MAX1543ETP+ Maxim Integrated Products, MAX1543ETP+ Datasheet - Page 13

• 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

(2.5V rising, 2.35V falling, typ) to ensure that the input
voltage is high enough for reliable operation. The
150mV (typ) hysteresis prevents supply transients from
causing a restart. Once the input voltage exceeds the
UVLO threshold, startup begins. When the input volt-
age falls below the UVLO threshold, the controller turns
off the N-channel MOSFET, the switch control block
turns off Q1, and the operational amplifier outputs float.
For the MAX1543, the switch control block also turns off
Q2 and turns on Q3 when the input voltage falls below
the UVLO threshold (Figure 4).
The MAX1542 internal oscillator is preset to 1.2MHz. The
internal oscillator frequency is pin programmable for the
MAX1543. Connect FREQ to ground or leave it uncon-
nected for 640kHz operation and connect it to V
1.2MHz operation. FREQ has a 5µA (typ) pulldown current.
Figure 2. MAX1543 Typical Application Circuit
______________________________________________________________________________________
Oscillator Frequency (FREQ)
220pF
10µF
C11
2.6V TO 5.5V
C1
G_OFF
-7V AT 20mA
V
IN
R8
100kΩ
C10
33nF
TFT LCD DC-to-DC Converter with
C2
0.1µF
FREQ
COMP
CTL
SRC
COM
DRN
DEL
PGND
IN
MAX1543
D2
4.7µF
L1
IN
0.1µF
C3
LX
AGND
POS1
POS2
NEG1
OUT1
NEG2
OUT2
for
SUP
FB
0.1µF
C5
D1
Once the soft-start routine is complete, if the output of
the main regulator is below the fault detection threshold,
the MAX1542/MAX1543 activate the fault timer. If the
fault condition continuously exists throughout the fault
timer duration, the MAX1542/MAX1543 set the fault
latch, which shuts down the device. After removing the
fault condition, cycle the input voltage (IN) below V
to clear the fault latch and reactivate the device.
The MAX1542/MAX1543 digital soft-start period dura-
tion is 14ms (typ). During this time, the MAX1542/
MAX1543 directly limit the peak inductor current, allow-
ing from zero up to the full current-limit value in eight
equal current steps (I
is available after output voltage reaches the full regula-
tion threshold (which terminates soft-start), or after the
soft-start timer expires.
R5
40kΩ
R6
40kΩ
Operational Amplifiers
0.1µF
C4
D3
75kΩ
R3
40kΩ
R4
40kΩ
R1
D4
R2
13.7kΩ
C6
0.1µF
4.7µF
C8
BACKPLANE
C7
0.1µF
TO VCOM
LIM
+22V AT 20mA
+8V AT 250mA
C9
4.7µF
/8). The maximum load current
G_ON
V
MAIN
Digital Soft-Start
Fault Protection
UVLO
13