ISL6522A Intersil Corporation, ISL6522A Datasheet - Page 10

• Manufacturer Part Number: ISL6522A
• Description: Buck and Synchronous Rectifier Pulse-Width Modulator (PWM) Controller
• Manufacturer: Intersil Corporation

V
the bias, the gate-to-source voltage of Q1 is 7V. A logic-level
MOSFET is a good choice for Q1 and a logic-level MOSFET
can be used for Q2 if its absolute gate-to-source voltage rating
exceeds the maximum voltage applied to PV
Schottky Selection
Rectifier D2 is a clamp that catches the negative inductor
swing during the dead time between turning off the lower
MOSFET and turning on the upper MOSFET. The diode must
be a Schottky type to prevent the lossy parasitic MOSFET
body diode from conducting. It is acceptable to omit the diode
and let the body diode of the lower MOSFET clamp the
negative inductor swing, but efficiency will drop one or two
Component Selection Notes:
Q1, Q2 - Fairchild MOSFET; RFP25N05
C1-C3 - Three each 680µF 25W VDC, Sanyo MV-GX or equivalent.
C6-C9 - Four each 1000µF 6.3W VDC, Sanyo MV-GX or equivalent.
CC
CR1 - 1N4148 or equivalent.
CR2 - 3A, 40V Schottky, Motorola MBR340 or equivalent.
L1 - Core: micrometals T50-52B; winding: ten turns of 17AWG.
less the input supply. For +5V main power and +12V
ENABLE
12V
RTN
V
CC
IN
0.1µF
C13
3x 680µF
R2
1K
C1-3
R7
10K
R3
1K
SPARE
10
R1
SPARE
SS
RT
FB
C16
0.01µF
C15
3
1
6
5
1206
C12
1µF
REF
FIGURE 11. DC-DC CONVERTER APPLICATION CIRCUIT
33pF
C14
+
-
+
-
R4
SPARE
OSC
15K
CC
R5
ISL6522A
MONITOR AND
.
PROTECTION
U1
14
4
COMP
VCC
+
-
-
+
COMP
TP1
DC
for
7
ISL6522A
GND
10
13
12
11
8
9
2
OCSET
BOOT
UGATE
PHASE
PVCC
LGATE
PGND
percent as a result. The diode's rated reverse breakdown
voltage must be greater than the maximum input voltage.
ISL6522A DC-DC Converter Application
Circuit
Figure 11 shows a DC-DC converter circuit for a
microprocessor application, originally designed to employ
the HIP6006 controller. Given the similarities between the
HIP6006 and ISL6522A controllers, the circuit can be
implemented using the ISL6522A controller without any
modifications. Detailed information on the circuit, including a
complete bill of materials and circuit board description, can
be found in Application Note AN9722. See Intersil’s home
1000pF
JP1
3.01K
C19
Q1
R6
Q2
CR2
MBR
340
CR1
4148
0.1µF
C20
C17-18
2x 1µF
1206
PHASE
TP2
4x 1000µF
L1
C6-9
RTN
V
OUT