AMC3202 1.5A 280kHz BOOST REGULATORS www.addmtek.com DESCRIPTION FEATURES The AMC3202 is a 280kHz switching regulator with a high efficiency, 1.5A integrated switch. The part operates over a wide input voltage range, from 2.7V to 30V. The AMC3202 utilizes current mode architecture, which allows excellent load and line regulation, as well as a practical means for limiting current. Combining high frequency operation with a highly integrated regulator circuit results in an extremely compact power supply solution. Build-in thermal protection to prevent the chip over heat damage. Integrated Power Switch: 1.5A Guaranteed. Wide Input Range: 2.7V to 30V. 43V Build-in Power Switch Input Voltage. High Frequency Allows for Small Components. Minimum External Components. Built in Over Current Protection. TYPICAL APPLICATION CIRCUIT 2.7 ~ 30VDC L APPLICATIONS DF VOUT VIN CIN TFT-LCD Power Management LED Backlight COUT VCC EN Enable VSW AMC3202 DSS R2 PACKAGE PIN OUT FB SS COMP CSS CP2 AGND PGND R1 CP1 RP COMP 1 8 VSW FB 2 7 PGND SS 3 6 AGND EN 4 5 VCC SO-8 (Top View) ORDER INFORMATION SO DM 8 pin AMC3202DMF (Lead Free) Note: All surface-mount packages are available in Tape & Reel. Append the letter “T” to part number (i.e. AMC3202DMFT). The letter ”F” is marked for Lead Free process. Copyright © 2006 ADDtek Corp. 1 DD074_B -- AUGUST 2006 AMC3202 ABSOLUTE MAXIMUM RATINGS (Note) 30V 43V 150°C -65°C to 150°C 260°C Input Voltage, VCC Switch Input Voltage, VSW Maximum Operating Junction Temperature, TJ Storage Temperature Range Lead Temperature (Soldering, 10 seconds) Note: Exceeding these ratings could cause damage to the device. All voltages are with respect to Ground. Currents are positive into, negative out of the specified terminal. BLOCK DIAGRAM VCC 5 Shutdown Thermal Shutdown 2.0V Regulator 8 VSW Delay Timer EN S Oscillator Sync 4 PWM Latch Q Switch Driver R 0.4V Detector Frequency Shift 5:1 4uA SS 3 FB 2 X5 － 1.276V AGND 63mΩ ＋ ＋ － Error Amp PWM Comparator Slope Compensation ∑ 6 7 Ramp Summer PGND 1 COMP Copyright © 2006 ADDtek Corp. 2 DD074_B -- AUGUST 2006 AMC3202 PIN DESCRIPTION Pin Number Pin Name 1 COMP Loop compensation pin. This pin is the output of the error amplifier and is used for loop compensation. Loop compensation can be implemented by a simple RC network. 2 FB Feedback pin. Sense the output voltage and referenced to 1.276V. When the voltage at this pin falls below 0.4V, chip switching-frequency reduces to a much lower frequency. 3 SS Soft Start pin. Left this pin floating if soft start function is not used. 4 EN Enable pin. A TTL low will shut down the chip and high enable the chip. This pin may also be used to synchronize the part to nearly twice the base frequency. If synchronization is not used, this pin should be either tied high or left floating for normal operation. 5 VCC Input power supply pin. Supply power to the IC and should have a bypass capacitor connected to AGND. 6 AGND Analog ground. Provide a clean ground for the controller circuitry and should not be in the path of large currents. This pin is connected to the IC substrate. 7 PGND Power ground. This pin is the ground connection for the emitter of the power switching transistor. Connection to a good ground plane is essential. 8 VSW High current switch pin. Connect to the collector of the internal power switch. The open voltage across the power switch can be as high as 40V. To minimize radiation, use a trace as short as practical. Exposed Pad Heat Pad (PGND) Pin Function Heat pad. Connect to power ground. Must be soldered to electrical ground on PCB. THERMAL DATA Thermal Resistance from Junction to Ambient, θ JA 165°C /W Junction Temperature Calculation: TJ = TA + (PD × θ JA). The θJA numbers are guidelines for the thermal performance of the device/pc-board system. Connect the ground pin to ground using a large pad or ground plane for better heat dissipation. All of the above assume no ambient airflow. Maximum Power Calculation: PD(MAX)= TJ(MAX) – TA(MAX) θJA TJ (°C): Maximum recommended junction temperature TA (°C): Ambient temperature of the application θJA (° C /W): O Junction-to-Ambient thermal resistance of the package, and other heat dissipating materials. The maximum power dissipation for a single-output regulator is: PD(MAX) = [(VIN(MAX) - VOUT(NOM))] × IOUT(NOM) + VIN(MAX) × IQ Where: VOUT(NOM) = the nominal output voltage IOUT(NOM) = the nominal output current, and IQ = the quiescent current the regulator consumes at IOUT(MAX) VIN(MAX) = the maximum input voltage Then θJA = (+150 OC – TA)/PD Copyright © 2006 ADDtek Corp. 3 DD074_B -- AUGUST 2006 AMC3202 RECOMMENDED OPERATING CONDITIONS Parameter Symbol Min Supply Voltage VIN 2.7 Average Supply Current Output Voltage Typ Max Unit 30 V IIN 1.3 A VOUT 42 V TA 85°C °C Operating Free-air Temperature Range DC ELECTRICAL CHARACTERISTICS VCC = 3.3V, TA = 25°C, (Unless otherwise noted) Parameter FB Reference Voltage Conditions COMP tied to FB; Measure at FB; 2.7V≦VCC≦30V Min Typ Max Unit 1.246 1.276 1.300 V -1.0 0.1 1.0 uA - 0.01 0.03 %/V FB Input Current FB=VREF FB Reference Voltage Line Regulation COMP=FB, 2.7V≦VCC≦30V Error Amp Transconductance ICOMP=±25uA (Note) 300 550 800 uMh o Error Amp Gain (Note) 200 500 - V/V COMP Source Current FB=1.0V, COMP=1.25V 25 50 90 uA COMP Sink Current FB=1.5V, COMP=1.25V 200 625 1500 uA COMP High Clamp Voltage FB=1.0V, COMP sources 25uA 1.5 1.7 1.9 V COMP Low Clamp Voltage FB=1.5V, COMP sinks 25uA 0.25 0.50 0.65 V COMP Threshold Reduce COMP from 1.5V until switching stops 0.75 1.05 1.30 V Base Operating Frequency FB=1V 230 280 310 kHz Reduced Operating Frequency FB=0V 30 52 120 kHz Maximum Duty Cycle FB=1V 90 94 - % FB Frequency Shift Threshold Frequency drops to reduced operating frequency 0.36 0.40 0.44 V 320 - 500 kHz Synchronization Range Synchronization Pulse Transition Threshold Rise time=20ns 2.5 - - V EN Bias Current EN=0V EN=3.0V -15 - -3.0 3.0 8.0 uA 0.50 0.85 1.20 V 12 12 80 36 350 200 uS Shutdown Threshold Shutdown Delay Copyright © 2006 ADDtek Corp. 2.7V≦VCC≦12V 12V≦VCC≦30V 4 DD074_B -- AUGUST 2006 AMC3202 ISWITCH=1.5A Switch Saturation Voltage ISWITCH=1.0A, 0°C≦TJ≦85°C (Note) ISWITCH=1.0A, -40°C≦TJ≦0°C (Note) ISWITCH=10mA - 0.8 0.55 0.75 0.09 1.4 0.45 V Switch Current Limit 50% duty cycle (Note) 80% duty cycle (Note) 1.6 1.5 1.9 1.7 2.4 2.2 A Minimum Pulse Width COMP=1.4V, ISW = 1.0A 100 250 300 nS Switch Leakage VSW=43V, VCC=0V - 2.0 10 uA 2.7V≦VCC≦12V, 10mA≦ISW≦1.0A 10 17 - 30 100 30 100 mA/A 12V≦VCC≦30V, 10mA≦ISW≦1.5A - ISW=0; 2.7V≦VCC≦30V - 5.5 8.0 mA COMP＜0.8V, EN=0V, 2.7V≦VCC≦12V COMP＜0.8V, EN=0V, 12V≦VCC≦30V - 12 - 60 100 uA VSW switching, maximum ISW=10mA - 2.45 2.70 V Thermal Shutdown 150 - - °C Thermal Hysteresis - 25 - °C ∆ICC/∆Isw Operating Current Shutdown Mode Current Minimum Operation Input Voltage 12V≦VCC≦30V, 10mA≦ISW≦1.0A 2.7V≦VCC≦12V, 10mA≦ISW≦1.5A Note: Guaranteed by design, not 100% tested in production. Copyright © 2006 ADDtek Corp. 5 DD074_B -- AUGUST 2006 AMC3202 CHARACTERIZATION CURVES Icc vs. VCC During Shutdowm Switch Frequency vs. FB 25 300 VCC=3.3V TA=25°C Frequency(kHz) 250 20 200 Icc(uA) 15 150 10 100 VCC=2.7V~30V 5 50 TA=25°C 0 0 0.36 0.38 0.4 0. 42 0. 44 0 10 20 IEN vs. VEN Reference Voltage vs. Temperature 1 1. 280 VCC=3.3V 0. 75 1. 276 0.5 1. 274 0. 25 I EN(uA) Voltage(V) 1. 278 1. 272 1. 270 0 VCC=3.3V TA=25°C -0. 25 1. 268 -0.5 1. 266 -0. 75 1. 264 -1 -40 0 40 Temperature(°C) 80 120 0 3 6 9 VEN(V) VCE (SAT) vs. ISW COMP Threshold vs. Temperature 1. 2 0.7 VCC=3.3V TA=25°C 0.6 VCC=3.3V TA=25°C 1. 1 0.5 1 Voltage(V) VCE (SAT) (mV) 30 VCC(V) FB(V) 0.4 0.3 0. 9 0.2 0. 8 0.1 0. 7 0 0. 6 0 500 1000 1500 -40 Isw(mA) Copyright © 2006 ADDtek Corp. 0 40 80 120 Temperature(°C) 6 DD074_B -- AUGUST 2006 AMC3202 Shutdown Delay vs. Temperature 280 120 275 Fosc(kHz) 285 140 100 Delay(ns) Switching FOSC vs. Temperature 160 VCC=2.7V 80 VCC=12V VCC=30V 60 270 265 260 40 255 20 250 245 0 -40 0 40 80 -40 120 0 40 80 120 Temperature(°C) Temperature(°C) Minimum VCC vs. Temperature Switch Leakage vs. Temperature 1.85 0.35 1. 825 0. 3 VCC=0V TA=25°C 0.25 Current(mA) VCC,MIN(V) 1. 8 1. 775 1.75 0. 2 0.15 0. 1 0.05 1. 725 0 1. 7 -40 0 40 80 -40 120 0 40 80 120 Temperature(°C) Temperature(°C) Max Duty Cycle vs. Temperature 99.5 VCC=30V 99.3 Duty Cycle(%) VCC=2.7V 99.1 98.9 VCC=3.3V VCC=12V 98.7 VCC=2.7V ~30V TA=25°C 98.5 -40 0 40 80 120 Temperature(°C) Copyright © 2006 ADDtek Corp. 7 DD074_B -- AUGUST 2006 AMC3202 APPLICATION INFORMATION Operation: The AMC3202 incorporates a current mode control scheme, in which the duty cycle of the switch is directly controlled by switch current rather than by output voltage. The output of the oscillator turns on the power switch at a frequency of 280kHz as shown in the block diagram. The power switch is turned off by the output of the PWM comparator. A TTL low voltage will shut down the chip and high voltage enable the chip through EN pin. This pin may also be used to synchronize the part to nearly twice the base oscillator frequency. In order to synchronize to a higher frequency, a positive transition turns on the power switch before the output of the oscillator goes high, thereby resetting the oscillator. The synchronization operation allows multiple power supplies to operate at the same frequency. If synchronization is not used, this pin should be either tied high or left floating for normal operation. Component Selection: 2 .7 V D C ~ 3 0 V D C L V IN DF V OUT 22uH C IN C OUT 10uF VCC EN E n a b le D SS SS COMP C SS 22uF VSW R2 FB A M C 3202 AGND PGND R1 C P1 C P2 200pF 0 .1 u F RP 5K The AMC3202 develops a 1.276V reference from the FB pin to ground. Output voltage is set by connecting the FB pin to an output resistor divider and the maximum output voltage is determined by the VSW pin maximum voltage minus the output diode forward voltage. Referring to typical application circuit, the output voltage is set by the below formula (1): R2 ⎞ ⎛ V OUT = 1 .276V ⎜ 1 + ⎟ R1 ⎠ ⎝ 2.7V≦VOUT≦43V－VF (1) where, VF is the output diode DF forward voltage. When choosing the inductor, one must consider factors such as peak current, core and ferrite material, output voltage ripple, EMI, temperature range, physical size, and cost. Lower values are chosen to reduce physical size of the inductor, and higher values reduce ripple voltage and core loss. In continuous conduction mode, the peak inductor current is equal to average current plus half of the ripple current, which should not cause inductor saturation. Based on the tolerance of the ripple current in the circuits, the following formula (2) can be referenced: I Ripple = V IN (VOUT − V IN ) fLV OUT where, f = 280kHz. (2) In Boost circuits, the inductor becomes part of the input filter. In continuous mode, the input current waveform is triangular and does not contain a large pulsed current. This reduces the requirements imposed on the input capacitor selection. Capacitors in the range of 10uF to 100uF with an ESR less than 0.3Ω work well up to full 1.5A switch current. Copyright © 2006 ADDtek Corp. 8 DD074_B -- AUGUST 2006 AMC3202 The VIN ripple is determined by the product of the inductor current ripple and the ESR of input capacitor, and the VOUT ripple comes from two major sources, namely ESR of output capacitor and the charging/discharging of the output capacitor. Ceramic capacitors have the lowest ESR, but too low ESR may cause loop stability problems. Aluminum Electrolytic capacitors exhibit the highest ESR, resulting in the poorest AC response. One option is to parallel a ceramic capacitor with an Aluminum Electrolytic capacitor. Frequency Compensation The goal of frequency compensation is to achieve desirable transient response and DC regulation while ensuring the stability of the system. A typical compensation network, as shown in the typical application circuit, provides a frequency response of two poles and one zero. The loop frequency compensation is performed on the output of the error amplifier (COMP pin) with a series RC network. The main pole is formed by the series capacitor and the output impedance of the error amplifier. The series resistor creates a zero, which improves loop stability and transient response. A second capacitor is sometimes used to reduce the switching frequency ripple on the COMP pin. f P1 = 1 2πC P1 RO f Z1 = 1 2πC P1 R P f P2 = 1 2πC P 2 R P where, RO= error amplifier output resistance; Soft Start Through the addition of an external circuit, a soft-start function can be added to the AMC3202. Soft-start circuitry prevents the COMP pin from slamming high during startup, thereby inhibiting the inductor current from rising at a high slope. Referring to the figure shown in the following, the soft-start circuitry requires a minimum number of components and allows the soft-start circuitry to be activated any time when the EN pin is used to restart the converter. V IN 5 EN V EN V CC 4 D SS 4uA Q 3 SS C SS 1 C COMP C P1 P2 RP Resistor RP and capacitors CP1 and CP2 form the compensation network. At turn on, the voltage at the COMP pin starts to come up, charging capacitor CSS through internal transistor Q, clamping the voltage at the COMP pin such that switching begins when COMP reaches the COMP threshold, typically 1.05V. Therefore, CSS slows down the startup of the circuit by limiting the voltage on the COMP pin. The soft-start time increases with the size of CSS. Diode DSS discharges CSS when the voltage on the EN pin is low. If the shutdown function is not used with this part, the cathode of DSS should be connected to VIN. Copyright © 2006 ADDtek Corp. 9 DD074_B -- AUGUST 2006 AMC3202 PACKAGE 8-Pin Plastic S.O.I.C. SYMBOLS A A1 A2 D E H L θ° MIN. 0.053 0.002 0.189 0.150 0.228 0.016 0 MAX. 0.069 0.006 0.059 0.196 0.157 0.244 0.050 8 UNIT: INCH THERMALLY ENHANCED DIMENSIONS PAD SIZE E1 D1 90X90E 0.081 REF 0.081 REF 95X13E 0.086 REF 0.117 REF UNIT: INCH NOTES: 1. JEDEC OUTLINE. N/A 2. DIMENSIONS “D” DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS AND GATE BURRS SHALL NOT EXCEED 15mm (.005in) PER SIDE. 3. DIMENSIONS “E” DOES NOT INCLUDE INTER-LEAD FLASH, OR PROTRUSIONS. INTER-LEAD FLASH AND PROTRUSIONS SHALL NOT EXCEED .25mm (.010in) PER SIDE. Copyright © 2006 ADDtek Corp. 10 DD074_B -- AUGUST 2006 AMC3202 IMPORTANT NOTICE ADDtek 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. ADDtek 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 ADDtek 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. ADDtek assumes to no liability to customer product design or application support. ADDtek warrants the performance of its products to the specifications applicable at the time of sale. ADDtek Corp. 9F, No. 20, Sec. 3, Bade Rd., Taipei, Taiwan, 105 TEL: 2-25700299 FAX: 2-25700196 Copyright © 2006 ADDtek Corp. 11 DD074_B -- AUGUST 2006