TIGER ELECTRONIC CO.,LTD 1.5A 280kHz Boost Regulators DESCRIPTIONS： AMC3202DMF Outline Drawing: 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 AMC3202DMF 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. FEATURES Integrated Power Switch: 1.5A Guaranteed. Wide Input Range: 2.7V to 30V. 40V Power Switch Input Voltage. High Frequency Allows for Small Components. Minimu m External Components. Built in Over Current Protection. APPLICATION TFT-LCD Power Management LCD Monitor/TV LED Backlight Driver 1/6 AMC3202DMF BLOCK DIAGRAM AND PI N CONFIGURATION PIN DESCRIPTION Pin No. Pin Name 1 COMP 2 FB 3 NC 4 EN 5 Vcc 6 AGND 7 PGND 8 Vsw Pin Function L o o p c o mp e n s a tio n p in . T h is p in is th e o u tp u t o f th e e r r o r a mp lif ie r a n d is u s e d f o r lo o p c o mp e n s a tio n . L o o p c o mp e n s a tio n c a n b e imp le me n te d b y a s imp le RC n e tw o r k . Feedback pin. Sense th e ou tput voltage and referenced to 1.276V. When the voltage at this pin falls below 0.4V,chip switching-frequency reduces to a mu ch lower frequency. No connection.Keep floating. 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. Input power supply pin. Supply power to the IC and should have a bypass capacitor connected to AGND Analog ground. Provide a clean ground for the co ntroller circuitry and should not be in th e path of large cu rrents.This pin is connected to the IC substrate. Power ground. This pin is the ground connection for the emitter of the power switching transistor.Connectio n to a good ground plane is essential. 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. 2/6 AMC3202DMF ABSOLUTE MAXIMUM RATINGS (Ta=25 °C) Characteristic Symbol Value Unit Input Voltage Vcc 30 V Switch Input Voltage, Vsw 40 V Tj 150 °C Tstg -65 ～ +150 °C 260 °C Maximum Operating Junction Temp erature Storage Temperature Lead Temp erature(Soldering,10seconds) * 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. ELECTRICAL CHARACTERISTICS (Unless otherwise noted: 2.7V<Vcc<30V,Ta=25℃ ) Characteristics FB Reference Voltage Test conditions VCOMP tied to FB;Measure at FB FB Input Current F B R e f e r e n c e Vo l t a g e L i n e Regulation E r r o r A m p Tr a n s c o n d u c t a n c e FB=VREF V C O M P = F B , 2.7V<Vcc<30V Error Amp Gain * IVCOMP=±25µA VCOMP Source Current F B = 1 . 0 V, V C O M P = 1 . 2 5 V VCOMP Sink Current F B = 1 . 5 V, V C O M P = 1 . 2 5 V V C O M P H i g h C l a m p Vo l t a g e F B = 1 . 0 V, V C O M P s o u r c e s 2 5 µ A V C O M P L o w C l a m p Vo l t a g e Base Operating Frequency F B = 1 . 5 V, V C O M P s i n k s 2 5 µ A Reduce VCOMP from 1.5V until switching stops FB=1V Reduced Operating Frequency FB=0V VCOMP Threshold Maximim Duty Cycle FB Frequency Shift Threshold Synchronization range Synchronization Tr a n s i t i o n T h r e s h o l d EN Bias Current Frequency drops to operating frequency Typ Max Unit V 1.276 1.300 µA 0.1 1.0 0.01 0.03 %/V 300 200 25 200 1.5 0.25 550 500 50 625 1.7 0.50 800 uMho 90 1500 1.9 0.65 µA 0.75 1.05 1.30 V 230 30 90 280 52 94 310 120 kHZ 0.36 0.40 0.44 V 500 kHZ 320 Pulse Rise time=20ns 2.5 EN=0V EN=3.0V -15 Shutdown Threshold Shutdown Delay reduced Min 1.246 -1.0 2.7V≤Vcc≤12V 1 2 V≤Vcc≤3 0 V 0.50 12 12 V/V µA V V kHZ % V -3.0 3.0 0.85 80 36 8.0 1.20 350 200 µA V µS 3/6 AMC3202DMF ISWITCH=1.5A ISWITCH=1.0A ISWITCH=10mA S w i t c h S a t u r a t i o n Vo l t a g e Switch Current Limit 50% duty cycle 80% duty cycle M i n i m u m P u l s e Wi d t h F B = 0 V, I s w = 1 . 0 A Switch Leakage V s w = 4 0 V, V c c = 0 V ∆Icc/∆Ivsw 2 . 7 V ≤ V c c ≤ 1 2 V, 1 0 m A ≤ I s w ≤ 1 . 0 A 1 2 V ≤ V c c ≤ 3 0 V, 1 0 m A ≤ I s w ≤ 1 . 0 A 2 . 7 V ≤ V c c ≤ 1 2 V, 1 0 m A ≤ I s w ≤ 1 . 5 A 1 2 V ≤ V c c ≤ 3 0 V, 1 0 m A ≤ I s w ≤ 1 . 5 A Operating Current Isw=0 V C O M P < 0 . 8 V, E N = 0 V, 2.7V≤Vcc≤12V V C O M P < 0 . 8 V, E N = 0 V, 12V≤Vcc≤30V Shutdown Mode Current Minimum Operation Vo l t a g e Thermal shutdown Input Vsw switching,maximum Isw=10mA 150 Thermal Hysteresis * 1.5 1.4 100 0.8 0.75 0.09 0.45 1.8 1.6 250 2.0 10 17 5.5 2.3 2.1 300 100 30 100 30 100 8.0 12 60 100 µA 2.45 2.70 V 180 25 210 ℃ 1.5 V A nS µA mA/A mA ℃ Guaranteed by design,not 100% tested in production. APPLICATION CIRCUIT AMC3202DMF 4/6 AMC3202DMF APPLICATION SUMMARY 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 mu ltiple 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: AMC3202DMF 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 maximu m output voltage is determined by the VSW pin maximu m voltage minus the output diode forward voltage. Referring to typical application circuit, the output voltage is set by the below formula(1): where, V F is the output diode D F forward voltage. When choosing the inductor, one mu st consider factors such as peak current, core and ferrite material, output voltage ripple, EMI, temp erature range, physical size, and cost. 5/6 AMC3202DMF 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: 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 0.3¦ ﹐ work well up to full 1.5A switch current. The V I N ripple is determined by the product of the inductor current ripple and the ESR of input capacitor, and the V O U T 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. The goal of frequency comp ensation is to achieve desirable transient response and DC regulation while ensuring the stability of the system. A typical comp ensation network, as shown in the typical application circuit, provides a frequency response of two poles and one zero. The loop frequency comp ensation 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. 6/6