Datasheet
Multi-Output Power Supplies with VCOM Amplifier
and High-Voltage Gamma Reference for LCD TVs
MAX17126/MAX17126A
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Typical Operating Circuit
The typical operating circuit (Figure 1) of the MAX17126/
MAX17126A comprise a complete power-supply system
for TFT LCD TV panels. The circuit generates a +3.3V
logic supply, a +16V source driver supply, a +35V posi-
tive gate-driver supply, a -6V negative gate-driver supply,
and a P 0.5% high-accuracy, high-voltage gamma refer-
ence. Table 1 lists some selected components and Table
2 lists the contact information for component suppliers.
Detailed Description
The MAX17126/MAX17126A are multiple-output power
supplies designed primarily for TFT LCD TV panels. It
contains a step-down switching regulator to generate the
supply for system logic, a step-up switching regulator to
generate the supply for source driver, and two charge-
pump regulators to generate the supplies for TFT gate
drivers, a high-accuracy, high-voltage reference supply
for gamma correction. Each regulator features adjust-
able output voltage, digital soft-start, and timer-delayed
fault protection. Both the step-down and step-up regula-
tors use fixed-frequency current-mode control architec-
ture. The two switching regulators are 180N out of phase
to minimize the input ripple. The internal oscillator offers
two pin-selectable frequency options (500kHz/750kHz),
allowing users to optimize their designs based on the
specific application requirements. The step-up regu-
lator also features adjustable current limit that can
be adjusted through a resistor at the CLIM pin. The
MAX17126/MAX17126A include one high-performance
operational amplifier designed to drive the LCD back-
plane (VCOM). The amplifier features high-output cur-
rent (P 200mA), fast slew rate (45V/Fs), wide bandwidth
(20MHz), and rail-to-rail outputs. The high-accuracy,
high-voltage gamma reference has its error controlled to
within P 0.5% and can deliver more than 60mA current.
In addition, the MAX17126/MAX17126A feature a high-
voltage switch-control block, an internal 5V linear regula-
tor, a 1.25V reference output, well-defined power-up and
power-down sequences, and fault and thermal-overload
protection. Figure 2 shows the MAX17126/MAX17126A
functional diagram.
Table 1. Component List
Table 2. Operating Mode
DESIGNATION DESCRIPTION
C1–C4
10FF P Q10%, 25V X5R ceramic
capacitors (1206)
Murata GRM31CR61E106K
TDK C3216X5R1E106M
C5
22FF Q10%, 6.3V X5R ceramic capacitor
(0805)
Murata GRM21BR60J226K
TDK C2012X5R0J226K
D1, D2
Schottky diodes 30V, 3A (M-flat)
Toshiba CMS02
D3, D4, D5
Dual diodes 30V, 200mA (3 SOT23)
Zetex BAT54S
Fairchild BAT54S
L1
Inductor, 10FH, 3A, 45mI inductor
(8.3mm x 9.5mm x 3mm)
Coiltronics SD8328-100-R
Sumida CDRH8D38NP-100N (8.3mm x
8.3mm x 4mm)
L2
Inductor, 4.7FH, 3A, 24.7mI inductor
(8.3mm x 9.5mm x 3mm)
Coiltronics SD8328-4R7-R
Sumida CDRH8D38NP-4R7N (8.3mm x
8.3mm x 4mm)
SUPPLIER PHONE FAX WEBSITE
Fairchild Semiconductor 408-822-2000 408-822-2102 www.fairchildsemi.com
Sumida Corp. 847-545-6700 847-545-6720 www.sumida.com
TDK Corp. 847-803-6100 847-390-4405 www.component.tdk.com
Toshiba America Electronic Components, Inc. 949-455-2000 949-859-3963 www.toshiba.com/taec