AMS1073 AMS | Alldatasheet

Document overview

  • Manufacturer or author: pROVIDED bY alldatasheet.com(free datasheet download site)
  • PDF pages: 6

Technical content

DESCRIPTION

The AMS1073 is a monolithic step-down switch mode converter with a built-in power MOSFET. It achieves 1.2A peak output current over a wide input supply range with excellent load and line regulation. Current mode operation provides fast transient response and eases loop stabilization. Fault condition protection includes cycle-by-cycle current limiting and thermal shutdown. The AMS1073 requires a minimum number of readily available standard extern al components. The AMS1073 is available in SOT23-6 packages.

FEATURES

  • 1.2A Peak Output Current
  • 0.35 Ω Internal Power MOSFET Switch
  • Stable with Low ESR Output Ceramic Capacitors
  • Up to 92% Efficiency
  • 0.1 μA Shutdown Mode
  • Fixed 1.4MHz Frequency
  • Thermal Shutdown
  • Cycle-by-Cycle Over Current Protection
  • Wide 4.5V to 24V Operating Input Range
  • Output Adjustable from 0.81V to 15V
  • Available in SOT23-6 Packages

APPLICATIONS

  • Distributed Power Systems
  • Battery Charger
  • Pre-Regulator for Linear Regulators
  • WLED Drivers TYPICAL APPLICATION AMS1073 SW FB BST GND IN EN VOUT 3.3V @ 1.2AD1 B230A VIN 12V OFF ON 10uF 10nF L1 4.7uH 49.9K 16.2K 22uF

ORDERING INFORMATION

Part Number Package Top Marking Free Air Temperature (T A) AMS1073 SOT23-6 -40°C to +85°C PACKAGE REFERENCE BST GND FB SW IN EN TOP VIEW ABSOLUTE MAXIMUM RATINGS (1) Continuous Power Dissipation (TA = +25°C) (2) Recommended Operating Conditions (3) Thermal Resistance (4) θJA θJC Notes: 1) Exceeding these ratings may damage the device. 2) The maximum allowable power dissipation is a function of the maximum junction temperature T J(MAX), the junction-to- ambient thermal resistance θJA, and the ambient temperature TA. The maximum allowable continuous power dissipation at any ambient temperature is calculated by PD(MAX)=(TJ(MAX)- TA)/θJA. Exceeding the maximum allowable power dissipation will cause excessive die temperature, and the regulator will go into thermal shutdown. Internal thermal shutdown circuitry protects the device from permanent damage. 3) The device function is not guaranteed outside of the recommended operating conditions. 4) Measured on JESD51-7, 4-layer PCB..

ELECTRICAL CHARACTERISTICS

VIN = 12V, TA = +25°C, unless otherwise noted. Parameters Symbol Condition Min Typ Max Units Feedback Voltage V FB 4.5V ≤ VIN ≤ 24V 0.790 0.810 0.830 V Feedback Current I FB V FB = 0.8V 0.1 μA Switch-On Resistance (5) R DS(ON) 0.35 Ω Switch Leakage V EN = 0V, VSW = 0V 10 μA Current Limit (5) 1.8 A Oscillator Frequency f SW VFB = 0.6V 1.2 1.4 1.7 MHz Fold-back Frequency V FB = 0V 460 kHz Maximum Duty Cycle V FB = 0.6V 87 % Minimum On-Time (5) t ON 100 ns Under Voltage Lockout Threshold Rising 2.5 2.8 3.1 V Under Voltage Lockout Threshold Hysteresis 150 mV EN Input Low Voltage 0.4 V EN Input High Voltage 1.2 V VEN = 2V 2.1 EN Input Current VEN = 0V 0.1 μA Supply Current (Shutdown) I S V EN = 0V 0.1 1.0 μA Supply Current (Quiescent) I Q VEN = 2V, VFB = 1V 0.8 1.0 mA Thermal Shutdown (5) 150 °C Note: 5) Guaranteed by design. PIN FUNCTIONS Pin # Name Description

1 BST

Bootstrap. A capacitor is connected between SW and BS pins to form a floating supply across the power switch driver. This capacitor is nee ded to drive the power switch’s gate above the supply voltage.

2 GND

Ground. This pin is the voltage reference for the regulated output voltage. For this reason care must be taken in its layout. This node should be placed outside of the D1 to C1 ground path to prevent switching current spikes from inducing voltage noise into the part. 3 FB Feedback. An external resistor divider from t he output to GND, tapped to the FB pin sets the output voltage. To prevent current limit run aw ay during a short circuit fault condition, the frequency foldback comparator lowers the osc illator frequency when the FB voltage is below 250mV. 4 EN On/Off Control Input. Pull EN above 1.2V to turn the device on. For automatic enable, connect a 100kΩ resistor between this pin and Vin pin. 5 IN Supply Voltage.The AMS1073 operates from a +4.5V to +24V unregulated input.C1 is needed to prevent large voltage spikes from appearing at the input. 6 SW Switch Output.

1.4MHz/460KHz RAMP GENERATOR DRIVER CURRENT SENSE AMPLIFIER ERROR AMPLIFIER CURRENT LIMIT COMPARATOR PWM COMPARATOR D x20 REGULATOR REFERENCE EA-- + -- S R R Q 27pF 1pF Functional Block Diagram

TYPICAL APPLICATION CIRCUITS VIN Notes: 1) D3 can be installed if VIN < 5V 2) D2 can be installed if VOUT < 5V 3) No need for both D2 and D3 VOUT 3.3V 10nF 1N4148 (Optional) AMS1073 FB SW BS GND EN IN 15 4 6 OFF ON 1.4MHz, 3.3V Output at 1A Step-Down Converter VOUT (V) R1 (k Ω) R2 (k Ω) Resistor Selection for Common Output Voltages Vout=0.81X(1+R1/R2) 10uF 22uF 4.7uH 49.9KR2 16.2K 1N4148 (Optional)

A - - 1.35 A1 0.04 - 0.15 A2 1.00 1.10 1.20 A3 0.55 0.65 0.75 D 2.72 2.92 3.12 E 2.60 2.80 3.0 E1 1.40 1.60 1.80 e 0.95BSC e1 1.90BSC L 0.30 - 0.60 θ 0 - 8°