MAX1513 Datasheet, PDF (13/28 Pages) Maxim Integrated Products – TFT-LCD Power-Supply Controllers

TFT-LCD Power-Supply Controllers
Typical Operating Circuit
The typical operating circuit of the MAX1513 (Figure 1) is
a complete power-supply system for TFT LCDs. The cir-
cuit generates a +15V source-driver supply, +25V and
-10V gate-driver supplies, a +3.3V logic supply for the
timing controller, a 14.7V gamma-correction string supply
and a VCOM buffer. The typical operating circuit of the
MAX1514 (Figure 2) is similar to that of the MAX1513
except the gamma-correction string supply and the
VCOM buffer have been eliminated. The input voltage
range for the IC is from +2.7V to +5.5V. The typical oper-
ating circuits’ listed load currents are available from a
+4.5V to +5.5V supply. Table 1 lists recommended com-
ponent options, and Table 2 lists the component suppli-
ers’ contact information.
Table 1. Component List
DESIGNATION
DESCRIPTION
C1
22µF ±20%, 6.3V X5R ceramic capacitor (1206)
Taiyo Yuden JMK316BJ226ML
C2
10µF ±20%, 16V POSCAP (D10)
Sanyo 16AQU10M
D1
1A, 30V Schottky diode (S-Flat)
Toshiba CRS02
D2, D3
200mA, 100V diodes (SOT23)
Fairchild MMBT4148SE
L1
2.2µH, 3.3A inductor
Sumida CLS7D16NP-2R2NC
N1
3A, 20V N-channel MOSFET (SOT23)
Fairchild FDN339AN
Q1
3A, 60V PNP bipolar transistor (SOT23)
Fairchild NZT660
Q2
200mA, 40V NPN bipolar transistor (SOT23)
Fairchild MMBT3904
Q3, Q4
200mA, 40V PNP bipolar transistors (SOT23)
Fairchild MMBT3906
Table 2. Component Suppliers
SUPPLIER
Fairchild Semiconductor
Sumida
Taiyo Yuden
TDK
Toshiba
PHONE
408-822-2000
847-545-6700
800-348-2496
847-803-6100
949-455-2000
Detailed Description
The MAX1513 and MAX1514 contain a high-perfor-
mance, step-up switching-regulator controller and three
linear-regulator controllers (two positive and one nega-
tive). The MAX1513 also includes an additional linear-reg-
ulator controller and a high-current buffer amplifier. Figure
3 shows the MAX1513/MAX1514 functional diagram.
Main Step-Up Regulator Controller
The main step-up regulator controller drives an external
N-channel power MOSFET to generate the TFT-LCD
source-driver supply. The controller employs a current-
mode, fixed-frequency PWM architecture to maximize
loop bandwidth and provide fast transient response to
pulsed loads found in source-driver applications. The
multilevel control input SDFR sets the switching fre-
quency to 430kHz, 750kHz, or 1.5MHz. The high
switching frequency allows the use of low-profile induc-
tors and ceramic capacitors to minimize the thickness
of LCD panel designs, while maintaining high efficiency
using a lossless current-sense method. The IC’s built-in
soft-start function reduces the inrush current during
startup.
The controller regulates the output voltage and the
power delivered to the output by modulating the duty
cycle (D) of the power MOSFET in each switching cycle.
The duty cycle of the MOSFET is approximated by:
D ≈ ^{VMAIN - VIN}
V_MAIN
Figure 4 shows the functional diagram of the step-up
regulator controller. The core of the controller is a multi-
input summing comparator that sums three signals: the
output-voltage error signal with respect to the reference
voltage, the current-sense signal, and the slope-com-
pensation ramp. On the rising edge of the internal
clock, the controller sets a flip-flop, which turns on the
external N-channel MOSFET, applying the input voltage
across the inductor. The current through the inductor
ramps up linearly, storing energy in its magnetic field.
Once the sum of the feedback voltage error, slope
compensation, and current-sense signals trip the multi-
FAX
408-822-2102
847-545-6720
847-925-0899
847-390-4405
949-859-3963
WEBSITE
www.fairchildsemi.com
www.sumida.com
www.t-yuden.com
www.component.tdk.com
www.toshiba.com
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