CM3718 1.5A LOW-NOISE PWM STEP-DOWN REGULATOR GENERAL DESCRIPTION FEATURES The CM3718 is a low-noise, pulse-width-modulated (PWM), DC-DC step-down converter. It powers logic and transmitters in small wireless systems such as cellular phones, communicating PDAs, and handy-terminals. The device features an internal synchronous rectifier for high efficiency; it requires no external Schottky diode. Excellent noise characteristics and fixed-frequency operation provide easy post-filtering. The CM3718 is ideally suited for Li-lon battery applications. It is also useful for +3V or +5V fixed input applications. Patent Number #6,452,366 1.2MHz switching and synchronization Dynamic output-voltage adjustment from VREF to VIN 1.5A Guaranteed Output Current 95% Efficiency No Schottky Diode Required External Soft Start 8-pin PSOP power packages The device operates in one of four modes. Forced PWM mode operates at a fixed frequency regardless of the load. Shutdown mode places the device in standby, reducing quiescent supply current to under 0.1μA. The CM3718 can deliver over 1.5A. The output voltage can be adjusted from VREF to VIN. The input range is from 2.0V to 5.0V. Other features of the CM3718 include high efficiency, low dropout voltage. It is available in a space-saving 8-pin SOP package. APPLICATIONS Cellular Phone Cordless Phone PDAs and Handy-Terminals CPU I/O Supplies Notebook Chipset Supplies Battery Operated Devices 2006/10/11 Rev. 1.6 PIN CONFIGURATION PSOP-8 (PT-08) Top View 1 VIN 2 GND 3 SD 4 VREF Champion Microelectronic Corporation PVIN 8 LX 7 PGND 6 VFB 5 Page 1 CM3718 1.5A LOW-NOISE PWM STEP-DOWN REGULATOR PIN DESCRIPTION Pin No. CM3718 Symbol Description Min. 1 VIN Voltage supply for internal circuits 2 GND Ground for internal reference voltage divider 3 SD 2 Shutdown level CMOS input level Operating Rating Typ. Max. Enable level 4 VREF VOUT Set Voltage 5 VFB Feedback node for the VOUT 6 PGND Ground for output power transistors 7 LX Inductor connection to the Drains of the internal power MOSFETs 8 PVIN Voltage supply for output power transistors 2.5 5.5 V 0.75 x VIN VIN + 0.3 V 0 2.0 1.1 VIN VREF 2 2.5 5.5 V 5.5 V Part Number Temperature Range Package CM3718IS -40℃ to 85℃ 8-Pin PSOP (PS08) CM3718GIS* -40℃ to 85℃ 8-Pin PSOP (PS08) *Note: G : Suffix for Pb Free Product BLOCK DIAGRAM GND SD PVIN 1 3 8 2 Oscillator Ramp Generator PW M Controller VREF 4 2006/10/11 Rev. 1.6 Error Amp MOS 7 LX Thermal Protection 5 6 VFB PG ND Champion Microelectronic Corporation V V ORDERING INFORMATION VIN1 Uni t Page 2 CM3718 1.5A LOW-NOISE PWM STEP-DOWN REGULATOR ABSOLUTE MAXIMUM RATINGS Absolute maximum ratings are those values beyond which the Junction Temperature ...…………………… …………150°C device could be permanently damaged. Storage Temperature ……................……. -65°C to 125°C PVIN/VIN ………….....................................….......-0.3V to 6.0V Lead Temperature (Soldering, 5 sec)……………….. 260°C Thermal Dissipation(θJC )….. ………………….. .50°C/W Voltage on Any Other Pin ………... GND – 0.3V to VIN + 0.3V Output Current, Source or Sink ……......…………........…...1.5A OPERATING CONDITIONS Temperature Range ............................. -40°C to 85°C PVIN Operating Range .........................2.0V to 4.0V ELECTRICAL CHARACTERISTICS (Unless otherwise stated, these specifications apply TA=25°C; VIN=+3.3V and PVIN=+3.3V) maximum ratings are stress ratings only and functional device operation is not implied. (Note 1) Symbol Parameter CM3718 Test Conditions Min. Typ. Max. Unit SWITCHING REGULATOR VREF Adjustable Output Voltage VREF VIN 1.2 V fsw Switching Frequency CM3718 IOUT(RMS) Maximum Output RMS Current CM3718 1.5 MHz A IOUT(PEAK) Maximum Output Peak Current CM3718 3 A Drain to Source on-State Resistance PVIN=5V MOSFETs RDS(ON) 250 mΩ 220 μA 500 μA SUPPLY IVIN IPVIN 2006/10/11 Rev. 1.6 Quiescent Current VFB = 1.4V LC unconnected VFB = 1.4V LC unconnected Champion Microelectronic Corporation Page 3 CM3718 1.5A LOW-NOISE PWM STEP-DOWN REGULATOR FUNCTIONAL DESCRIPTION The CM3718 step-down, pulse-width-modulated (PWM), INPUTS DC-DC converter has an adjustable output range from VREF The input voltage reference pin, VREF determine the output to the input voltage (VIN). An internal synchronous rectifier voltages (LX). If a specific voltage is forced at the VREF pin, the improves efficiency and eliminates an external Schottky diode. output voltage follows the voltage at the VREF pin. Fixed-frequency operation enables easy post-filtering, thereby providing excellent noise characteristics. As a result, the OTHER SUPPLY VOLTAGES CM3718 is an ideal choice for many small wireless systems. Several inputs are provided for the supply voltages: PVIN and VIN. VREF The PVIN provide the power supply to the power MOSFETs. The reference voltage could be ranged from 1.1V to VIN. VIN provides the voltage supply to the logic section and internal error amplifiers. OUPUTS The output voltage pins (LX) are tied to the RF power amp, FEEDBACK via an external inductor. Output voltage is determined by the The VFB pin is an input that can be used for closed loop VREF inputs. compensation. This input is derived from the voltage output. AGND pin is a contact node of internal resistor divider for remote sense. APPLICATION CIRCUIT NOTE: VDD JP3---->USEING EXTERNAL VOLTAGE SETING BOARD (PIN 1,2 SHORT) C1 100uf/6.3V R4 470 2 5 6 R7 0 U3 VFB PVIN PGND 7 2 8 1 SK12 CM3718-8PIN C6 47uf/6.3V 2 U2 CM-431 1 R5 0 R8 5.1 105 C4 1 2 3 CON3 JP2 C5 104P JP4 2006/10/11 Rev. 1.6 JP3 2 JUMPER VDD 4 1 1 2 3 2 VCC 3 VREF J2 VTT SD 1 VIN C7 104 1 2 C3 470 1 D2 J3 VREF-OUT R1 100k C2 105 L1 3.3uH/2A 2 1 R2 1k 2 LX 3 J1 PWR/IN JP1 JUMPER GND 4 TP1 BNC 1 VCC 1 D1 SK12 2 5 2 1 on/off sw 2 1 R3 100k Champion Microelectronic Corporation Page 4 CM3718 1.5A LOW-NOISE PWM STEP-DOWN REGULATOR LOAD REGULATION Vin=5V, VREF input=1.09V Vin=5V, VREF input=4.04V CM3718 CM3718 5 Vout(V) Vout(V) 2 1 4 8 0. 1 6 4 0. 0. 2 0. 05 0. 1 0.8 0.6 0.4 0.2 0.05 3 0 Iout(A) Iout(A) LOAD TRANSIENT RESPONSE CM3718 Transient Response VREF=1V, (IOUT from 1.5A- 0A) CM3718 Transient Response VREF=1V, (IOUT from 0A- 1.5A) CM3718 Transient Response VREF=4V，(IOUT from 1.5A- 0A) CM3718 Transient Response VREF=4V，(IOUT from 0A- 1.5A) 2006/10/11 Rev. 1.6 Champion Microelectronic Corporation Page 5 CM3718 1.5A LOW-NOISE PWM STEP-DOWN REGULATOR VOUT OUTOUT RIPPLE AND NOISE CM3718 VREF=1V, Load=0.5A CM3718 VREF=1V, Load=1.0A CM3718 VREF=1V, Load=1.5A CM3718 VREF=4V, Load=0.5A CM3718 VREF=4V, Load=1.0A CM3718 VREF=4V, Load=1.5A VOLTAGE SETTING STEP RESPONSE CM3718 (VREF from 1V- 4V), Load=0.5A CM3718 VREF=1V-4V, Load=1.0A CM3718 VREF=1V-4V, Load=1.5A CM3718 VREF=4V-1V, Load=0.5A CM3718 VREF=4V-1V, Load=1.0A CM3718 VREF=4V-1V, Load=1.5A 2006/10/11 Rev. 1.6 Champion Microelectronic Corporation Page 6 CM3718 1.5A LOW-NOISE PWM STEP-DOWN REGULATOR IN-RUSH CURRENT CM3718 Vin=5V, VREF=1V, Load=1.5A, Ip-p=1.81A CM3718 Vin=5V, VREF=4V, Load=1.5A, Ip-p=1.81A EFFICIENCY CM3718 efficiency (VOUT=1V, load from 0.05A~1.5A) CM3718 efficiency (VOUT =4V, load from 0.05A~1.5A) CM3718 CM3718 100.0% 100.0% 98.0% 95.0% 96.0% 94.0% 85.0% Efficiency 80.0% 75.0% 92.0% 90.0% 88.0% 86.0% 70.0% 1.5 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 Iout(A) Iout(A) 2006/10/11 Rev. 1.6 0.2 1.5 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 80.0% 0.05 82.0% 60.0% 0.1 84.0% 65.0% 0.05 Efficiency 90.0% Champion Microelectronic Corporation Page 7 CM3718 1.5A LOW-NOISE PWM STEP-DOWN REGULATOR PCB LAYOUT Top layer Bottom Layer Silkscreen Top Sold-mask Top Sold-mask Bottom 2006/10/11 Rev. 1.6 Champion Microelectronic Corporation Page 8 CM3718 1.5A LOW-NOISE PWM STEP-DOWN REGULATOR PACKAGE DIMENSION 8-PIN PSOP (PS08) θ θ 2006/10/11 Rev. 1.6 Champion Microelectronic Corporation Page 9 CM3718 1.5A LOW-NOISE PWM STEP-DOWN REGULATOR IMPORTANT NOTICE Champion Microelectronic Corporation (CMC) reserves the right to make changes to its products or to discontinue any integrated circuit product or service without notice, and advises its customers to obtain the latest version of relevant information to verify, before placing orders, that the information being relied on is current. A few applications using integrated circuit products may involve potential risks of death, personal injury, or severe property or environmental damage. CMC integrated circuit products are not designed, intended, authorized, or warranted to be suitable for use in life-support applications, devices or systems or other critical applications. Use of CMC products in such applications is understood to be fully at the risk of the customer. In order to minimize risks associated with the customer’s applications, the customer should provide adequate design and operating safeguards. HsinChu Headquarter Sales & Marketing 5F, No. 11, Park Avenue II, Science-Based Industrial Park, HsinChu City, Taiwan 300 7F-6, No.32, Sec. 1, Chenggong Rd., Nangang District, Taipei City 115, Taiwan T E L : +886-3-567 9979 F A X : +886-3-567 9909 http://www.champion-micro.com T E L : +886-2-2788 0558 F A X : +886-2-2788 2985 2006/10/11 Rev. 1.6 Champion Microelectronic Corporation Page 10