CM3718

CM3718 1.5A LOW-NOISE PWM STEP-DOWN REGULATOR GENERAL DESCRIPTION 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. 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. FEATURES 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 APPLICATIONS Cellular Phone Cordless Phone PDAs and Handy-Terminals CPU I/O Supplies Notebook Chipset Supplies Battery Operated Devices PIN CONFIGURATION PSOP-8 (PT-08) Top View 1 2 3 4 VIN GND SD VREF PVIN LX PGND VFB 8 7 6 5 2006/10/11 Rev. 1.6 Champion Microelectronic Corporation Page 1 CM3718 1.5A LOW-NOISE PWM STEP-DOWN REGULATOR PIN DESCRIPTION Pin No. CM3718 Symbol Description Min. Operating Rating Typ. Max. Uni t 1 2 3 VIN GND SD Voltage supply for internal circuits Ground for internal reference voltage divider CMOS input level VOUT Set Voltage Feedback node for the VOUT Ground for output power transistors Inductor connection to the Drains of the internal power MOSFETs Voltage supply for output power transistors Shutdown level Enable level 2 2.5 5.5 V 0.75 x VIN 0 1.1 VREF VIN + 0.3 2.0 VIN V 4 5 6 7 8 VREF VFB PGND LX PVIN V V 5.5 2 2.5 5.5 V V ORDERING INFORMATION Part Number Temperature Range Package CM3718IS CM3718GIS* -40℃ to 85℃ -40℃ to 85℃ 8-Pin PSOP (PS08) 8-Pin PSOP (PS08) *Note: G : Suffix for Pb Free Product BLOCK DIAGRAM VIN1 1 SD 3 PVIN 8 GND 2 Oscillator Ramp Generator P W M Controller Thermal Protection MOS 7 LX VREF 4 Error Amp 5 VFB 6 PG ND 2006/10/11 Rev. 1.6 Champion Microelectronic Corporation Page 2 CM3718 1.5A LOW-NOISE PWM STEP-DOWN REGULATOR ABSOLUTE MAXIMUM RATINGS Absolute maximum ratings are those values beyond which the device could be permanently damaged. PVIN/VIN ………….....................................….......-0.3V to 6.0V Voltage on Any Other Pin ………... GND – 0.3V to VIN + 0.3V Output Current, Source or Sink ……......…………........…...1.5A Junction Temperature ...…………………… …………150°C Storage Temperature ……................……. -65°C to 125°C Lead Temperature (Soldering, 5 sec)……………….. 260°C Thermal Dissipation(θJC )….. ………………….. .50°C/W 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 SWITCHING REGULATOR Parameter Test Conditions CM3718 Min. Typ. Max. Unit VREF fsw IOUT(RMS) IOUT(PEAK) MOSFETs Adjustable Output Voltage Switching Frequency Maximum Output RMS Current Maximum Output Peak Current Drain to Source on-State Resistance CM3718 CM3718 CM3718 PVIN=5V VFB = 1.4V LC unconnected VFB = 1.4V LC unconnected VREF 1.2 VIN 1.5 3 250 V MHz A A mΩ RDS(ON) SUPPLY IVIN IPVIN Quiescent Current 220 500 μA μA 2006/10/11 Rev. 1.6 Champion Microelectronic Corporation Page 3 CM3718 1.5A LOW-NOISE PWM STEP-DOWN REGULATOR FUNCTIONAL DESCRIPTION The CM3718 step-down, pulse-width-modulated (PWM), DC-DC converter has an adjustable output range from VREF to the input voltage (VIN). An internal synchronous rectifier Fixed-frequency operation enables easy post-filtering, thereby providing excellent noise characteristics. As a result, the CM3718 is an ideal choice for many small wireless systems. INPUTS The input voltage reference pin, VREF determine the output 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. OTHER SUPPLY VOLTAGES Several inputs are provided for the supply voltages: PVIN and VIN. The PVIN provide the power supply to the power MOSFETs. VIN provides the voltage supply to the logic section and internal error amplifiers. VREF The reference voltage could be ranged from 1.1V to VIN. OUPUTS The output voltage pins (LX) are tied to the RF power amp, via an external inductor. Output voltage is determined by the VREF inputs. FEEDBACK The VFB pin is an input that can be used for closed loop 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: JP3---->USEING EXTERNAL VOLTAGE SETING BOARD (PIN 1,2 SHORT) 1 D1 SK12 JP1 JUMPER C2 105 1 L1 3.3uH/2A 2 D2 SK12 2 1 J2 VTT 1 2 J3 VREF-OUT R5 0 C7 104 C6 47uf/6.3V VREF GND VIN SD 2 R1 100k 2 C3 470 2 1 8 7 6 5 U3 CM3718-8PIN 2 U2 CM-431 1 VCC 3 R7 0 R2 1k 1 R4 470 VCC VDD 2 1 J1 PWR/IN C1 100uf/6.3V 5 4 3 TP1 BNC 1 LX PGND PVIN VFB 1 2 3 1 R8 5.1 JUMPER VDD JP2 2 105 C4 4 JP3 1 2 3 CON3 C5 104P 2 R3 100k 1 JP4 on/off sw 2006/10/11 Rev. 1.6 Champion Microelectronic Corporation 2 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 2 Vout(V) Vout(V) 4 1 3 0.05 0.2 0.4 0.6 0 2 4 6 05 0. 0. 0. 0. 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 0. Iout(A) 8 Champion Microelectronic Corporation 1 0.8 1 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 CM3718 efficiency (VOUT =4V, load from 0.05A~1.5A) CM3718 100.0% 95.0% 90.0% Efficiency Efficiency 85.0% 80.0% 75.0% 70.0% 65.0% 60.0% 0.05 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.5 100.0% 98.0% 96.0% 94.0% 92.0% 90.0% 88.0% 86.0% 84.0% 82.0% 80.0% 0.05 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.5 Iout(A) Iout(A) 2006/10/11 Rev. 1.6 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 5F, No. 11, Park Avenue II, Science-Based Industrial Park, HsinChu City, Taiwan 300 T E L : +886-3-567 9979 F A X : +886-3-567 9909 http://www.champion-micro.com Sales & Marketing 7F-6, No.32, Sec. 1, Chenggong Rd., Nangang District, Taipei City 115, Taiwan 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