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MAX1778, MAX1880, MAX1881, MAX1882, MAX1883, MAX1884, MAX1885
Quad-Output TFT LCD DC-DC Converters with Buffer
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Status
Active: In Production.
Description
The MAX1778/MAX1880–MAX1885 multiple-output
DC-DC converters provide the regulated voltages required by active matrix thin-film transistor (TFT) liquid crystal displays (LCD) in a low-profile TSSOP package. One high-power step-up converter and two low-power charge pumps convert the 2.7V to 5.5V input voltage into three independent output voltages. A built-in linear regulator and VCOM buffer complete the power-supply requirements.
The main step-up converter accurately generates an externally set output voltage up to 13V that can supply the display's row/column drivers. The converter's high switching frequency and current-mode PWM architecture provide fast transient response and allow the use of small low-profile inductors and ceramic capacitors. The low-power BiCMOS control circuitry and internal 14V switch (0.35≈ N-channel MOSFET) enable efficiencies up to 91%.
The dual low-power charge pumps (MAX1778/ MAX1880/MAX1881/MAX1882 only) independently regulate one positive output (VPOS) and one negative output (VNEG). These low-power outputs use external diode and capacitor stages (as many stages as required) to regulate output voltages up to +40V and -40V. A unique control scheme minimizes output ripple as well as capacitor sizes for both charge pumps.
A resistor-programmable, 40mA, low-dropout linear regulator (MAX1778/MAX1881/MAX1883/MAX1884 only) provides preregulation or postregulation for any of the supplies. For higher current applications, an external transistor can be added. Additionally, the VCOM buffer provides a high current output that is ideal for driving the capacitive backplane of TFT LCD panels. The VCOM buffer's output voltage is preset with an internal 50% resistive-divider or can be externally adjusted for other voltages.
The MAX1778/MAX1880–MAX1885 are protected against output undervoltage and thermal overload conditions by a latched fault detection circuit that shuts down the device. All devices are available in the ultra-thin TSSOP package (1.1mm max height).
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Data Sheet
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An evaluation kit is available: MAX1778EVKIT
Key Features
- 500kHz/1MHz Current-Mode PWM Step-Up Regulator
- Up to +13V Main High-Power Output
- ±1% Accurate
- High Efficiency (91%)
- Dual Regulated Charge-Pump Outputs (MAX1778/MAX1880/MAX1881/MAX1882 only)
- Up to +40V Positive Charge-Pump Output
- Up to -40V Negative Charge-Pump Output
- Low-Dropout 40mA Linear Regulator (MAX1778/MAX1881/MAX1883/MAX1884 only)
- Optional Higher Current with External Transistor
- 2.7V to 5.5V Input Supply
- Internal Supply Sequencing and Soft-Start
- Power-Ready Output
- Adjustable Fault-Detection Latch
- Thermal Protection (+160°C)
- 0.1µA Shutdown Current
- 0.7mA IN Quiescent Current
- Ultra-Small External Components
- Thin TSSOP Package (1.1mm max height)
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Applications/Uses
- TFT LCD Desktop Monitor Panels
- TFT LCD Notebook 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) |
Inverting Outputs |
Package/Pins |
Smallest Available Pckg.
(mm2) |
Budgetary Price |
| min |
max |
min |
max |
≥ |
≤ |
max w/pins |
See Notes |
| MAX1778 |
Step-Up |
Shutdown |
| Current Limit | | Fixed Freq./PWM | | Internal Pwr. FETs | | Soft Start |
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2.7 |
5.5 |
2.7 |
13 |
0.75 |
0.75 |
1000 |
1 |
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52.4 |
$3.91 @1k |
| MAX1880 |
1000 |
1 |
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52.4 |
$3.78 @1k |
| MAX1881 |
500 |
1 |
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52.4 |
$1.61 @1k |
| MAX1882 |
500 |
1 |
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52.4 |
- |
| MAX1883 |
1000 |
- |
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45.2 |
- |
| MAX1884 |
500 |
- |
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45.2 |
- |
| MAX1885 |
500 |
- |
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45.2 |
- |
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See All Multifunction PMICs (97)
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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
Didn't Find What You Need?
Information Index
Document Ref.: 19-1979
Rev 1;
2005-09-20
This page last modified: 2007-07-24
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