9
FN6436.0
June 18, 2007
Applications Information
The ISL97642 provides a highly integrated multiple output
power solution for TFT-LCD applications. The system
consists of one high efficiency boost converter and two low
cost linear-regulator controllers (V
ON
and V
OFF
) with
multiple protection functions. The block diagram of the whole
part is shown in Figure 16. Table 1 lists the recommended
components.
The ISL97642 integrates an N-Channel MOSFET in boost
converter to minimize the external component counts and
cost. The V
ON
, V
OFF
linear-regulators are independently
regulated by using external resistors. To achieve higher
voltage than V
BOOST
, one or multiple stage charge pumps
may be used.
FIGURE 13. OP AMP RAIL-TO-RAIL INPUT/OUTPUT FIGURE 14. PACKAGE POWER DISSIPATION vs AMBIENT
TEMPERATURE
FIGURE 15. PACKAGE POWER DISSIPATION vs AMBIENT TEMPERATURE
Typical Performance Curves (Continued)
JEDEC JESD51-7 HIGH EFFECTIVE
THERMAL CONDUCTIVITY TEST BOARD -
QFN EXPOSED DIEPAD SOLDERED TO
PCB PER JESD51-5
3.0
2.5
2.0
1.5
1.0
0.5
0
0 255075100 150
AMBIENT TEMPERATURE (°C)
POWER DISSIPATION (W)
2.857W
JA
= 35°C/W
QFN32
12585
JEDEC JESD51-3 AND SEMI G42-88
(SINGLE LAYER) TEST BOARD
0.8
0.7
0.5
0.3
0.2
0.1
0
0 255075100 150
AMBIENT TEMPERATURE (°C)
POWER DISSIPATION (W)
12585
0.6
0.4
JA
= 125°C/W
QFN32
758mW
INPUT
OUTPUT
TIME (50µs/DIV)
TABLE 1. RECOMMENDED COMPONENTS
DESIGNATION DESCRIPTION
C
1
, C
2
, C
3
10µF, 16V X5R ceramic capacitor (1210)
TDK C3216X5R0J106K
D
1
1A 20V low leakage Schottky rectifier
(CASE 457-04)
ON SEMI MBRM120ET3
D
11
, D
12
, D
21
200mA, 30V Schottky barrier diode (SOT-23)
Fairchild BAT54S
L
1
6.8µH, 1.3A Inductor
TDK SLF6025T-6R8M1R3-PF
Q
11
200mA, 40V PNP amplifier (SOT-23)
Fairchild MMBT3906
Q
21
200mA, 40V NPN amplifier (SOT-23)
Fairchild MMBT3904
ISL97642
