MAX1543ETP+ Maxim Integrated Products, MAX1543ETP+ Datasheet - Page 12

• 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

A capacitor from DEL to AGND selects the switch control
block supply startup delay. After the input voltage
exceeds V
Once the capacitor voltage exceeds the turn-on thresh-
old (1.24V) COM can be connected to SRC, depending
on the state of CTL. Before startup and when IN is less
than V
charge C
The switch control input (CTL) is not activated until
V
voltage (V
TFT LCD DC-to-DC Converter with
Operational Amplifiers
Figure 1. MAX1542 Typical Application Circuit
12
DEL
______________________________________________________________________________________
exceeds the turn-on voltage (1.24V) and the input
UVLO
DEL
IN
UVLO
, DEL is internally connected to AGND to dis-
) exceeds V
. Select C
C
DEL
, a 5µA current source charges C
=
(
DELAY TIME
DEL
MAX1542 Control Block Switch
2.6V TO 5.5V
G_OFF
-7V AT 20mA
R8
100kΩ
C11
220pF
UVLO
V
IN
using the following equation:
C10
33nF
C1
10µF
Delay Control Circuit
(2.5V). Once activated,
)
0.1µF
×
C2
COMP
SRC
CTL
COM
DEL
PGND
1 24
5
.
IN
µ
A
V
MAX1542
4.7µF
L1
D2
LX
AGND
DEL
POS1
POS2
NEG1
OUT1
NEG2
OUT2
SUP
0.1µF
FB
C3
.
0.1µF
C5
D1
R5
40kΩ
0.1µF
R6
40kΩ
CTL controls the P-channel MOSFET, between COM
and SRC. A high at CTL turns on Q1 between SRC and
COM, and a low at CTL turns Q1 off (Figure 4).
The switch control input (CTL) is not activated until the
input voltage (V
exceeds the turn-on voltage (1.24V). During UVLO or
when DEL is below the turn-on threshold, COM is
pulled low to PGND through Q3 and a 1kΩ resistance.
Once activated, CTL controls the COM MOSFETs,
switching COM between SRC and DRN. A high at CTL
turns on Q1 and disables Q2. A low at CTL turns on Q2
and turns off Q1 (Figure 4).
The UVLO comparator of the MAX1542/MAX1543 com-
pares the input voltage at IN with the UVLO threshold
C4
D3
R3
40kΩ
75kΩ
R4
40kΩ
R1
D4
R2
13.7kΩ
C6
0.1µF
IN
Undervoltage Lockout (UVLO)
C8
4.7µF
) exceeds V
+22V AT 20mA
C7
0.1µF
MAX1543 Control Block Switch
G_ON
C9
4.7µF
BACKPLANE
+8V AT 250mA
TO VCOM
V
UVLO
MAIN
(2.5V) and V
DEL