具有高效率休眠模式的 LMR16006 SIMPLE SWITCHER® 60V 降压稳压器

iczoom188

　　1 Features

　　Ultra Low 28 µA Standby Current in ECO Mode

　　Input Voltage Range 4 V to 60 V

　　1 µA Shutdown Current

　　High Duty Cycle Operation Supported

　　Output Current up to 600 mA

　　0.7 MHz and 2.1 MHz Switching Frequency

　　Internal Compensation

　　High Voltage Enable Input

　　Internal Soft Start

　　Over Current Protection

　　Over Temperature Protection

　　Small Overall Solution Size (SOT-6L Package)

　　Create a Custom Design Using the LMR16006 with the WEBENCH Power Designer

　　2 Applications

　　Industrial Distributed Power Systems

　　Automotive

　　Battery Powered Equipment

　　Portable Handheld Instruments

Portable Media Players

该产品品牌下其它产品相关信息可咨询：https://www.iczoom.com/brand/509-c-1-20.html

　　3 Description

　　The LMR16006 is a PWM DC/DC buck (step-down) regulator. With a wide input range of 4 V to 60 V, it is suitable for a wide range of application from industrial to automotive for power conditioning from an unregulated source. The regulator’s standby current is 28 µA in ECO mode, which is suitable for battery operating systems. An ultra low 1 µA shutdown current can further prolong battery life. Operating frequency is fixed at 0.7 MHz (X version) and 2.1 MHz (Y version) allowing the use of small external components while still being able to have low output ripple voltage. Soft-start and compensation circuits are implemented internally, which allows the device to be used with minimized external components. The LMR16006 is optimized for up to 600 mA load currents. It has a 0.765 V typical feedback voltage. The device has built-in protection features such as pulse by pulse current limit, thermal sensing and shutdown due to excessive power dissipation. The LMR16006 is available in a low profile SOT-6L package.

　　The LMR16006 device is a 60 V, 600 mA, step-down (buck) regulator. The buck regulator has a very low quiescent current during light load to prolong battery life.

　　LMR16006 improves performance during line and load transients by implementing a constant frequency, current mode control which requires less output capacitance and simplifies frequency compensation design. Two switching frequency options, 0.7 MHz and 2.1 MHz, are available, thus smaller inductor and capacitor can be used. The LMR16006 reduces the external component count by integrating the boot recharge diode. The bias voltage for the integrated high side MOSFET is supplied by a capacitor on the CB to SW pin. The boot capacitor voltage is monitored by an UVLO circuit and will turn the high side MOSFET off when the boot voltage falls below a preset threshold. The LMR16006 can operate at high duty cycles because of the boot UVLO and refresh the wimp FET. The output voltage can be stepped down to as low as the 0.8 V reference. Internal soft-start is featured to minimize inrush currents.

　　The LMR16006 has two fixed frequency options, and it implements peak current mode control. The output voltage is compared through external resistors on the VFB pin to an internal voltage reference by an error amplifier which drives the internal COMP node. An internal oscillator initiates the turn on of the high side power switch. The error amplifier output is compared to the high side power switch current. When the power switch current reaches the level set by the internal COMP voltage, the power switch is turned off. The internal COMP node voltage will increase and decrease as the output current increases and decreases. The device implements a current limit by clamping the COMP node voltage to a maximum level.

　　The LMR16006 has an integrated boot regulator, and requires a small ceramic capacitor between the CB and SW pins to provide the gate drive voltage for the high side MOSFET. The CB capacitor is refreshed when the high side MOSFET is off and the low side diode conducts. To improve drop out, the LMR16006 is designed to operate at 100% duty cycle as long as the CB to SW pin voltage is greater than 3 V. When the voltage from CB to SW drops below 3 V, the high side MOSFET is turned off using an UVLO circuit which allows the low side diode to conduct and refresh the charge on the CB capacitor. Since the supply current sourced from the CB capacitor is low, the high side MOSFET can remain on for more switching cycles than are required to refresh the capacitor, thus the effective duty cycle of the switching regulator is high. Attention must be taken in maximum duty cycle applications with light load. To ensure SW can be pulled to ground to refresh the CB capacitor, an internal circuit will charge the CB capacitor when the load is light or the device is working in dropout condition.

　　The output voltage is set using the feedback pin and a resistor divider connected to the output as shown on the front page schematic. The feedback pin voltage 0.765 V, so the ratio of the feedback resistors sets the output voltage according to the following equation: VOUT = 0.765 V (1+(R1/R2)). Typically R2 will be given as 1k Ω - 100 kΩ for a starting value. To solve for R1 given R2 and Vout uses R1 = R2 ((VOUT/0.765 V)-1).

　　LMR16006 SHDN pin is a high voltage tolerant input with an internal pull up circuit. The device can be enabled even if the SHDN pin is floating. The regulator can also be turned on using 1.23 V or higher logic signals. If the use of a higher voltage is desired due to system or other constraints, a 100 kΩ or larger resistor is recommended between the applied voltage and the SHDN pin to protect the device. When SHDN is pulled down to 0 V, the chip is turned off and enters the lowest shutdown current mode. In shutdown mode the supply current will be decreased to approximately 1 µA. If the shutdown function is not to be used the SHDN pin may be tied to VIN via 100kΩ resistor. The maximum voltage to the SHDN pin should not exceed 60 V. LMR16006 has an internal UVLO circuit to shutdown the output if the input voltage falls below an internally fixed UVLO threshold level. This ensures that the regulator is not latched into an unknown state during low input voltage conditions. The regulator will power up when the input voltage exceeds the voltage level. If there is a requirement for a higher UVLO voltage, the SHDN can be used to adjust the system UVLO by using external resistors.

　　The LMR16006 implements current mode control which uses the internal COMP voltage to turn off the high side MOSFET on a cycle-by-cycle basis. Each cycle the switch current and internal COMP voltage are compared, when the peak switch current intersects the COMP voltage, the high side switch is turned off. During overcurrent conditions that pull the output voltage low, the error amplifier will respond by driving the COMP node high, increasing the switch current. The error amplifier output is clamped internally, which functions as a switch current limit.