CM3718C 1.5A LOW-NOISE PWM STEP-DOWN REGULATOR GENERAL DESCRIPTION FEATURES The CM3718C 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 CM3718C is ideally suited for Li-lon battery applications. It is also useful for +3V or +5V fixed input applications. 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. Patented Filed #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 SOP package. 24 Hours Technical Support---WebSIM Champion provides customers an online circuit simulation tool called WebSIM. You could simply logon our website at The CM3718C 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 CM3718C include high efficiency, low dropout voltage. It is available in a space-saving 8-pin SOP package. www.champion-micro.com for details. APPLICATIONS PIN CONFIGURATION SOP-8 (S08) Top View Cellular Phone Cordless Phone PDAs and Handy-Terminals CPU I/O Supplies Notebook Chipset Supplies Battery Operated Devices 2005/02/02 1 VIN 2 GND 3 SD 4 VREF Champion Microelectronic Corporation PVIN 8 LX 7 PGND 6 VFB 5 Page 1 CM3718C 1.5A LOW-NOISE PWM STEP-DOWN REGULATOR PIN DESCRIPTION Pin No. Symbol Description Min. 1 VIN Voltage supply for internal circuits 2 GND Ground for internal reference voltage divider 3 SD CMOS input level Operating Rating Typ. Max. 2 Shutdown level 5.5 V 0.75 x VIN VIN + 0.3 V 0 2.0 1.1 VIN 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 VREF 2 2.5 Part Number Temperature Range Package CM3718CIS -40℃ to 85℃ 8-Pin SOP (S08) 5.5 V 5.5 V CM3718CGIS* -40℃ to 85℃ 8-Pin SOP (S08) *Note: G : Suffix for Pb Free Product BLOCK DIAGRAM VIN1 SD PVIN 1 3 8 2 Oscillator Ramp Generator PW M Controller VREF 2005/02/02 4 Error Amp MOS 7 LX Thermal Protection 5 6 VFB PG ND Champion Microelectronic Corporation V V ORDERING INFORMATION GND Uni t Page 2 CM3718C 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 Test Conditions CM3718C Min. Typ. Max. Unit SWITCHING REGULATOR VREF Adjustable Output Voltage VREF VIN 1.2 V fsw Switching Frequency CM3718C IOUT(RMS) Maximum Output RMS Current CM3718C 1.5 MHz A IOUT(PEAK) Maximum Output Peak Current CM3718C 3 A Drain to Source on-State Resistance PVIN=5V MOSFETs RDS(ON) 250 mΩ 220 µA 500 µA SUPPLY IVIN IPVIN 2005/02/02 Quiescent Current VFB = 1.4V LC unconnected VFB = 1.4V LC unconnected Champion Microelectronic Corporation Page 3 CM3718C 1.5A LOW-NOISE PWM STEP-DOWN REGULATOR FUNCTIONAL DESCRIPTION The CM3718C 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 CM3718C 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 6 5 VFB PVIN PGND 7 8 2 R7 0 U3 CM3718-8PIN C6 47uf/6.3V 2 U2 CM-431 3 1 R5 0 R8 5.1 105 C4 JP3 1 2 3 2 JUMPER VDD 4 1 1 2 3 2 VREF VIN VCC SD 1 J2 VTT CON3 JP2 C5 104P JP4 2005/02/02 R4 470 2 1 SK12 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 CM3718C 1.5A LOW-NOISE PWM STEP-DOWN REGULATOR PACKAGE DIMENSION 8-PIN SOP (S08) PIN 1 ID θ θ 2005/02/02 Champion Microelectronic Corporation Page 5 CM3718C 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 11F, No. 306-3, Sec. 1, Ta Tung Rd., Hsichih, Taipei Hsien, Taiwan 221 T E L : +886-3-567 9979 F A X : +886-3-567 9909 http://www.champion-micro.com T E L : +886-2-8692 1591 F A X : +886-2-8692 1596 2005/02/02 Champion Microelectronic Corporation Page 6