CM3706 CHAMP | Alldatasheet

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1.5MHz, 600mA Synchronous Step-Down Regulator 2006/12/20Rev. 1.6 Champion Microelectronic Corporation Page 1 GENERAL DESCRIPTION

FEATURES

The CM3706 is a 1.5MHz constant frequency, slope compensated current mode PWM step-down converter. The device integrates a main switch and a synchronous rectifier for high efficiency without an external Schottky diode. It is ideal for powering portable equipment that runs from a single cell lithium-Ion (Li+) battery. The CM3706 can supply 600mA of load current from a 2.5V to 5.5V input voltage. The output voltage can be regulated as low as 0.6V. The CM3706 can also run at 100% duty cycle for low dropout operation, extending battery life in portable system. Idle mode operation at light loads provides very low output ripple voltage for noise sensitive applications. The CM3706 is offered in a low profile (1mm) 5-pin, thin TSOT package, and is available in an adjustable version. High Efficiency: Up to 96% 1.5Mhz Constant Switching Frequency 600mA Output Current at V IN=3V Integrated Main switch and synchronous rectifier. No Schottky Diode Required 2.5V to 5.5V Input Voltage Range Output Voltage as Low as 0.6 V 100% Duty Cycle in Dropout Low Quiescent Current: 300µA Slope Compensated Current Mode Control for Excellent Line and Load Transient Response Short Circuit Protection Thermal Fault Protection <1uA Shutdown Current Space Saving 5-Pin Thin TSOT23 package

APPLICATIONS

‹ Cellular and Smart Phones ‹ Microprocessors and DSP Core Supplies ‹ Wireless and DSL Modems ‹ PDAs ‹ MP3 Players ‹ Portable Instruments ‹ Digital Still and Video Cameras TYPICAL APPLICATIONS VIN SW CM3706 RUN GND V FB 2.5V TO 5.5V Cin 4.7uF Cout 10uF 22PF 634k 2.2uH 316K OUT IN Figure 1. Basic Application Circuit with CM3706 adjustable version

1.5MHz, 600mA Synchronous Step-Down Regulator 2006/12/20Rev. 1.6 Champion Microelectronic Corporation Page 2 PIN CONFIGURATION TSOT23-5 Top View RUN FB SW VIN GND BLOCK DIAGRAM

1.5MHz, 600mA Synchronous Step-Down Regulator 2006/12/20Rev. 1.6 Champion Microelectronic Corporation Page 3 PIN DESCRIPTION Pin No. Symbol

Description

Regulator Enable control input. Drive RUN above 1.5V to turn on the part. Drive RUN below 0.3V to turn it off. In shutdown, all functions are disabled drawing <1µA supply current. Do not leave RUN floating. GND Ground Pin. SW Power Switch Output. It is the Switch note connection to Inductor. This pin connects to the drains of the internal P-CH and N-CH MOSFET switches. VIN Supply Input Pin. Must be closely decoupled to GND, Pin 2, with a 2.2µF or greater ceramic capacitor. FB VFB (CM3706): Feedback Input Pin. Connect FB to the center point of the external resistor divider. The feedback threshold voltage is 0.6V.

ORDERING INFORMATION

-40 to +85 TSOT23-5 CM3706GIM25 Adj -40 to +85 TSOT23-5 CM3706 X X X ABSOLUTE MAXIMUM RATINGS(Note 1) Absolute maximum ratings are those values beyond which the device could be permanently damaged. OPERATING CONDITIONS Lead Free Suffix for Temperature Package I : -40 to +85 M25 : TSOT23-5 Blank : Normal G: Lead Free Package

1.5MHz, 600mA Synchronous Step-Down Regulator 2006/12/20Rev. 1.6 Champion Microelectronic Corporation Page 4 Thermal Resistance (Note 3): Package ӨJA ӨJC TSOT23-5 250°C/W 110°C/W Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: TJ is calculated from the ambient temperature TA and power dissipation PD according to the following formula: CM3706: TJ = TA + (PD)╳(ӨJA) Note 3: Thermal Resistance is specified with approximately 1 square of 1 oz copper. ELECTRICAL CHARACTERISTICS (Unless otherwise stated, these specifications apply TA=25°C; VIN=+3.6V) maximum ratings are stress ratings only and functional device operation is not implied. Parameter Conditions MIN TYP MAX unit Input Voltage Range 2.5 5.5 V VFB=0.5V 270 400 µA Input DC Supply Current Active Mode Shutdown Mode VFB=0V, VIN=4.2V 0.08 1.0 µA TA = +25°C 0.5880 0.6000 0.6120 V TA= 0°C ≤ TA ≤ 85°C 0.5865 0.6000 0.6135 V Regulated Feedback Voltage TA= -40°C ≤ TA ≤ 85°C 0.5850 0.6000 0.6150 V VFB Input Bias Current VFB = 0.65V ±30 nA Reference Voltage Line Regulation VIN = 2.5V to 5.5V, 0.11 0.4 %/V 1.164 1.200 1.236 V 1.455 1.500 1.545 V Regulated Output Voltage 1.746 1.800 1.854 V Output Voltage Line Regulation VIN = 2.5V to 5.5V,IOUT=10mA 0.11 0.40 %/V Output Voltage Load Regulation IOUT from 10 to 600mA 0.0015 %/mA Peak Inductor Current VIN=3V, VFB=0.5V or VOUT=90% Duty Cycle <35% 1.2 A Oscillator Frequency VFB=0.6V or VOUT=100% 1.2 1.5 1.8 MHz RDS(ON) of P-CH MOSFET ISW = 300mA 0.3 0.50 Ω RDS(ON) of N-CH MOSFET ISW = -300mA 0.2 0.45 Ω SW Leakage VRUN = 0V, VSW= 0V or 5V, VIN = 5V ±0.01 µA RUN Threshold -40°C ≤ TA ≤ 85°C 0.3 0.45 1.5 V RUN Leakage Current ±0.1 µA Thermal Shutdown Trip Threshold 150 Output over voltage lockout ∆VOVL = VOVL – VFB mV Note 4: 100% production test at +25°C. Specifications over the temperature range are guaranteed by design and characterization.

1.5MHz, 600mA Synchronous Step-Down Regulator 2006/12/20Rev. 1.6 Champion Microelectronic Corporation Page 5 FUNCTIONAL DESCRIPTION Operation CM3706 is a monolithic switching mode Step-Down DC-DC converter. It utilizes internal MOSFETs to achieve high efficiency and can generate very low output voltage by using internal reference at 0.6V. It operates at a fixed switching frequency, and uses the slope compensated current mode architecture. This Step-Down DC-DC Converter supplies 600mA output current at VIN = 3V with input voltage range from 2.5V to 5.5V. Current Mode PWM Control Slope compensated current mode PWM control provides stable switching and cycle-by-cycle current limit for excellent load and line responses and protection of the internal main switch (P-Ch MOSFET) and synchronous rectifier (N-CH MOSFET). During normal operation, the internal P-Ch MOSFET is turned on for a certain time to ramp the inductor current at each rising edge of the internal oscillator, and switched off when the peak inductor current is above the error voltage. The current comparator, ICOMP, limits the peak inductor current. When the main switch is off, the synchronous rectifier will be turned on immediately and stay on until either the inductor current starts to reverse, as indicated by the current reversal comparator, IZERO, or the beginning of the next clock cycle. The OVDET comparator controls output transient overshoots by turning the main switch off and keeping it off until the fault is no longer present. Dropout Operation When the input voltage decreases toward the value of the output voltage, the CM3706 allows the main switch to remain on for more than one switching cycle and increases the duty cycle (Note 5) until it reaches 100%. The output voltage then is the input voltage minus the voltage drop across the main switch and the inductor. At low input supply voltage, the RDS(ON) of the P-Channel MOSFET increases, and the efficiency of the converter decreases. Caution must be exercised to ensure the heat dissipated not to exceed the maximum junction temperature of the IC. Idle Mode Operation At very light loads, the CM3706 automatically enters Idle Mode. In the Idle Mode, the inductor current may reach zero or reverse on each pulse. The PWM control loop will automatically skip pulses to maintain output regulation. The bottom MOSFET is turned off by the current reversal comparator, IZERO, and the switch voltage will ring. This is discontinuous mode operation, and is normal behavior for the switching regulator. Maximum Load Current The CM3706 will operate with input supply voltage as low as 2.5V, however, the maximum load current decreases at lower input due to large IR drop on the main switch and synchronous rectifier. The slope compensation signal reduces the peak inductor current as a function of the duty cycle to prevent sub-harmonic oscillations at duty cycles greater than 50%. Conversely the current limit increases as the duty cycle decreases. Note 5: The duty cycle D of a step-down converter is defined as: 100 100 IN OUT OSC ON V V f T D where TON is the main switch on time, and fOSC is the oscillator frequency (1.5Mhz).

1.5MHz, 600mA Synchronous Step-Down Regulator 2006/12/20Rev. 1.6 Champion Microelectronic Corporation Page 6 Typical Performance Characteristics (Test Figure 1 above unless otherwise specified)

1.5MHz, 600mA Synchronous Step-Down Regulator 2006/12/20Rev. 1.6 Champion Microelectronic Corporation Page 7 Output Voltage vs Temperature TEMPERATURE (℃) OUTPUT VOLTAGE (V) 1.17 1.18 1.19 1.2 1.21 1.22 1.23 -40 -30 -20 -10 20 30 40 50 60 Vin=5V Vout=1.2V ILoad=600mA Pulse Skipping Mode Operation SW 1V/DIV ILoad 20mA/DIV Vin=3.6V Vout=1.8V Iload=10.29mA 1 u s Discontinuous Operation SW 1V/DIV ILoad 20mA/DIV Vin=3.6V Vout=1.8V Iload=22.24mA 0.2 u s Start-Up from shutdown Vout 0.5V/DIV ILoad 200mA/DIV Vin=3.6V Vout=1.2V Iloa d=600mA 0.5ms Load step Vout 20mV/DIV ILoad 0.2A/DIV Vin=5V Vout=2.5V ILOAD=0mA TO 600mA 200us Load step Vout 20mV/DIV ILoad 0.2A/DIV Vin=5V Vout=2.5V ILOAD=50mA TO 600mA 200us Load step Vout 20mV/DIV ILoad 0.2A/DIV Vin=5V Vout=2.5V ILOAD=100mA TO 600mA 500us

1.5MHz, 600mA Synchronous Step-Down Regulator 2006/12/20Rev. 1.6 Champion Microelectronic Corporation Page 8 APPLICATIONS INFORMATION Setting the Output Voltage Figure 2 above shows the basic application circuit with CM3706 adjustable output version. The external resistor sets the output voltage according to the following equation: 6.0 R R V VOUT R1=316KΩ ; R2= 316KΩ ; VOUT =1.2V R1=316KΩ ; R2= 470KΩ ; VOUT =1.5V R1=316KΩ ; R2= 630KΩ ; VOUT =1.8V R1=316KΩ ; R2= 1MΩ ; VOUT =2.5V R1=316KΩ ; R2= 1.42MΩ ; VOUT =3.3V. Input Capacitor Selection The input capacitor reduces the surge current drawn from the input and switching noise from the device. The input capacitor impedance at the switching frequency shall be less than input source impedance to prevent high frequency switching current passing to the input. A low ESR input capacitor sized for maximum RMS current must be used Ceramic capacitors with X5R or X7R dielectrics are highly recommended because of their low ESR and small temperature coefficients. A 4.7µF ceramic capacitor for most applications is sufficient. Inductor Selection For most designs, the CM3706 operates with inductors of 1µH to 4.7µH. Low inductance values are physically smaller but require faster switching, which results in some efficiency loss. The inductor value can be derived from the following equation: OSC L IN OUT IN OUT f I V V V V L Where LI is inductor Ripple Current. Large value inductors lower ripple current and small value inductors result in high ripple currents. Choose inductor ripple current approximately 35% of the maximum load current 600mA, or LI =210mA. VIN SW CM3706 RUN GND V FB 2.5V TO 5.5V Cin 4.7uF Cout 10uF 22PF 634k 2.2uH 316K OUT IN Figure2 Application Circuit with adjustable output versions For output voltages above 2.0V, when light-load efficiency is important, the minimum recommended inductor is 2.2µH. For optimum voltage-positioning load transients, choose an inductor with DC series resistance in the 50mΩ to 150mΩ range. For higher efficiency at heavy loads, or minimal load regulation (but some transient overshoot), the resistance should be kept below 100mΩ. The DC current rating of the inductor should be at least equal to the maximum load current plus half the ripple current to prevent core saturation (600mA+105mA). Output Capacitor Selection The output capacitor is required to keep the output voltage ripple small and to ensure regulation loop stability. The output capacitor must have low impedance at the switching frequency. Ceramic capacitors with X5R or X7R dielectrics are recommended due to their low ESR and high ripple current.The output ripple VOUT is determined by: C f ESR L f V V V V V osc OSC IN OUT IN OUT OUT Input Zener Selection In USB device application, we will add zener. The zener can be reduced the surge voltage when device plug in and plug out. Application circuit is show in Figure3.

1.5MHz, 600mA Synchronous Step-Down Regulator 2006/12/20Rev. 1.6 Champion Microelectronic Corporation Page 9 APPLICATION CIRCUIT Application Circuit for USB device VIN SW CM3706 RUN GND V FB 2.5V TO 5.5V Cin 4.7uF Cout 10uF 22PF 634k 2.2uH 316K OUT IN Zener 5.6V Figure 3 Application Circuit for USB device

1.5MHz, 600mA Synchronous Step-Down Regulator 2006/12/20Rev. 1.6 Champion Microelectronic Corporation Page 10 PACKAGE DIMENSION Package Description Note5: Package outline exclusive of mold flash and metal burr.

1.5MHz, 600mA Synchronous Step-Down Regulator 2006/12/20Rev. 1.6 Champion Microelectronic Corporation Page 11 IMPORTNT 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 TEL : +886-3-567 9979 T E L : +886-2-2788 0558 FAX: +886-3-567 9909 F A X : +886-2-2788 2985 http://www.champion-micro.com