MAX1778, MAX1880, MAX1881, MAX1882, MAX1883, MAX1884, MAX1885 Quad-Output TFT LCD DC-DC Converters with Buffer

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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 (V_POS) and one negative output (V_NEG). 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).

Key Features

Applications/Uses

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)
- Up to +15V LDO Input
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)

	TFT LCD Desktop Monitor Panels
	TFT LCD Notebook Displays

Key Specifications: Switch-Mode DC-DC Power Supplies
Part Number	Topology	V_IN (min) (V)	V_IN (max) (V)	Number of DC-DC Outputs	Digital/VID Programmed Output	Min. Adjustable V_OUT (V)	Max. Adjustable V_OUT (V)	I_OUT (A)	Operating Current, I_CC (max) (mA)	Fixed Freq/PWM Operation	Operating Freq. (kHz)	Internal Power Switch(es)	Synchronous Rectifier	Package	Smallest Available Package (max w/pins) (mm²)	Price^**
MAX1778	Step-Up	2.7	5.5	3	No	2.7	13	0.75	1	Yes	1000	Yes	No	TSSOP/24	52	$3.62 @ 1k
MAX1880				3							1000			TSSOP/24	52	$3.51 @ 1k
MAX1881				3							500			TSSOP/24	52
MAX1882				3							500			TSSOP/24	52
MAX1883				1							1000			TSSOP/20	43
MAX1884				1							500			TSSOP/20	43
MAX1885				1							500			TSSOP/20	43
See All Switch-Mode DC-DC Power Supplies (418)

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.