MAX1543ETP+ Maxim Integrated Products, MAX1543ETP+ Datasheet - Page 11

• Manufacturer Part Number: MAX1543ETP+
• Description: IC DC-DC CONV TFT-LCD 20-TQFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX1543ETP+

• Applications: Controller, TFT, LCD
• Voltage - Input: 2.6 ~ 5.5 V
• Number Of Outputs: 2
• Voltage - Output: 2.6 ~ 13 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 20-TQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The regulator controls the output voltage and the power
delivered to the outputs by modulating the duty cycle
(D) of the power MOSFET in each switching cycle. The
duty cycle of the MOSFET is approximated by:
The device regulates the output voltage through a com-
bination of an error amplifier, two comparators, and
several signal generators (Figure 3). The error amplifier
compares the signal at FB to 1.24V and varies the
COMP output. The voltage at COMP determines the
current trip point each time the internal MOSFET turns
on. As the load varies, the error amplifier sources or
sinks current to the COMP output accordingly to pro-
duce the inductor peak current necessary to service
the load. To maintain stability at high duty cycles, a
slope compensation signal is summed with the current-
sense signal.
The MAX1542/MAX1543 include two operational ampli-
fiers that are typically used to drive the LCD backplane
VCOM and/or the gamma correction divider string. The
operational amplifiers feature ±150mA output short-cir-
cuit current, 7.5V/µs slew rate, and 12MHz bandwidth.
The rail-to-rail inputs and outputs maximize flexibility.
Table 1. Component List
Table 2. Component Suppliers
Inductors
Sumida USA
Capacitors
TDK
Diodes
Fairchild
Toshiba
SUPPLIER
DESIGNATION
D2, D3, D4
C8, C9
C1
D1
______________________________________________________________________________________
L1
D
≈
V
MAIN
V
MAIN
Operational Amplifiers
−
V
IN
TFT LCD DC-to-DC Converter with
847-956-0666
847-803-6100
888-522-5372
949-455-2000
10µF ±10%, 6.3V X5R ceramic capacitor
4.7µF ±10%, 10V X5R ceramic capacitors
1A, 30V Schottky diode
200mA, 100V dual ultra-fast diodes
4.7µH, 1.3A inductor
PHONE
DESCRIPTION
The MAX1542/MAX1543 operational amplifiers limit
short-circuit current to ±150mA if the output is directly
shorted to SUP or AGND. In such a condition, the junc-
tion temperature of the IC rises until it reaches the ther-
mal shutdown threshold, typically +160°C. Once it
reaches this threshold, the IC shuts down and remains
inactive until IN falls below V
The operational amplifiers are typically used to drive
the LCD backplane (VCOM) or the gamma correction
divider string. The LCD backplane consists of a distrib-
uted series capacitance and resistance, a load easily
driven by the operational amplifiers. However, if the
operational amplifiers are used in an application with a
pure capacitive load, steps must be taken to ensure
stable operation.
As the operational amplifier’s capacitive load increases,
the amplifier bandwidth decreases and gain peaking
increases. A small 5Ω to 50Ω resistance placed between
OUT_ and the capacitive load reduces peaking but
reduces the amplifier gain. An alternative method of
reducing peaking is the use of a snubber circuit. A 150Ω
and 10nF (typ) shunt load, or snubber, does not continu-
ously load the output or reduce amplifier gain.
Operational Amplifiers
847-956-0702
847-803-6296
408-822-2104
949-859-3963
FAX
TDK C3216X5R0J106K
TDK C3225X5R1A475K
Toshiba CRS02
Fairchild MMBD4148SE
Sumida CLS5D11HP-4R7
Driving Pure Capacitive Loads
Short-Circuit Current Limit
www.sumida.com
www.component.tdk.com
www.fairchildsemi.com
www.toshiba.com/taec/
UVLO
.
PART
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