HT8097ARTZ

HT8097A 1.5MHz, 2A Synchronous Step-Down Converter FEATURES GENERAL DESCRIPTION • • • • • • • • • • • • The HT8097A is a 1.5MHz constant frequency, current mode step-down converter. It is ideal for portable equipment requiring very high current up to 2A from single-cell Lithium-ion batteries while still achieving over 90% efficiency during peak load conditions. The HT8097A also can run at 100% duty cycle for low dropout operation, extending battery life in portable systems while light load operation provides very low output ripple for noise sensitive applications. HT8097A can supply up to 2A output load current from a 2.3V to 6V input voltage and the output voltage can be regulated as low as 0.6V. The high switching frequency minimizes the size of external components while keeping switching losses low. The internal slope compensation setting allows the device to operate with smaller inductor values to optimize size and provide efficient operation. The HT8097A is offered in a low profile (1mm) 6-pin, thin SOT package, and is available in an adjustable version. This device offers two operation modes, PWM control and PFM Mode switching control, which allows a high efficiency over the wider range of the load. High Efficiency: Up to 96% 1.5MHz Constant Frequency Operation 2A Output Current No Schottky Diode Required 2.3V to 6V Input Voltage Range Output Voltage as Low as 0.6V PFM Mode for High Efficiency in Light Load 100% Duty Cycle in Dropout Operation Short Circuit Protection Thermal Fault Protection Inrush Current Limit and Soft Start SOT23-6 package APPLICATIONS • • • • • • Cellular and Smart Phones Wireless and DSL Modems PDAs Portable Instruments Digital Still and Video Cameras PC Cards TYPICAL APPLICATION Figure 1. Basic Application Circuit Rev. 01 HT8097A ABSOLUTE MAXIMUM RATINGS (Note 1) Input Supply Voltage ……………………………………………………………………………………… -0.3V to 6.5V Operating Temperature Range …………………………………………………………………………-40°C to +85°C EN,FB Voltages….……………………………………………………………………………………-0.3 to (Vin+0.3V) Lead Temperature(Soldering,10s) …..…………………………………………………………………………+300°C LX Voltage …………………………………………………………………………………………-0.3V to (Vin+0.3V) Storage Temperature Range ……………………………………………………………………………-65°C to 150°C PIN CONFIGURATION PIN DESCRIPTION NAME PIN FUNCTION EN 1 Chip Enable Pin. Drive EN above 1.5V to turn on the part. Drive EN below 0.3V to turn it off. Do not leave EN floating. GND 2 Analog ground pin. LX 3 Power Switch Output. It is the switch node connection to Inductor. This pin connects to the drains of the internal P-ch and N-ch MOSFET switches. VIN 4 Analog supply input pin. NC 5 No Connect. FB 6 Output Voltage Feedback Pin. An internal resistive divider divides the output voltage down for comparison to the internal reference voltage. Rev. 01 HT8097A ELECTRICAL CHARACTERISTICS (Note 3) (VIN=VEN=3.6V, VOUT=1.8V, TA = 25°C, unless otherwise noted.) Parameter Conditions MIN Input Voltage Range 2.3 UVLO Threshold 1.7 Input DC Supply Current PWM Mode PFM Mode Shutdown Mode Regulated Feedback Voltage VFB (Note 4) Vout = 90%, Iload=0mA Vout = 105%, Iload=0mA VEN = 0V, VIN=4.2V TYP MAX unit 6 V 1.9 2.1 V 150 40 0.1 300 75 1.0 μA μA μA μA TA = 25°C 0.588 0.600 0.612 V TA = 0°C ” 7A ” 85ƒ& 0.586 0.600 0.613 V TA = -40°C ” 7A ” 85ƒ& 0.585 0.600 0.615 V Reference Voltage Line Regulation Vin=2.5V to 5.5V Output Voltage Accuracy VIN = 2.5V to 5.5V, Iout=10mA to 2000mA Output Voltage Load Regulation Iout=10mA to 2000mA 0.2 %/A Vout=100% Vout=0V 1.5 MHz 300 kHz Oscillation Frequency 0.1 -3 %/V +3 %Vout On Resistance of PMOS ILX=100mA 100 150 mŸ On Resistance of NMOS ILX=-100mA 90 150 mŸ Peak Current Limit 4 VIN= 3V, Vout=90% EN Threshold 0.30 EN Leakage Current LX Leakage Current VEN=0V,VIN=VLX=5V A 1.0 1.50 V ±0.01 ±1.0 μA ±0.01 ±1.0 μA 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: TJ = TA + (PD) x (250°C/W). Note3: 100% production test at +25°C. Specifications over the temperature range are guaranteed by design and characterization. Note 4: Dynamic supply current is higher due to the gate charge being delivered at the switching frequency. Rev. 01 HT8097A FUNCTIONAL BLOCK DIAGRAM FUNCTIONAL DESCRIPTION The HT8097A is a high output current monolithic switch mode step-down DC-DC converter. The device operates at a fixed 1.5MHz switching frequency, and uses a slope compensated current mode architecture. This stepdown DC-DC converter can supply up to 2A output current at VIN = 3.6V and has an input voltage range from 2.3V to 6V.input capacitor is required at the output. The adjustable output voltage can be programmed with external feedback to any voltage, ranging from 0.6V to near the input voltage. It uses internal MOSFETs to achieve high efficiency and can generate very low output voltages by using an internal reference of 0.6V. At dropout operation, the converter duty cycle increases to100% and the output voltage tracks the input voltage minus the low RDS(ON) drop of the P-channel high-side MOSFET and the inductor DCR. The internal error amplifier and compensation provides excellent transient response, load and line regulation. Internal soft start eliminates any output voltage overshoot when the enable or the input voltage is applied. Rev. 01 HT8097A Setting the Output Voltage Figure 1 shows the basic application circuit for the HT8097A. The HT8097A can be externally programmed. Resistors R1 and R2 in Figure 1 program the output to regulate at a voltage higher than 0.6V. The external resistor sets the output voltage according to the following equation: VOUT 0.6 u (1 + R1 R2 ) R1 (VOUT / 0.6 1) u R2 APPLICATIONS INFORMATION Inductor Selection For most designs, the HT34720 operates with inductors of 1μHto 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: L VOUT u VIN VOUT ) V IN u 'I L u f OSC Where 'I L is inductor Ripple Current. Large value inductors result in lower ripple current and small value inductors result in high ripple current. For optimum voltage-positioning load transients, choose an inductor with DC series resistance in the 50mŸ WR 150PŸ UDQJH. 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 should 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 22μF ceramic capacitor for most applications is sufficient. A large value may be used for improved input voltage filtering. Rev. 01 HT8097A PACKAGE INFORMATION SOT23-6 Note: 1) All dimensions are in millimeters. 2) Package length does not include mold flash,protrusion or gate burr. 3) Package width does not include interlead flash or protrusion. 4) Lead coplanarity (bottom of leads after forming) shall be 0.10 millimeters max. 5) Pin 1 is lower left pin when reading top mark from left to right, Rev. 01