Features and Benefits
- Selects Highest Priority Valid Supply from Two Inputs
- Wide 1.8V to 18V Operating Range
- Internal Dual 2Ω, 0.5A Switches
- Low 3.6µA Operating Current
- Low 320nA V2 Current When V1 Connected to OUT
- Blocks Reverse and Cross Conduction Currents
- Reverse Supply Protection to –15V
- Built-In V2 Test with Optional V2 Disconnect
- V2 Freshness Seal/Ship Mode
- ±1.5% Accurate Adjustable Switchover Threshold
- ±2.3% Accurate V2 Monitor and Comparator
- Overcurrent and Thermal Protection
- Thermally Enhanced 12-Pin 3mm × 3mm DFN and 12-Lead Exposed Pad MSOP Packages
The LTC4420 is a dual input monolithic PowerPath™ prioritizer, with low operating current, that provides backup switchover for keeping critical circuitry alive during brownout and power loss conditions. Unlike diode-OR products, little current is drawn from the inactive supply even if its voltage is greater than the active supply.
Internal 2Ω, current limited PMOS switches provide power path selection from a primary input (V1) or a backup input (V2) to the output. Two adjustable voltage monitors set via external resistive dividers provide flexibility in setting V1 to V2 switchover and V2 undervoltage thresholds. V1 is monitored continuously while V2 supply monitoring includes controllable low duty cycle UV monitoring. When primary input V1 drops, the ADJ monitor causes OUT to be switched to V2. When V2 drops, it is disconnected from OUT if V2DIS is low. Fast non-overlap switchover circuitry prevents reverse and cross conduction while minimizing output droop.
Auxiliary voltage monitor CMP1 provides flexible voltage monitoring and output V2OK provides V2 undervoltage status. Freshness seal mode prevents V2 battery discharge during storage or shipment.
- Low Power Battery Backup
- Portable Equipment
- Point-of-Sale (POS) Equipment
Product Lifecycle Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (1)
Demonstration circuit DC2208A uses the LTC4420 to provide backup switchover, keeping the output load powered during brownout or power loss conditions. Priority is assigned by supply connection to the V1 and V2 inputs. The power source connected to the V1 input has a higher priority, and it is monitored continuously by adjustable comparator (ADJ) with the proper threshold arranged by an external resistive divider. If the input voltage V1 exceeds 1.55V (1.8V worst case) and the ADJ pin is above 1.097V for at least 64ms after V1 has powered up, and then stays above 1.047V, V1 is considered valid, and the LTC4420 connects V1 to load (OUT pin). If V1 drops below 1.52V, or the ADJ pin voltage is lower than 1.047V, V1 is considered invalid, and LTC4420 switches V2 to load, if the V2DIS pin voltage is above 0.9V. If the V2DIS pin voltage is below 0.2V, V2 to load connection is activated only if V2UV is >0.387V.
Tools & Simulations
LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.
Models for the following parts are available in LTspice:
LTC4420 Companion Parts
Recommended Related Parts
Solutions Bulletins & Brochures (1)
Press Releases (1)
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.
Sample & Buy
The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.