ISL6540 Intersil Corporation, ISL6540 Datasheet - Page 15

• Manufacturer Part Number: ISL6540
• Description: Single-Phase Buck PWM Controller
• Manufacturer: Intersil Corporation

Application Guidelines
Layout Considerations
As in any high frequency switching converter, layout is very
important. Switching current from one power device to
another can generate voltage transients across the
impedances of the interconnecting bond wires and circuit
traces. These interconnecting impedances should be
minimized by using wide, short printed circuit traces. The
critical components should be located as close together as
possible using ground plane construction or single point
grounding.
Figure 7 shows the critical power components of the
converter. To minimize the voltage overshoot/undershoot
the interconnecting wires indicated by heavy lines should be
ISL6540
FIGURE 7. PRINTED CIRCUIT BOARD POWER AND
UGATE
PHASE
LGATE
PGND
GROUND PLANES OR ISLANDS
VOUT (LOCAL)
GND (LOCAL)
FIGURE 6. SIMPLIFIED UNITY GAIN DIFFERENITAL SENSING IMPLEMENTATION
V
Q2
Q1
RETURN
IN
15
800mV
VCC
C
10Ω
10Ω
IN
L
(REMOTE)
VSENSE-
O
C
O
VSEN-
V
OUT
R
C
OS
SEN
(REMOTE)
VSENSE+
VSEN+
ISL6540
R
GAIN=1
FB
V
SS
part of ground or power plane in a printed circuit board. The
components shown in Figure 8 should be located as close
together as possible. Please note that the capacitors C
and C
Locate the ISL6540 within 3 inches of the MOSFETs, Q1
and Q2. The circuit traces for the MOSFETs’ gate and
source connections from the ISL6540 must be sized to
handle up to 4A peak current.
Proper grounding of the IC is important for correct operation
in noisy environments. The PGND pin should be connected
to board ground at the source of the low side MOSFET with
a wide short trace. The GND pin should be connected to a
large copper fill under the IC which is subsequently
connected to board ground at a quite location on the board,
typically found at an input or output bulk (electrolytic)
capacitor.
VMON
C
FIGURE 8. PRINTED CIRCUIT BOARD SMALL SIGNAL
SS
SS
Z
OV/UV
COMP
O
IN
each represent numerous physical capacitors.
GND
ISL6540
LAYOUT GUIDELINES
ERROR AMP
FB
PGND
Z
FB
PHASE
C
PVCC
BOOT
BOOT
+5V
COMP
C
PVCC
D1
Q1
+V
Q2
IN
L
O
C
O
March 9, 2006
FN9214.0
V
IN
OUT