at RL = 30 kΩ Output voltage : 2.2 V to 3.3 V, available in 0.1 Vstep High efficiency : 85% at VIN = 1.5 V, VOUT = 3.0 V, IOUT = 1 mA Low ripple voltage Package : SOT23-3, SOT89-3 APPLICATIONS ■ ■ ■ ■ ■ PDA, Mobile IT equipment Digital Stil Camera Pager Constant-voltage sources for battery-operated equipment Local voltage sources ORDERING INFORMATION D e vice Output voltag e 1 P ackag e SM6702-33HB 3.3 V S O T89-3 SM6702-30HA 3.0 V S O T23-3 SM6702-30HB 3.0 V S O T89-3 SM6702-27HA 2.7 V S O T23-3 SM6702-27HB 2.7 V S O T89-3 SM6702-24HA 2.4 V S O T23-3 1. Stepwise setting with a step of 0.1V in the range of 2.2V to 3.3V is available. NIPPON PRECISION CIRCUITS—1 SM6702 series PINOUT (Top view) SM6702−××HA(SOT23−3) SM6702−××HB(SOT89−3) 0 2 3 2 1 2 1 2 3 PIN DESCRIPTION Number Name S M 6 7 0 2 −××H A S M 6 7 0 2 −××H B 1 1 VSS 2 3 LX 3 2 OUT Description Ground Switching pin Output (device supply pin) PACKAGE DIMENSIONS (Unit : mm) 2.9 ± 0.2 SM6702−××HB(SOT89−3) 4.5 ± 0.1 1.5 ± 0.1 1.55 ± 0.15 0.4 ± 0.1 0.8 ± 0.1 1.1 ± 0.2 0.15 ± 0.1 0.95 0.95 4.0 ± 0.3 2.5 ± 0.1 1.5 1.5 0.2 M 0.05 ± 0.05 (8 ) 0.4 ± 0.1 (5 ) .0 φ1 1.1 ± 0.2 0.2min 2.8 ± 0.2 1.6 ± 0.2 (0.4) 0 to 15 0.1 ± 0.05 (5 ) SM6702−××HA(SOT23−3) 0.37 ± 0.1 (8 ) 0.42 ± 0.1 0.42 ± 0.1 0.47 ± 0.1 NIPPON PRECISION CIRCUITS—2 SM6702 series BLOCK DIAGRAM OUT LX PFM OSC START−UP VREF VSS NIPPON PRECISION CIRCUITS—3 SM6702 series SPECIFICATIONS Absolute Maximum Ratings Ta = 25 °C P arameter Rating Unit V LX 5 V VOUT 4 V LX output current IL X 200 mA Pow er dissipation PD LX impressed voltage OUT impressed voltage Symbol Condition S M 6 7 0 2 −××H A 150 S M 6 7 0 2 −××H B 500 mW Operating temperature T opr − 20 to 70 °C Storage temperature T stg − 40 to 125 °C Electrical Characteristics L = 330 µH, C = 22 µF, Ta = 25 °C, VSS = 0 V Rating P arameter Symbol Condition Unit min typ max Start-up voltage V st R L = 30 k Ω – – 0.9 V Holding voltage V hold R L = 3 kΩ – – 0.7 V IS S V IN = 1.5 V, R L = 30 k Ω – 8 16 µA VOUT V IN = 1.5 V, R L = 3 k Ω V target × 0.975 V target V target × 1.025 V 2.2 ≤ V target ≤ 2.7 60 – – 2.8 ≤ V target ≤ 3.3 80 – – Current consumption Output voltage IL X V O U T = V target − 0.1, V L X = 0.4 V LX leakage current IL X L V O U T = V L X = 3.5 V – – 1 µA M a x i m um oscillator frequency fO S C V O U T = V target − 0.1 80 100 120 kHz Switch ON duty cycle Duty V O U T = V target − 0.1 65 75 85 % Input voltage range V IN – – V target + 0.2 V LX output current mA V target : Setting output voltage NIPPON PRECISION CIRCUITS—4 SM6702 series FUNCTIONAL DESCRIPTION Step-up Principle The SM6702 series use a transistor to switch the input supply in a non-isolated chopper switching regulator configuration. The figure below shows the basic step-up switching regulator circuit. If the transistor is ON for an interval tON and then instantly turned OFF, the energy stored in the coil L during the interval tON generates a voltage VL across the coil. This voltage is superimposed on the input voltage such that the peak voltage reaches VIN + VL which forces the diode D to conduct and release the stored energy into the output. During normal operation, the above switching occurs repeatedly at a frequency controlled by an oscillator (which can change depending on the input and output load conditions), generating a square wave output which is then smoothed by the output capacitor C. Thus the output voltage (VOUT > VIN) has been stepped up. L D VOUT VIN Tr C GND PFM Control In SM6702 series, the LX transistor ON interval is fixed, and the OFF interval varies in response to the input voltage and load changes. Thus the resulting switching cycle frequency varies, called pulse frequency modulation. NIPPON PRECISION CIRCUITS—5 SM6702 series BASIC CIRCUIT L VIN D OUT + LX C OUT VSS Coil (L) : 330 µH Diode (D) : MA721 (Matsushita Schottky diode) Capacitor (C L ) : 22 µF tantalum TYPICAL APPLICATION CIRCUIT L LX + 1.5V C1 D 3V System Voltage OUT C2 + C3 VSS Coil (L) : 330 µH Schottky Diode (D) Capacitor (C1) : 22 µF tantalum Capacitor (C2) : 0.22 µF ceramic Capacitor (C3) : 22 µF tantalum NIPPON PRECISION CIRCUITS—6 SM6702 series BASIC CHARACTERISTICS SM6702-30HA (Vout : 3.0V) Output voltage vs. Output current L=330µH, C=22µF 3.5 Vin=1.5V Output Voltage Vout[V] Output Voltage Vout[V] Vin=0.9V Vin=1.2V 2 1.5 1 Vin=1.5V 3 3 2.5 L=470µH, C=22µF 3.5 0.5 Vin=0.9V 2.5 Vin=1.2V 2 1.5 1 0.5 0 0 5 10 15 20 25 Output Current Iout[mA] 0 30 0 5 10 15 20 25 Output Current Iout[mA] 30 Efficiency vs. Output current L=470µH, C=22µF L=330µH, C=22µF 100 100 95 95 90 90 80 Vin=0.9V Vin=1.5V 75 70 Vin=1.2V Efficiency [%] Efficiency [%] 85 85 80 Vin=0.9V 75 Vin=1.5V 70 65 65 60 60 55 55 Vin=1.2V 50 50 0 5 10 15 20 25 Output Current Iout[mA] 30 0 5 10 15 20 25 30 Output Current Iout[mA] Ripple voltage vs. Output current L=330µH, C=22µF 200 Ripple Voltage Vr[mVpp] 175 150 125 Vin=1.5V 100 Vin=1.2V 75 50 25 Vin=0.9V 0 0 10 20 30 40 50 60 Output Current Iout[mA] NIPPON PRECISION CIRCUITS—7 SM6702 series Output voltage vs. Temperature Vin=1.5V, L=330µH, RL=3kΩ 3.1 3.0 2.9 175 150 125 100 75 50 25 0 2.8 -40 -20 0 20 40 Temperature [°C] 60 -40 80 Start-up voltage vs. Temperature -20 0 20 40 Temperature [°C] 60 80 Hold-on voltage vs. Temperature L=330µH, RL=30kΩ 1.0 L=330µH, RL=3kΩ 1.0 0.8 0.8 Hold-on Voltage Vhold[V] Start-up Voltage Vst[V] Vout=2.9V 200 Maximum Oscillator Frequency fosc[kHz] 3.2 Output Voltage Vout[V] Maximum oscillator frequency vs. Temperature 0.6 0.4 0.2 0.6 0.4 0.2 0.0 -40 -20 0 20 40 Temperature [°C] 60 0.0 80 Current consumption vs. Temperature -40 -20 0 20 40 Temperature [°C] 60 80 Oscillator duty cycle vs. Temperature Vin=1.5V, L=330µH, RL=30kΩ 10 Vout=2.9V 90 Oscillator Duty Cycle [%] Current Consumption Iss[µA] 85 8 6 4 80 75 70 65 60 2 55 50 0 -40 -20 0 20 40 Temperature [°C] 60 80 -40 -20 0 20 40 Temperature [°C] 60 80 NIPPON PRECISION CIRCUITS—8 SM6702 series LX switching current vs. Temperature LX leakage current vs. Temperature Vout=2.9V 200 Vin=Vout=3.5V 100 LX Leakage Current ILXL[nA] LX Switching Current ILX[mA] 175 150 125 100 75 50 10 1 25 0 -40 -20 0 20 40 Temperature [°C] 60 80 0.1 -40 -20 0 20 40 Temperature [°C] 60 80 NIPPON PRECISION CIRCUITS—9 SM6702 series NIPPON PRECISION CIRCUITS INC. reserves the right to make changes to the products described in this data sheet in order to improve the design or performance and to supply the best possible products. Nippon Precision Circuits Inc. assumes no responsibility for the use of any circuits shown in this data sheet, conveys no license under any patent or other rights, and makes no claim that the circuits are free from patent infringement. Applications for any devices shown in this data sheet are for illustration only and Nippon Precision Circuits Inc. makes no claim or warranty that such applications will be suitable for the use specified without further testing or modification. The products described in this data sheet are not intended to use for the apparatus which influence human lives due to the failure or malfunction of the products. Customers are requested to comply with applicable laws and regulations in effect now and hereinafter, including compliance with expor t controls on the distribution or dissemination of the products. Customers shall not expor t, directly or indirectly, any products without first obtaining required licenses and approvals from appropriate government agencies. NIPPON PRECISION CIRCUITS INC. NIPPON PRECISION CIRCUITS INC. 4-3, Fukuzumi 2-chome Koto-ku, Tokyo 135-8430, Japan Telephone: +81-3-3642-6661 Facsimile: +81-3-3642-6698 http://www.npc.co.jp/ Email: sales @ npc.co.jp NC9721CE 2000.10 NIPPON PRECISION CIRCUITS—10