CM3718C CM3718CIS CM3718-8PIN CM-431

1.5A LOW-NOISE PWM STEP-DOWN REGULATOR GENERAL DESCRIPTION FEATURES The CM3718C is a low-noise, pulse-width-modulated (PWM),

CM3718C CM3718C 1.5A LOW-NOISE PWM STEP-DOWN REGULATOR GENERAL DESCRIPTION FEATURES The CM3718C 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 CM3718C is ideally suited for Li-lon battery applications. It is also useful for +3V or +5V fixed input applications. ! 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. 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. 24 Hours Technical Support-WebSIM Champion provides customers an online circuit simulation tool called WebSIM. You could simply logon our website at The CM3718C 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 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 ! ! Cordless Phone ! PDAs and Handy-Terminals ! CPU I/O Supplies ! Notebook Chipset Supplies ! Battery Operated Devices SOP-8 (S08) Top View Cellular Phone VIN 2 GND 3 SD 4 2002/11/14 1 VREF Champion Microelectronic Corporation PVIN 8 LX 7 PGND 6 VFB 5 Page 1 CM3718C CM3718C 1.5A LOW-NOISE PWM STEP-DOWN REGULATOR PIN DESCRIPTION Pin No. Symbol Description Operating Rating Typ. Max. Unit Min. 1 VIN Voltage supply for internal circuits 2 2 GND Ground for internal reference voltage divider 3 SD Shutdown active high. CMOS input level 5 VFB PGND LX PVIN Voltage supply for output power transistors VIN Inductor connection to the Drains of the internal power MOSFETs 8 0.3V Ground for output power transistors 7 V Feedback node for the VOUT 6 VIN + 1.1 VOUT Set Voltage V VIN VREF 5 0.75 x 4 2.5 VREF V 5 2 2.5 V 5 V ORDERING INFORMATION Part Number Temperature Range Package CM3718CIS CM3718CIS -40 to 85 8-Pin SOP (S08) BLOCK DIAGRAM VIN1 PVIN 1 G ND SD 3 8 2 O scillator Ramp G enerator PW M Controller VREF 4 Error Amp 5 VFB 2002/11/14 MO S 7 LX Therm al Protection 6 PG ND Champion Microelectronic Corporation V Page 2 CM3718C 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 PVIN/VIN .-0.3V to 5.0V Lead Temperature (Soldering, 5 sec). 260°C Thermal Dissipation ( JC ). . .50°C/W Voltage on Any Other Pin . GND 0.3V to VIN + 0.3V . -65°C to 125°C 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 CM3718C Min. Typ. Max. Unit SWITCHING REGULATOR VREF Adjustable Output Voltage VREF VIN 1.2 V fsw Switching Frequency CM3718C CM3718C IOUT(RMS) Maximum Output RMS Current CM3718C CM3718C 1.5 MHz A IOUT(PEAK) Maximum Output Peak Current CM3718C CM3718C 3 A Drain to Source on-State Resistance PVIN=5V MOSFETs RDS(ON) 250 m 220 µA 500 µA SUPPLY IVIN IPVIN 2002/11/14 Quiescent Current VFB = 1.4V LC unconnected VFB = 1.4V LC unconnected Champion Microelectronic Corporation Page 3 CM3718C CM3718C 1.5A LOW-NOISE PWM STEP-DOWN REGULATOR FUNCTIONAL DESCRIPTION The CM3718C 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 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 5 2 1 4 VCC 1 D1 SK12 J1 PWR/IN JP1 JUMPER R2 1k 2 TP1 BNC 1 R1 100k C2 105 C3 470 1 3 L1 3.3uH/2A 5 R7 0 U3 VFB 6 PGND 7 PVIN LX 8 2 SK12 C7 104 R4 470 2 1 D2 2 1 1 2 CM3718-8PIN CM3718-8PIN 2 C6 47uf/6.3V U2 CM-431 CM-431 105 C4 R8 5.1 4 2 1 R5 0 3 2 1 1 2 J3 VREF-OUT 3 VREF VCC SD VIN J2 VTT GND 1 JP3 1 2 3 2 JUMPER CON3 VDD JP2 C5 104P 2 1 R3 100k JP4 2002/11/14 on/off sw Champion Microelectronic Corporation Page 4 CM3718C CM3718C 1.5A LOW-NOISE PWM STEP-DOWN REGULATOR PACKAGE DIMENSION 8-PIN SOP (S08) PIN 1 ID 2002/11/14 Champion Microelectronic Corporation Page 5 CM3718C 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. CMC products in such applications is understood to be fully at the risk of the customer. Use of 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 2002/11/14 Champion Microelectronic Corporation Page 6