Low-Noise Step-Up Current Mode PWM Converter FP690 General Description The FP690 is a current mode boost DC-DC converter. Its PWM circuitry with built-in 0.Ω power MOSFET makes this converter highly power efficiently. Selectable high switching frequency allows faster loop response and easy filtering with a low noise output. The non-inverting input its error amplifier is connected to an internal.4v precision reference voltage. Soft-Start time can be programmed with an external capacitor, which sets the input current ramp rate. Current mode control and external compensation network make it easy and flexible to stabilize the system. The FP690 is available in the MSOP-8L package. Combined with low ESR capacitors, it reduced PCB space for step-up applications. Features Adjustable Output from V CC to V Internal Fixed PWM Frequency: 640KHz /.MHz Frequency Selection Pin Precision Feedback Reference Voltage:.4V Internal 0.Ω,.6A, 4V Power MOSFET External Programmable Soft-Start Function (SS) Shutdown Current : 0.µA Over Current Protection Package: MSOP-8L Applications LCD Display Digital Camera Handheld Device Portable Product Typical Application Circuit V IN / 3~3.6V D SM340A VOUT / 9.V 6 VCC LX 5 3 EN FB FP690 7 COMP FREQ + 4 GND SS 8 /
Function Block Diagram Vcc EN 3 4 SS 4µA SOFT START BIAS + Power ON / OFF 8 COMP FB +.4V Error Amp. + PWM Comp. CONTROL AND DRIVER LOGIC 5 LX 7 FREQ OSCILLATOR 5µA SLOPE COMPEN - SATION Current Sense Amp. + GND 6 /
Pin Descriptions MSOP-8L FP690 Name No. I / O Description COMP O Error Amplifier Compensation Output FB I Error Amplifier Inverting Input EN 3 I Enable Control GND 4 P IC Ground LX 5 O Switch Output V CC 6 P IC Power Supply FREQ 7 O Frequency Selection SS 8 I Soft-start Control Marking Information MSOP-8L FP690 Halogen Free Lot Number Internal ID Per-Half Month Year Halogen Free: Halogen free product indicator Lot Number: Wafer lot number s last two digits For Example: 3386TB 86 Internal ID: Internal Identification Code Per-Half Month: Production period indicated in half month time unit For Example: January A (Front Half Month), B (Last Half Month) February C (Front Half Month), D (Last Half Month) Year: Production year s last digit 3/
Ordering Information Part Number Operating Temperature Package MOQ Description FP690TR-LF -40 C ~ +85 C MSOP-8L 3000EA Tape & Reel Absolute Maximum Ratings Parameter Symbol Conditions Min. Typ. Max. Unit Supply Voltage V CC 6 V RMS LX Current. A LX to GND -0.3 4 V SS,COMP to GND -0.3 V CC +0.3 V EN,FREQ,FB to GND -0.3 V CC V Junction Temperature TJ +50 Storage Temperature TS -65 +50 Thermal Resistance Lead Temperature (soldering, 0 sec) θ JA 7 / W MSOP-8L θ JC 7 / W +60 Suggested IR Re-flow Soldering Curve 4/
Recommended Operating Conditions Parameter Symbol Conditions Min. Typ. Max. Unit Supply Voltage V IN.6 5.5 V Operating Temperature -40 85 C DC Electrical Characteristics (V IN =3V, T A = 5 C, V FREQ =0V, unless otherwise noted) Parameter Symbol Test Conditions Min. Typ. Max. Unit Reference Section Output Voltage V REF COMP connected to FB..40.58 V Line Regulation V REF / V REF V CC =.6V~5.5V 0.05 % / V Output Voltage Change with T A =-40 to 5 % Temperature T A = 5 to 85 % Under Voltage Lockout Section Upper Threshold Voltage (V CC ) V UPPER.38.53 V Lower Threshold Voltage (V CC ) V LOW T A =5.33.48 V Hysteresis (V CC ) V HYS 50 mv Soft-Start Section Reset Switch Resistance R SS 00 Ω Input Source Current I SS V SS =.V.5 4.0 7.0 μa Oscillator Section Frequency f FREQ=GND 540 640 740 KH Z FREQ=V CC.00..50 MHz Frequency Change with Voltage f / V V CC =.6V to 5.5V % / V Frequency Change with Temperature f / V T A =-40 to 85 0 % Maximum Duty Cycle T DUTY FREQ=GND 79 88 % FREQ=V CC 88 % Error Amplifier Section FB Input Bias Current I BIAS V FB =.4V 40 na Trans-conductance gm I=5μA 70 40 40 μa / V Voltage Gain Av 700 V / V Output Section NMOS Current Limit I LIM V FB =V,Duty Cycle=65%..6.3 A NMOS On Resistance R DS (ON) I LX =.A 0. 0.5 Ω Output Leakage Current I LXOFF V LX =V 0.0 0 μa Current-Sense Trans-Resistance R CS 0.56 V / A 5/
Parameter Symbol Test Conditions Min. Typ. Max. Unit Control Input Section Input High Voltage V IH EN,FREQ pin V CC =.6V~5.5V 0.7 V CC V Input Low Voltage V IL EN,FREQ pin V CC =.6V~5.5V 0.3 V CC V Hysteresis EN,FREQ 0. V CC V FREQ Pull-Down Current I FREQ.8 5 9 μa EN Input Current I EN na Total Device Disable Supply Current I DISABLE EN=GND 0. 0 μa Standby Supply Current I SBY V FB =.3V 0.0 0.35 ma Average Supply Current I AVG V FB =.0V.0 5.0 ma 6/
Typical Operating Characteristics (T A = 5 C, unless otherwise noted) 00 Efficiency vs. Output Current 0.35 NO-Load Supply Current vs. Input Voltage Efficiency (%) 90 80 70 60 50 40 30 0 0 V CC =3.3V V OUT =5V 640KHz.MHz NO-Load Supply Current(mA) 0.3 0.5 0. 0.5 0. 0.05 V OUT =5V 640KHz.MHz 0 0 00 000 Output Current (ma) 0.5 3 3.5 4 4.5 5 5.5 Input Voltage(V) 00 Efficiency vs. Output Current. Output Voltage vs. Output Current 90 80. Efficiency (%) 70 60 50 40 30 0 0 V CC =3.3V V OUT =V 640KHz.MHz Output Voltage (V).9.8.7.6 Fosc=640KH Z TA=-30 TA=5 TA=85 0 0 00 000 Output Current (ma).5 0 0 40 60 80 00 0 40 60 80 00 Output Current (ma) 00 Efficiency vs. Output Current.8 Maximum Output Current vs. Input Voltage Efficiency (%) 90 80 70 60 50 40 30 0 0 V CC =5V V OUT =V 640KHz.MHz Maximum Output Current (A).6.4. 0.8 0.6 0.4 0. Fosc=640KH Z Vout=5V Vout=V 0 0 00 000 Output Current (ma) 0 3 3. 3.4 3.6 3.8 4 4. 4.4 4.6 4.8 5 Input Voltage (V) 7/
CH=Inductor Current,CH3=EN,CH4=V OUT V CC =3.3V, V OUT =V I LOAD =0mA~00mA Frequency=640KHz CH=Inductor Current,CH4= V OUT V CC =3.3V, V OUT =V I LOAD =0mA Frequency=640KHz CH=Inductor Current,CH3=EN,CH4=V OUT V CC =3.3V, V OUT =V I LOAD =00mA Freq=640KHz CH=Inductor Current,CH3=LX,CH4= V OUT AC-Coupled V CC =3.3V, V OUT =V I LOAD =00mA Freq=.MHz 8/
Function Description Voltage Reference A.4V reference regulator supplies to the FP690 error amplifier s non-inverting terminal. Error Amplifier The error amplifier compares a sample of the dc-dc converter output voltage with the.4v (V REF ) reference and generates an error signal for the PWM comparator. Output voltage of dc-dc converter is setting with the resistor divider by the following equation: V OUT R.4 R V OUT T R Error Amplifier R.4V R COMP FP690 C COMP Oscillator The switching frequency of FP690 can be selected to operate at either 640KHz or.mhz. Connect the FREQ pin to GND for 640KHz operation, or V CC for.mhz operation. FREQ pin has an internal pull-down current around 5μA. It gives user the option of selecting 640KHz operation by leaving FREQ unconnected. Soft Start The soft start is functional after power on. The interval of soft start time is determined by a capacitor connected to SS pin. When EN pin is taken high, the soft start capacitor (C SS ) is charged by a constant current of 4μA (typ). During this interval, the SS voltage directly controls the peak inductor current. The maximum load current is available after the soft-start interval is completed. Once the EN pin is taken low, the soft-start capacitor is discharged to ground to prepare for next start-up. 9/
The load must wait for the soft-start interval to finish before drawing a significant amount of load current. The duration after which the load can begin to draw maximum load current is: T MAX 6.77 0 5 C SS EN The FP690 can be turn off to reduce the supply current to 0.μA when EN is low. In this mode, the internal reference, error amplifier, comparators, and biasing circuitry turn off while the N-channel MOSFET is turned off. The boost converter s output is connected to V CC by the external inductor and catch diode. Output Current Capability The output current capability of the FP690 is a function of current limit, input voltage, operation frequency, and inductor value. Because of the slope compensation used to stabilize the feedback loop, the duty cycle affects the current limit. The output current capability is governed by the following equation: I OUT(MAX) I LIM (.6 0.4 Duty) 0.5 Duty VIN/(fosc L) VIN/ VOUT Where: I LIM =current limit specified at 65% (VOUT VIN VDIODE) Duty=duty cycle= VOUT ILIM RON VDIODE V DIODE =catch diode forward voltage at ILIM η=conversion efficiency,85%nominal Current Limitation The internal power-mos switch current is monitored cycle-by-cycle and is limited to the value not exceed.6a (Typ.). When the switch current reaches the limited value, the internal power-mos is turned off immediately until the next cycle. 0/
Typical Application Figure Typical Application Circuits VOUT / -9.V C 0.µF D3 BAV99 / SOT-3L VOUT / 7V 3 C3 4.7µF 3 C 0.µF C9 0.µF 3 C8 µf C0 µf D4 BAV99 / SOT-3L D BAV99 / SOT-3L V IN / 3~3.6V L 4.7µF D SM340A VOUT / 9.V 6 VCC LX 5 R 300K 3 EN FB FP690 C 47µF C 0.µF C3 0pF R 7.5K C4 500pF 4 COMP GND 7 FREQ 8 SS C5 0.033µF R3 47K + C6 47µF C7 0.µF Figure TFT Panel Power Supply Application Circuits /
Package Outline MSOP-8L Symbols Min. (mm) Max. (mm) A.00 A 0.000 0.50 A 0.750 0.950 D 3.000 BSC E 4.900 BSC E 3.000 BSC L 0.400 0.800 L 0.950 REF θ 0 8 Unit: mm Note:. Package dimensions are in compliance with JEDEC outline: MO-87 AA.. Dimension D does not include molding flash, protrusions or gate burrs. 3. Dimension E does not include inter-lead flash or protrusions. /