GS1661 1MHz, 2A Step-Up Current Mode PWM Converter General Description The GS1661 is a current mode boost DC-DC converter. Its PWM circuitry with built-in 0.25Ω power MOSFET make this regulator highly power efficient. The internal compensation network also minimizes as much as 6 external component counts. The non-inverting input of error amplifier connects to a 0.6V precision reference voltage and internal soft-start function can reduce the inrush current. The GS1661 is available in the SOT23-6L package and provides space-saving PCB for the application fields. Features Adjustable Output up to 24V Internal Fixed PWM frequency: 1.0MHz Precision Feedback Reference Voltage: 0.6V (±2%) Internal 0.25Ω, 2A, 26V Power MOSFET Shutdown Current: 0.1μA Over Voltage Protection Over Temperature Protection Adjustable Over Current Protection: 0.5A ~ 2.5A Package: SOT23-6L Applications Chargers LCD Displays Digital Cameras Handheld Devices Portable Products web:http://www.zgsemi.com TEL:0755-27668758/29126058 1/8 www.086ic.cn GS1661 Function Block Diagram Pin Descriptions Name SOT23-6L Top View LX 1 6 OC GND 2 5 VCC FB 3 4 EN No. I / O Description LX 1 O Power Switch Output GND 2 P IC Ground FB 3 I Error Amplifier Inverting Input EN 4 I Enable Control (Active High) VCC 5 P IC Power Supply OC 6 I Adjustable Current Limit (Floating Available) web:http://www.zgsemi.com TEL:0755-27668758/29126058 2/8 www.086ic.cn GS1661 Ordering Information Part Number Code GS1661HR-GS Operating Temperature Package MOQ Description -40°C ~ 85°C SOT23-6L 3000EA Tape & Reel AL Absolute Maximum Ratings Parameter Symbol Conditions Min. Typ. Max. Unit Supply Voltage VCC 0 6 V OVP Voltage VOVP 0 28 V VLX 0 28 V 0 6 V LX Voltage EN,FB Voltage Power Dissipation PD SOT23-6L @TA=25°C 455 mW Thermal Resistance (Note1) θJA SOT23-6L +220 °C / W Junction Temperature TJ +150 °C Operating Temperature TOP -40 +85 °C Storage Temperature TST -65 +150 °C +260 °C Lead Temperature (soldering, 10 sec) Note1: θJA is measured in the natural convection at TA=25°C on a low effective thermal conductivity test board of JEDEC 51-3 thermal measurement standard. IR Re-flow Soldering Curve web:http://www.zgsemi.com TEL:0755-27668758/29126058 3/8 www.086ic.cn GS1661 Recommended Operating Conditions Parameter Symbol Supply Voltage VIN Operating Temperature Range TA Conditions Ambient Temperature Min. Max. Unit 2.6 Typ. 5.5 V -40 +85 °C DC Electrical Characteristics (VCC=3.3V, TA=25°C,unless otherwise specified) Parameter Symbol Conditions Min. Typ. Max. Unit 5.5 V System Supply Input Input Supply Range Under Voltage Lockout VCC 2.6 VUVLO UVLO Hysteresis 2.2 V 0.1 V Quiescent Current ICC VFB=0.66V, No switching 0.16 mA Average Supply Current ICC VFB=0.55V, Switching 2.84 mA Shutdown Supply Current ICC VEN=GND 0.1 µA FOSC VFB=1.0V Oscillator Operation Frequency Frequency Change with Voltage Maximum Duty Cycle 0.8 △f / △V VCC=2.7V to 5.5V TDUTY 1.0 1.2 MHZ 5 % 90 % Reference Voltage Feedback Voltage 0.588 VREF Line Regulation 0.6 0.612 0.05 VCC=2.7V～5.5V V %/V Enable Control Enable Voltage VEN Shutdown Voltage VEN 0.96 V 0.6 V MOSFET On Resistance of Driver RDS (ON) ILX=2A Ω 0.25 Protection OVP Threshold Voltage VOVP 27 V OVP Sink Current ISINK 5 µA OCP Current IOCP Adjustable OCP Current IOCP OTP Temperature TOTP With External Resistor： 10k~100k 2 2.6 A 0.5 2.6 A +150 web:http://www.zgsemi.com TEL:0755-27668758/29126058 4/8 °C www.086ic.cn GS1661 Function Description Operation The GS1661 is a current mode boost converter. The constant switching frequency is 1MHz and operates with pulse width modulation (PWM). Build-in 26V / 2A MOSFET provides a high output voltage. The control loop architecture is peak current mode control; therefore slope compensation circuit is added to the current signal to allow stable operation for duty cycles larger than 50%. Soft Start Function Soft start circuitry is integrated into GS1661 to avoid inrush current during power on. After the IC is enabled, the output of error amplifier is clamped by the internal soft-start function, which causes PWM pulse width increasing slowly and thus reducing input surge current. Current Limit Program A resistor between OC and GND pin programs peak switch current. The resistor value should be between 10k and 100k. The current limit will be set from 2.5A to 0.5A. Keep traces at this pin as short as possible. Do not put capacitance at this pin. To set the over current trip point according to the following equation: IOCP 48000 R3 Over Voltage Protection (OVP) In some condition, the resistive divider may be unconnected, which will cause PWM signal to operate with maximum duty cycle and power switch voltage is boosted higher and higher. The power MOSFET will be turned off immediately, when the power switch voltage exceeds the OVP threshold level. The FP6291’s OVP threshold is 27V. Over Temperature Protection (OTP) GS1661 will turn off the power MOSFET automatically when the internal junction temperature is over 150°C. The power MOSFET wake up when the junction temperature drops 30°C under the OTP threshold temperature. Output Disconnect When power on and the EN pin will be pulled high. The GS1661 start up and operates. The external PMOS is turned on and current through it for output loading. While output loading is increase, output voltage is drop. When the FB pin voltage is under 0.3V, the EN pin sinks 20µA current, the external PMOS will be turn off. The output short condition will be disconnected. web:http://www.zgsemi.com TEL:0755-27668758/29126058 5/8 www.086ic.cn GS1661 Application Information Inductor Selection Inductance value is decided based on different condition. 4.7 to 22µH inductor value is recommended for general application circuit. There are three important inductor specifications, DC resistance, saturation current and core loss. Low DC resistance has better power efficiency. Also, it avoid inductor saturation which will cause circuit system unstable and lower core loss at 1 MHz. Capacitor Selection The output capacitor is required to maintain the DC voltage. Low ESR capacitors are preferred to reduce the output voltage ripple. Ceramic capacitor of X5R and X7R are recommended, which have low equivalent series resistance (ESR) and wider operation temperature range. Diode Selection Schottky diodes with fast recovery times and low forward voltages are recommended. Ensure the diode average and peak current rating exceed the average output current and peak inductor current. In addition, the diode’s reverse breakdown voltage must exceed the output voltage. Output Voltage Programming The output voltage is set by a resistive voltage divider from the output voltage to FB. The output voltage is: R1 VOUT 0.6 V 1 R2 Layout Considerations 1. The power traces, consisting of the GND trace, the LX trace and the VCC trace should be kept short, direct and wide. 2. LX、L and D switching node, wide and short trace to reduce EMI. 3. Place CIN near VCC pin as closely as possible to maintain input voltage steady and filter out the pulsing input current. 4. The resistive divider R1and R2 must be connected to FB pin directly as closely as possible. 5. FB is a sensitive node. Please keep it away from switching node, LX. 6. The GND of the IC, CIN and COUT should be connected close together directly to a ground plane. web:http://www.zgsemi.com TEL:0755-27668758/29126058 6/8 www.086ic.cn GS1661 Typical Application Vin 3.3~4.2V L1 3.3uH/6A Vout 5V D1 SS34 IC1 C2 22uF/6.3V/x5R 6 OC LX 1 5 Vcc GND 2 4 EN FB 3 R3 110k C6 C7 0.1uF 47uF/16V/x5R C1 0.1uF R2 18k GS1661 R4 15k General Boost Converter GS1661 SCP Detect and Load Disconnect web:http://www.zgsemi.com TEL:0755-27668758/29126058 7/8 www.086ic.cn GS1661 Package Outline SOT23-6L Unit: mm Symbols Min. (mm) Max. (mm) A 1.050 1.450 A1 0.050 0.150 A2 0.900 1.300 b 0.300 0.500 c 0.080 0.220 D 2.900 BSC E 2.800 BSC E1 1.600 BSC e 0.950 BSC e1 1.900 BSC L 0.300 0.600 L1 0.600 REF L2 0.250 BSC θ° 0° 8° θ1° 3° 7° θ2° 6° 15° Note: 1. Package dimensions are in compliance with JEDEC outline: MO-178 AB. 2. Dimension “D” does not include molding flash, protrusions or gate burrs. 3. Dimension “E1” does not include inter-lead flash or protrusions. web:http://www.zgsemi.com TEL:0755-27668758/29126058 8/8 www.086ic.cn