Datasheet ADP2370, ADP2371 (Analog Devices)

High Voltage, 1.2 MHz/600 kHz, 800 mA, Low Quiescent Current Buck Regulator Data Sheet ADP2370/ ADP2371 FEATURES TYPICAL APPLICATION CIRCUIT Input voltage range: 3.2 V to 15 V, output current: 800 mA VIN = 6V Quiescent current < 14 μA in power saving mode (PSM) CIN 10µF >90% efficiency POWER GOOD Force PWM pin (SYNC), 600 kHz/1.2 MHz frequency pin ADP2370/ (FSEL) ADP2371 VIN PGND 1 8 Fixed outputs: 0.8 V, 1.2 V, 1.5 V, 1.8 V, 2.5 V, 3.0 V, 3.3 V, 5 V, and adjustable option 1.2MHz VOUT = 3.3V FSEL SW 100% duty cycle capability 2 7 600kHz COUT Initial accuracy: ±1% ON 10µF EN PG Low shutdown current: <1.2 μA OFF 3 6 AGND Quick output discharge (QOD) option (EXPOSED PAD) SYNC FB Synchronizable to an external clock 4 5 8-lead, 0.75 mm × 3 mm × 3 mm LFCSP (QFN) package
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Supported by ADIsimPower design tool
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APPLICATIONS
Figure 1.
Portable and battery-powered equipment Automatic meter readers (WSN) Point of sales and transaction processing instruments Medical instruments Medium format display tablets and pads GENERAL DESCRIPTION
The ADP2370/ADP2371 are high efficiency, low quiescent current, A power-good output is available to indicate when the output 800 mA buck (step-down) dc-to-dc converters in small 8-lead, voltage is below 92% of its nominal value. 3 mm × 3 mm LFCSP (QFN) packages. The total solution requires The ADP2371 is identical to the ADP2370 except that the only three tiny external components. ADP2371 includes the addition of an integrated switched The buck regulator uses a proprietary high speed current mode, resistor, quick output discharge function (QOD) that auto- constant frequency PWM control scheme for excellent stability matically discharges the output when the device is disabled. and transient response. The need for an external rectifier is elimi- Both devices include an internal power switch and a synchronous nated by using a high efficiency synchronous rectifier architecture. rectifier for minimal external part count and high efficiency. To ensure the longest battery life in portable applications, the The ADP2370/ADP2371 also include internal soft start and ADP2370/ADP2371 employ a power saving variable frequency internal compensation for ease of use. mode that reduces the switching frequency under light load During a logic controlled shutdown, the input is disconnected conditions. The ADP2370/ADP2371 operate from input voltages from the output and the regulator draws less than 1.2 μA from of 3.2 V to 15 V allowing the use of multiple alkaline/NiMH, the input source. Other key features include undervoltage lockout lithium cells, or other standard power sources. to prevent deep battery discharge and soft start to prevent input The ADP2370/ADP2371 offer multiple options for setting the overcurrent at startup. Short-circuit protection and thermal over- operational frequency. The ADP2370/ADP2371 can be synchro- load protection circuits prevent damage under adverse conditions. nized to a 600 kHz to 1.2 MHz external clock or it can be forced The ADP2370/ADP2371 each use one 0805 capacitor, one 1206 to operate at 600 kHz or 1.2 MHz via the FSEL pin. The ADP2370/ capacitor, and one 4 mm × 4 mm inductor. The total solution ADP2371 can be forced to operate in PWM mode (FPWM) when size is about 53 mm2 resulting in a very small footprint solution noise considerations are more important than efficiency. to meet a variety of portable applications.
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Document Outline Features Applications Typical Application Circuit General Description Table of Contents Revision History Specifications Recommended Specifications: Capacitors Absolute Maximum Ratings Thermal Data Thermal Resistance ESD Caution Pin Configuration and Function Descriptions Typical Performance Characteristics Buck Output Theory of Operation PWM Operation PSM Operation Features Descriptions Precision Enable Forced PWM or PWM/PSM Selection Quick Output Discharge (QOD) Function Short-Circuit Protection Undervoltage Lockout Thermal Protection Soft Start Current Limit 100% Duty Cycle Synchronizing Power Good Applications Information ADIsimPower Design Tool External Component Selection Selecting the Inductor Output Capacitor Input Capacitor Adjustable Output Voltage Programming Efficiency Power Switch Conduction Losses Inductor Losses Switching Losses Transition Losses Recommended Buck External Components Capacitor Selection Output Capacitor Input Bypass Capacitor Input and Output Capacitor Properties Thermal Considerations PCB Layout Considerations Packaging and Ordering Information Outline Dimensions Ordering Guide