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AiT Semiconductor Inc. www.ait-ic.com A7406A DC-DC CONVERTER BUCK (STEP-DOWN) 40V , 600mA ASYNCHRONOUS REV1.0 - MAR 2018 RELEASED - - 1 - DESCRIPTION FEATURES The A7406A is a high frequency (1.8MHz) step-down switching regulator with integrated internal high- side high voltage power MOSFET. It provides single 0.6A(or less) highly efficient output with current mode control for fast loop response. The wide input range(4.2V to 40V) accommodates a variety of step- down applications. Low shutdown mode quiescent current allows use in battery-powered applications. High efficiency at light load condition is achieved by scaling down the switching frequency to reduce the switching and gate driving losses. The A7406A is available in SOT-26 package.
ORDERING INFORMATION
SPQ: 3,000pcs/Reel A7406AE6R A7406AE6VR Note V: Halogen free Package R: Tape & Reel AiT provides all RoHS products 4.2 V to 40 V operating input range 230uA operating quiescent current. Low shutdown supply current 500mΩ internal power MOSFET 1.8 MHz fixed switching frequency >90% efficiency Internally compensated Stable with ceramic output capacitors Internal soft-start Thermal shutdown function Precision current limit without current sensing resistor Available in SOT-26 Package APPLICATION High voltage power conversion Industrial power systems Power meter Battery powered systems TYPICAL APPLICATION
AiT Semiconductor Inc. www.ait-ic.com A7406A DC-DC CONVERTER BUCK (STEP-DOWN) 40V , 600mA ASYNCHRONOUS REV1.0 - MAR 2018 RELEASED - - 2 - PIN DESCRIPTION Top View Pin # Symbol Function
1 BST
Bootstrap. This is the positive power supply for the internal floating high side MOSFET driver. Connect a bypass capacitor between this pin and SW pin. 2 GND Ground. It should be connected as close as possible to the output capacitor. 3 FB Feedback. This is the input to the error amplifier. An external resistive divider connected between the output and GND is compared to the internal +0.8V reference to set the regulation voltage. 4 EN Enable input. Pull this pin below the specified threshold to disable. Pull it above the specified threshold to enable. Float this pin to disable.
5 VIN
Input Supply. A decoupling capacitor to ground is required close to this pin to reduce switching spikes. 6 SW Switch node. This is the output from the high-side switch. A low VF
AiT Semiconductor Inc. www.ait-ic.com A7406A DC-DC CONVERTER BUCK (STEP-DOWN) 40V , 600mA ASYNCHRONOUS REV1.0 - MAR 2018 RELEASED - - 3 - ABSOLUTE MAXIMUM RATINGS VIN, Supply Voltage -0.3V ~ 43V VSW, Switch Voltage -0.3V ~ VIN (MAX)+0.3V BST to SW -0.3V ~ 6.0V All Other Pins -0.3V ~ 5.0V Continuous Power Dissipation(TA=+25℃) 0.57W Junction Temperature 150℃ Lead Temperature 260℃ Storage Temperature -65°C ~ 150℃ Stress beyond above listed “Absolute Maximum Ratings” may lead permanent damage to the device. These are stress ratings only and operations of the device at these or any other conditions beyond those indicated in the operational sections of the specifications are not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. RECOMMENDED OPERATING CONDITIONS Parameter Symbol Value Unit Supply Voltage VIN 4.2 ~ 40 V Output Voltage VOUT Up to 40 V Operating Junction Temp TJ -40 ~ +125 ℃ THERMAL RESISTANCE Package θJA θJC SOT-26 220℃/W 110℃/W
AiT Semiconductor Inc. www.ait-ic.com A7406A DC-DC CONVERTER BUCK (STEP-DOWN) 40V , 600mA ASYNCHRONOUS REV1.0 - MAR 2018 RELEASED - - 4 -
ELECTRICAL CHARACTERISTICS
VIN=12V, VEN=2V, TA=25ºC, unless otherwise stated. Parameter Symbol Conditions Min. Typ. Max. Unit Feedback Voltage VFB - 0.794 - V Upper Switch ON Resistance RSW Vbst-VSW=5V - 500 - mΩ Upper Switch Leakage ISWLEAK VEN=0V, VSW=0V - 0.1 1 μA Current Limit ILIM - 1 - A Transconductance Gcs COMP to SENSE - 3 - A/V Minimum Operating Voltage VIN MIN 4.2 - - V UVLO Up Threshold VIN(UVLO) 3.3 - 4.2 V UVLO Hysteresis VIN(UVLO) HYS - 0.8 - V Soft-Start Time tSS FB from 0 to 1.8V - 0.5 - ms Oscillator Frequency fOSC - 1.8 - MHz Minimum Switch ON Time tON MIN 100 - ns Shutdown Current ISD VEN<0.3V - 3 15 μA Quiescent Current IQ VFB=0.9V，No load - 200 - μA Thermal Shutdown TSD - 150 - °C Enable up threshold VENH 1.6 - 2.0 V Enable Threshold Hysteresis VENHYS - 0.6 - V
AiT Semiconductor Inc. www.ait-ic.com A7406A DC-DC CONVERTER BUCK (STEP-DOWN) 40V , 600mA ASYNCHRONOUS REV1.0 - MAR 2018 RELEASED - - 5 - TYPICAL APPLICATION CIRCUITS
AiT Semiconductor Inc. www.ait-ic.com A7406A DC-DC CONVERTER BUCK (STEP-DOWN) 40V , 600mA ASYNCHRONOUS REV1.0 - MAR 2018 RELEASED - - 6 - BLOCK DIAGRAM
AiT Semiconductor Inc. www.ait-ic.com A7406A DC-DC CONVERTER BUCK (STEP-DOWN) 40V , 600mA ASYNCHRONOUS REV1.0 - MAR 2018 RELEASED - - 7 - DETAILED INFORMATION The A7406A is a 1.8MHz, non-synchronous, step-down switching regulator with integrated internal high side MOSFET. It provides internally compensated single 0.6A high efficient output. It features wide input voltage range, internal soft-start control, and precision current limit. Low operational quiescent current feature is suit for battery powered applications. PWM Control At heavy load or moderate load condition, the A7406A operates in a fixed frequency, peak current control mode to regulate the output voltage. A PWM cycle is initiated by the internal clock. The power MOSFET is turned on and remains on until its current reaches the value set by COMP voltage. When the power switch is off, it remains off for at least 100ns before the next cycle starts. If, in one PWM period, the current in the power MOSFET does not reach COMP set current value, the power MOSFET remains on, saving a turn- off operation. At light load condition, the A7406A operates in pulse skipping mode to improve light load efficiency. Internal Regulator Most of the internal circuitry is powered on by the 2.6V internal regulator. When VIN is higher than 4.0V, the output of the regulator is in full regulation. When VIN is lower, the output degrades. Under Voltage Lockout (UVLO) VIN Under voltage lockout (UVLO) is implemented to protect the chip from operating at insufficient supply voltage. Thermal Shutdown Thermal shutdown is implemented to prevent the chip from thermally running away. When the temperature is higher than its upper threshold, the A7406A will shut down. When the temperature is lower than its lower threshold, the chip is enabled again.
AiT Semiconductor Inc. www.ait-ic.com A7406A DC-DC CONVERTER BUCK (STEP-DOWN) 40V , 600mA ASYNCHRONOUS REV1.0 - MAR 2018 RELEASED - - 8 -
APPLICATION INFORMATION
Setting the Output Voltage The output voltage is set using a resistive voltage divider from the output voltage to FB pin. VFB=VOUT*R2/(R1+R2) The feedback resistor R1 also sets the feedback loop bandwidth with the internal compensation capacitor. Choose R1 around 124kΩ for optimal transient response. Inductor The inductor is required to supply constant current to the output load. A larger value inductor will result in lower output ripple voltage. Generally, a good rule for determining the inductance to use is to allow the peak-to-peak ripple current in the inductor to be approximately 30% of the maximum load current. Also, make sure that the peak inductor current is below the maximum switch current limit. Input Capacitor The input capacitor (C1) can be electrolytic, tantalum or ceramic. When using electrolytic or tantalum capacitors, a small, high quality ceramic capacitor, i.e. 0.1μF, should be placed as close to the IC as possible. Output Capacitor The output capacitor (C2) is used to maintain the DC output voltage. Ceramic, tantalum, or low ESR electrolytic capacitors are recommended. Low ESR capacitors are preferred to keep the output voltage ripple low.
AiT Semiconductor Inc. www.ait-ic.com A7406A DC-DC CONVERTER BUCK (STEP-DOWN) 40V , 600mA ASYNCHRONOUS REV1.0 - MAR 2018 RELEASED - - 9 -
PACKAGE INFORMATION
Dimension in SOT-26 Package (Unit: mm)
AiT Semiconductor Inc. www.ait-ic.com A7406A DC-DC CONVERTER BUCK (STEP-DOWN) 40V , 600mA ASYNCHRONOUS REV1.0 - MAR 2018 RELEASED - - 10 - IMPORTANT NOTICE AiT Semiconductor Inc. (AiT) reserves the right to make changes to any its product, specifications, 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. AiT Semiconductor Inc. 's 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 ap plications. Use of AiT products in such applications is understood to be fully at the risk of the customer. As used herein may involve potential risks of death, personal injury, or server property, or environmental damage. In order to minimize risks associ ated with the customer's applications, the customer should provide adequate design and operating safeguards. AiT Semiconductor Inc . assumes to no liability to customer product design or application support. AiT warrants the performance of its products of the specifications applicable at the time of sale.