ISL6529 Datasheet, PDF (17/19 Pages) Intersil Corporation – Dual Regulator.Synchronous Rectified Buck PWM and Linear Power Controller

ISL6529, ISL6529A
However, if logic-level transistors or transistors with low
V_GS(on) are used, close attention to layout guidelines should
be exercised, as the low gate threshold could lead to some
shoot-through despite counteracting circuitry present aboard
the ISL6529.
N-Channel MOSFET Transistor Selection
The main criteria for selection of the linear regulator pass
transistor is package selection for efficient removal of heat.
Select a package and heatsink that maintains the junction
temperature below the rating with a maximum expected
ambient temperature.
The power dissipated in the linear regulator is:
P_LINEAR ≅ I_O × (V_IN – V_OUT)
(EQ. 18)
where I_O is the maximum output current and V_OUT is the
nominal output voltage of the linear regulator.
References
Intersil documents are available on the web at
http://www.intersil.com.
[1] Technical Brief, Intersil Corporation, TB417,
http://www.intersil.com/data/tb/tb417.pdf
ISL6529 Converter Application Circuit
+3.3V
C7
1000µF
L2
1µH
+5V
+12V
C6
470µF
C8
4.7µF
C5
C15
1µF
1µF
Q3
VOUT2
(1A)
R13
1.0kΩ
R5
C4
470pF
R12
6.8kΩ
5VCC
12VCC _UGATE
DRIVE2
ISL6529
ISL6529A
LGATE
COMP
2.5V
4.64kΩ
FB2
GND
FB
PGND
C14
1µF
C12
1500µF
R6
2.15kΩ
Q1 L1
Q2 4.7µH
C9
470µF
C1
47nF
R2
10.7kΩ
C2
1.2nF
R1
1.0kΩ
VOUT1
(6A)
1.6V
C10
1µF
Q1, Q2
Q3
L1
L2
IRF7313
MTD3055V
919AS-4R7M
919AS-1R0N
IR
Fairchild
TOKO
TOKO
R4
1.0kΩ
R3
C3
10Ω 47nF
FIGURE 17. POWER SUPPLY APPLICATION CIRCUIT FOR A GRAPHICS CONTROLLER
17
FN9070.5
April 12, 2005