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DS2731
Cache-Memory Battery-Backup Management IC
Complete Cache-Memory Battery-Backup IC Reduces System Cost, Component Count, and Footprint Over Current Solutions
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Status
Active: In Production.
Description
The DS2731 is a complete power-management solution for modular backup applications. It is well-suited for 2.5V and below memory bus voltages, with an input voltage of 12V. The DS2731 includes an internal MOSFET switching power stage for charging a one-cell lithium chemistry battery. It has a fully integrated synchronous buck regulator capable of supplying up to 450mA of cache backup supply current, and the necessary logic and power devices for handling the switchover from system power to battery power. The battery charging method of the DS2731 is constant current/constant voltage (CCCV). Output voltage can be margined from 3.8V to 4.6V using a resistor-divider. Charge is terminated when the charging current falls below 5% of full charge current. Switchover to battery backup is initiated by an internal comparator and occurs automatically when a sensed-input voltage drops below 2.93V. At light loads, the 2MHz internal synchronous buck regulator operates in burst mode for maximum efficiency. All nonessential functions of the DS2731 are disabled while supplying holdup current to the cache memory, and the IC goes into very low-current dormant mode when the battery voltage drops below a user-settable threshold. The DS2731 keeps track of charge status and signals the user through open-drain I/O pins that can be used to drive LEDs.
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Data Sheet
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An evaluation kit is available: DS2731EVKIT
Key Features
- Lithium Chemistry CCCV Charger
- Adjustable Regulated Charging Up to 1.5A DC
- Adjustable Charge Voltage from 3.8V to 4.6V
- External and Internal Thermal Protection
- Safety Timer Secondary Termination
- LED Indicator Outputs
- Detects Power Outage and Switches Between Normal Power and Backup Battery
- Adjustable High-Efficiency Synchronous Buck Regulator with Skip Mode at Light Loads
- Low-Power Consumption in Discharge Mode
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Applications/Uses
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Key Specifications:
| Battery Chargers |
| Part Number |
Cell Chemistry |
Lithium Ion Cells |
Protected VIN
(V) |
Charging VIN
(V) |
Charge Rate Set by |
Max. ICHG
(A) |
Charge Termination |
Charge Regulation |
Oper. Temp.
(°C) |
Package/Pins |
Smallest Available Pckg.
(mm2) |
Budgetary Price |
| max |
max |
≥ |
max w/pins |
See Notes |
| DS2731 |
|
1 |
13.2 |
13.2 |
Resistor |
1.5 |
Min. Charge Current |
Switchmode |
-20 to +70 |
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63.7 |
$5.18 @1k |
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See All Battery Chargers (70)
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Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific prices and delivery, please see the price and availability page or contact an authorized distributor.
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| Battery Backup Circuits |
| Part Number |
Reset Thresh.
(V) |
ICC
(µA) |
Features |
Oper. Temp.
(°C) |
Package/Pins |
Smallest Available Pckg.
(mm2) |
Budgetary Price |
| max |
max w/pins |
See Notes |
| DS2731 |
2.5 to 3.3 |
150 |
| Adjustable Reset Input | | Internal FET/Transistor | | Stand Alone | | Thermal Die Regulation | | Thermistor Input | | Timer |
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-20 to +70 |
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63.7 |
$5.18 @1k |
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See All Battery Backup Circuits (86)
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Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific prices and delivery, please see the price and availability page or contact an authorized distributor.
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Diagram
Typical Operating Circuit
More Information
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Information Index
Rev 1;
2009-01-28
This page last modified: 2009-09-01
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