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MAX745
Switch-Mode Lithium-Ion Battery-Charger
±0.75% Precision Li+ Charger Delivers 4A Without Heating
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Status
Active: In Production.
Description
The MAX745 provides all functions necessary for charging lithium-ion (Li+) battery packs. It provides a regulated charging current of up to 4A without getting hot, and a regulated voltage with only ±0.75% total error at the battery terminals. It uses low-cost, 1% resistors to set the output voltage, and a low-cost N-channel MOSFET as the power switch.
The MAX745 regulates the voltage set point and charging current using two loops that work together to transition smoothly between voltage and current regulation. The per-cell battery voltage regulation limit is set between 4V and 4.4V using standard 1% resistors, and then the number of cells is set from 1 to 4 by pin-strapping. Total output voltage error is less than ±0.75%.
For a similar device with an SMBus™ microcontroller interface and the ability to charge NiCd and NiMH cells, refer to the MAX1647 and MAX1648. For a low-cost Li+ charger using a linear-regulator control scheme, refer to the MAX846A.
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Data Sheet
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An evaluation kit is available: MAX745EVKIT
Key Features
- Charges 1 to 4 Li+ Battery Cells
- ±0.75% Voltage-Regulation Accuracy
Using 1% Resistors
- Provides up to 4A without Excessive Heating
- 90% Efficient
- Uses Low-Cost Set Resistors and
N-Channel Switch
- Up to 24V Input
- Up to 18V Maximum Battery Voltage
- 300kHz Pulse-Width Modulated (PWM) Operation Low-Noise, Small Components
- Stand-Alone Operation—No Microcontroller Needed
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Applications/Uses
- Cell Phones
- Desktop Cradle Chargers
- Handheld Instruments (PDAs, Palmtops)
- Li+ Battery Packs
- Notebook Computers
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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 |
EV Kit |
Oper. Temp.
(°C) |
Package/Pins |
Smallest Available Pckg.
(mm2) |
Budgetary Price |
| max |
max |
≥ |
max w/pins |
See Notes |
| MAX745 |
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24 |
24 |
Resistor |
4 |
| Current Limit | | Max. Voltage |
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Switchmode |
Yes |
-40 to +85 |
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57.9 |
$4.99 @1k |
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See All Battery Chargers (68)
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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
Application Notes
Reliability Reports
Software/Models
Ordering Information
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Part Number
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Free
Sample |
Buy |
Status
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Package:
TYPE PINS FOOTPRINT
DRAWING CODE/VAR *
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Temp |
RoHS/Lead-Free?
Materials Analysis
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| MAX745C/D
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Active |
Land Pattern: Not Available
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See data sheet
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| MAX745EAP
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Active |
SSOP;20 pin;57.9 mm²
Outline Drawing:21-0056 (PDF)
Land Pattern: 90-0094 (PDF)
Use pkgcode/variation: A20-1*
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-40°C to +85°C
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See data sheet
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| MAX745EAP+
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Active |
SSOP;20 pin;57.9 mm²
Outline Drawing:21-0056 (PDF)
Land Pattern: 90-0094 (PDF)
Use pkgcode/variation: A20+1*
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-40°C to +85°C
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RoHS/Lead-Free: Lead Free
Materials Analysis |
| MAX745EAP+T
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Active |
SSOP;20 pin;57.9 mm²
Outline Drawing:21-0056 (PDF)
Land Pattern: 90-0094 (PDF)
Use pkgcode/variation: A20+1*
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-40°C to +85°C
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RoHS/Lead-Free: Lead Free
Materials Analysis |
| MAX745EAP-T
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Active |
SSOP;20 pin;57.9 mm²
Outline Drawing:21-0056 (PDF)
Land Pattern: 90-0094 (PDF)
Use pkgcode/variation: A20-1*
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-40°C to +85°C
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See data sheet
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Notes:
- Other options and links for purchasing parts are listed at: http://www.maxim-ic.com/sales.
- Didn't Find What You Need? Ask our applications engineers. Expert assistance in finding parts, usually within one business day.
- Part number suffixes: T or T&R = tape and reel; + = RoHS/lead-free; # = RoHS/lead-exempt; -D = drypack; -U/+U on DS parts = cut tape. More: See Full Data Sheet or Maxim Product Naming Conventions.
- * Some packages have variations, listed on the drawing. "PkgCode/Variation" tells which variation the product uses. Note that "+", "#", "-" in the part number suffix describes RoHS status. Package drawings may show a different suffix character.
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Similar Products by Function
| MAX846A |
Cost-Saving, Multichemistry, Battery Charger System |
| MAX1647, MAX1648 |
Chemistry-Independent Battery Chargers |
| MAX1640, MAX1641 |
Adjustable-Output, Switch-Mode Current Sources with Synchronous Rectifier |
| MAX1782 |
Advanced Smart Battery-Pack Controller |
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Evaluation Kits
Products with Similar Part Numbers
Didn't Find What You Need?
Information Index
Document Ref.: 19-1182
Rev 3;
2002-09-10
This page last modified: 2007-05-31
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