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MAX8798
Internal-Switch Boost Regulator with Integrated 3-Channel Scan Driver for TFT LCDs
High Integration, High Efficiency Power Management IC for LCD Displays Saves Space and Cost
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Status
Active: In Production.
Description
The MAX8798 includes a high-performance, step-up regulator; a high-speed operational amplifier; a digitally adjustable VCOM calibration device with nonvolatile memory; an I²C interface; and a high-voltage, level-shifting scan driver. The device is optimized for thin-film transistor (TFT) liquid-crystal display (LCD) applications.
The step-up DC-DC converter provides the regulated supply voltage for panel source driver ICs. The high switching frequency allows the use of ultra-small inductors and ceramic capacitors. The current-mode control architecture provides fast transient response to pulsed loads typical of source driver loads. The step-up regulator features soft-start and current limit.
The high-current operational amplifier is designed to drive the LCD backplane (VCOM). The amplifier features high output current (±150mA), fast slew rate (45V/µs), wide bandwidth (20MHz), and rail-to-rail inputs and outputs.
The programmable VCOM calibrator is externally attached to the VCOM amplifier’s resistive voltage-divider and sinks a programmable current to adjust the VCOM output-voltage level. An internal 7-bit digital-to-analog converter (DAC) controls the sink current. The DAC is ratiometric relative to BOOST and is guaranteed to be monotonic over all operating conditions. The calibrator IC includes an EEPROM to store the desired VCOM voltage level. The 2-wire I²C interface between the LCD panel and the programming circuit minimizes panel connector lead count and simplifies production equipment.
The high-voltage, level-shifting scan driver is designed to drive the TFT panel gate drivers. Its three outputs swing 65V (maximum) between +45V (maximum) and -25V (minimum) and can swiftly drive capacitive loads. To save power, the two complementary outputs are designed to allow charge sharing during state changes.
The MAX8798 is available in a 36-pin, thin QFN package with a maximum thickness of 0.8mm for ultra-thin LCD panels.
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Data Sheet
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An evaluation kit is available: MAX8798EVCMAXQU+, MAX8798EVKIT+ NOTE: This product uses the following:MAX8798 EVKIT Software
Key Features
- 1.8V to 5.5V IN Supply Voltage Range
- 1.8V to 4.0V VDD Input Voltage Range
- 1.2MHz Current-Mode Step-Up Regulator
- Fast Transient Response
- Built-In 20V, 1.9A, 150mΩ MOSFET
- High-Speed (20MHz) Operational Amplifier
- High-Voltage Drivers with Scan Logic
- +45V to -25V Outputs
- 65V (maximum) Swing
- Output Charge Sharing
- Programmable VCOM Calibrator
- 7-Bit Adjustable Current-Sink Output
- I²C Interface
- EEPROM Setting Memory
- Thermal-Overload Protection
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Applications/Uses
- LCD Monitor Panels
- Notebook Computer Displays
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Key Specifications:
| Multifunction PMICs |
| Part Number |
Primary Topology |
Monitor/Control Features |
DC-DC/Power Features |
LCD/LED/Flash/CCD Features |
VIN
(V) |
VIN
(V) |
VOUT
(V) |
VOUT
(V) |
Max. IOUT
(A) |
Max. IOUT
(A) |
Oper. Freq.
(kHz) |
Package/Pins |
Smallest Available Pckg.
(mm2) |
Budgetary Price |
| min |
max |
min |
max |
≥ |
≤ |
max w/pins |
See Notes |
| MAX8798 |
Step-Up |
| Output OVP | | Output UVP | | Serial Interface | | Shutdown |
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| Current Limit | | Fixed Freq./PWM | | Internal Pwr. FETs | | Soft Start |
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| Scan Driver | | TFT Bias | | VCOM Buffer |
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1.8 |
5.5 |
1.23 |
18 |
0.4 |
0.4 |
1200 |
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37.2 |
$2.11 @1k |
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See All Multifunction PMICs (96)
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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
Simplified Operating Circuit
Product Guides
Reliability Reports
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| Request Reliability Report for: |
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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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| MAX8798AETX+
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Active |
TQFN;36 pin;37.2 mm²
Outline Drawing:21-0141 (PDF)
Land Pattern: 90-0052 (PDF)
Use pkgcode/variation: T3666N+1*
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-40°C to +85°C
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RoHS/Lead-Free: Lead Free
Materials Analysis |
| MAX8798AETX+CAQ
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Active |
TQFN;36 pin;37.2 mm²
Outline Drawing:21-0141 (PDF)
Land Pattern: 90-0052 (PDF)
Use pkgcode/variation: T3666N+1*
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-40°C to +85°C
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RoHS/Lead-Free: Lead Free
Materials Analysis |
| MAX8798AETX+T
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|
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Active |
TQFN;36 pin;37.2 mm²
Outline Drawing:21-0141 (PDF)
Land Pattern: 90-0052 (PDF)
Use pkgcode/variation: T3666N+1*
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-40°C to +85°C
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RoHS/Lead-Free: Lead Free
Materials Analysis |
| MAX8798ETX+
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Active |
TQFN;36 pin;37.2 mm²
Outline Drawing:21-0141 (PDF)
Land Pattern: 90-0051 (PDF)
Use pkgcode/variation: T3666MN+1*
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-40°C to +85°C
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RoHS/Lead-Free: Lead Free
Materials Analysis |
| MAX8798ETX+T
|
|
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Active |
TQFN;36 pin;37.2 mm²
Outline Drawing:21-0141 (PDF)
Land Pattern: 90-0051 (PDF)
Use pkgcode/variation: T3666MN+1*
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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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Information Index
Document Ref.: 19-0971
Rev 1;
2008-08-19
This page last modified: 2009-08-26
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