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MAX1843
2.7A, 1MHz, Low-Voltage, Step-Down Regulator with Internal Synchronous Rectification in TQFN Package
2.7A, 1MHz, Internal Switch Step Down Regulator
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Status
Active: In Production.
Description
The MAX1843 constant-off-time, pulse-width modulated (PWM) step-down DC-DC converter is ideal for use in 5V and 3.3V to low-voltage conversion necessary in notebook and subnotebook computers. This device features an internal PMOS power switch and internal synchronous rectification for high efficiency and reduced component count. An external Schottky diode is not required. The internal 90mΩ power switch and 70mΩ nMOS synchronous-rectifier switch easily deliver continuous load currents up to 2.7A. The MAX1843 produces a preset +2.5V, +1.8V, or +1.5V output voltage or an adjustable output from +1.1V to VIN. It achieves efficiencies as high as 95%.
The MAX1843 uses a unique current-mode, constant-off-time, PWM control scheme, which includes Idle Mode™ to maintain high efficiency during light-load operation. The programmable constant-off-time architecture sets switching frequencies up to 1MHz, allowing the user to optimize performance trade-offs between efficiency, output switching noise, component size, and cost. The MAX1843 features an adjustable soft-start to limit surge currents during startup, a 100% duty-cycle mode for low dropout operation, and a low-power shutdown mode that disconnects the input from the output and reduces supply current below 1µA. The MAX1843 is available in a 28-pin TQFN package with an exposed backside pad.
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Data Sheet
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Key Features
- ±1% Output Accuracy
- Up to 1MHz Switching Frequency
- 95% Efficiency
- Internal pMOS/nMOS Switches
- 90mΩ/70mΩ On-Resistance at VIN = +4.5V
- 110mΩ/80mΩ On-Resistance at VIN = +3V
- Output Voltage
- +2.5V, +1.8V, or +1.5V Pin Selectable
- +1.1V to VIN Adjustable
- +3V to +5.5V Input Voltage Range
- 350µA Operating Supply Current
- < 1µA Shutdown Supply Current
- Programmable Constant-Off-Time Operation
- Idle Mode Operation at Light Loads
- Thermal Shutdown
- Adjustable Soft-Start Inrush Current Limiting
- 100% Duty Cycle During Low-Dropout Operation
- Output Short-Circuit Protection
- 28-Pin TQFN Package
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Applications/Uses
- 5V or 3.3V to Low-Voltage Conversion
- Chipset Supplies
- CPU I/O Ring
- Notebook and Subnotebook Computers
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Key Specifications:
| Step-Down Switching Regulators |
| Part Number |
VIN
(V) |
VIN
(V) |
VOUT
(V) |
VOUT
(V) |
Preset VOUT
(V) |
Max. IOUT
(A) |
Max. IOUT
(A) |
Output Adjust. Method |
DC-DC Outputs |
Oper. Freq.
(kHz) |
Package/Pins |
Smallest Available Pckg.
(mm2) |
Budgetary Price |
| min |
max |
min |
max |
≥ |
≤ |
max w/pins |
See Notes |
| MAX1843 |
3 |
5.5 |
1.1 |
5.5 |
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2.7 |
2.7 |
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1 |
1000 |
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26 |
$3.97 @1k |
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See All Step-Down Switching Regulators (284)
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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
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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| MAX1843EGI
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Active |
QFN;28 pin;26 mm²
Outline Drawing:21-0091 (PDF)
Land Pattern: 90-0278 (PDF)
Use pkgcode/variation: G2855-2*
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-40°C to +85°C
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RoHS/Lead-Free: No
Materials Analysis |
| MAX1843EGI-T
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Active |
QFN;28 pin;26 mm²
Outline Drawing:21-0091 (PDF)
Land Pattern: 90-0278 (PDF)
Use pkgcode/variation: G2855-2*
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-40°C to +85°C
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RoHS/Lead-Free: No
Materials Analysis |
| MAX1843ETI+
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Active |
TQFN;28 pin;26 mm²
Outline Drawing:21-0140 (PDF)
Land Pattern: 90-0026 (PDF)
Use pkgcode/variation: T2855+6*
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-40°C to +85°C
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RoHS/Lead-Free: Lead Free
Materials Analysis |
| MAX1843ETI+T
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Active |
TQFN;28 pin;26 mm²
Outline Drawing:21-0140 (PDF)
Land Pattern: 90-0026 (PDF)
Use pkgcode/variation: T2855+6*
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-40°C to +85°C
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RoHS/Lead-Free: Lead Free
Materials Analysis |
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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| MAX1742, MAX1842 |
1A/2.7A, 1MHz, Step-Down Regulators with Synchronous Rectification and Internal Switches |
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Didn't Find What You Need?
Information Index
Document Ref.: 19-1986
Rev 2;
2006-05-16
This page last modified: 2007-06-13
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