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MAX8847Y, MAX8847Z
High-Performance Negative Charge Pump for 6 White LEDs in 3mm x 3mm Thin QFN
Achieves Industry's Highest Efficiency Using a Negative Charge Pump to Independently Drive 6 White LEDs
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Status
Active: In Production.
Description
The MAX8847Y/MAX8847Z negative charge pumps drive up to 6 white LEDs with regulated constant current for display backlight applications. By utilizing an inverting charge pump and extremely low-dropout adaptive current regulators, these ICs achieve very high efficiency over the full 1-cell Li+ battery voltage range even with large LED forward voltage mismatch. The 1MHz fixed-frequency
switching allows for tiny external components. The regulation scheme is optimized to ensure low EMI and low input ripple. The MAX8847Y/MAX8847Z include
thermal shutdown, open- and short-circuit protection.
The MAX8847Y/MAX8847Z support independent LED on/off and dimming control. The MAX8847Z has PWM dimming control for LED1–LED6. The MAX8847Y has PWM dimming control for LED1–LED4 and serial-pulse dimming control for LED5 and LED6. The serial-pulse dimming ranges are pseudo-logarithmic from 24mA to
0.1mA and off in 32 steps. All devices include a temperature derating function to safely allow bright 24mA full-scale output current while automatically reducing current gradually to protect LEDs at high ambient temperatures
above +60°C.
The MAX8847Y/MAX8847Z are available in 16-pin, 3mm x 3mm thin QFN packages.
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Data Sheet
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Key Features
- Negative 1x/1.5x Charge Pump
- Adaptive Current Regulators
- Independent Voltage Supply for Each LED
- 24mA to 0.1mA Serial-Pulse Dimming (MAX8847Y)
- 24mA to 0mA PWM Dimming (MAX8847Z)
- 2% (max) LED Current Accuracy, 1% (typ) Matching
- Low 120µA Quiescent Current
- Low 0.4µA Shutdown Current
- Inrush Current Limit
- Temperature Derating Function
- 16-Pin, 3mm x 3mm Thin QFN Packages
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Applications/Uses
- Cellular Phones
- PDAs, Digital Cameras, and Camcorders
- White LED Backlighting
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Key Specifications:
| White LED Drivers |
| Part Number |
Topology |
LEDs |
Config. |
Dimming Control |
VDROPOUT
(mV) |
VCURR_SENSE
(mV) |
POUT
(W) |
ILED
(mA) |
VIN
(V) |
VIN
(V) |
ICC
(mA) |
VOUT
(V) |
Oper. Freq.
(kHz) |
Package/Pins |
| max num. of |
typ |
max |
min |
max |
max |
max |
| MAX8847 |
Charge Pump |
6 |
Parallel |
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85 |
150 |
0.6 |
24 |
2.7 |
5.5 |
0.12 |
5 |
1000 |
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See All White LED Drivers (47)
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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
Document Ref.: 19-5198
Rev 0;
2010-05-04
This page last modified: 2010-05-17
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