ISL6548ACRZA Intersil, ISL6548ACRZA Datasheet - Page 12

• Manufacturer Part Number: ISL6548ACRZA
• Description: IC REG/CTLR ACPI DUAL DDR 28QFN
• Manufacturer: Intersil

Specifications of ISL6548ACRZA

• Applications: Memory, DDR/DDR2 Regulator
• Current - Supply: 7mA
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 28-QFN
• Rohs Compliant: YES
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Supply: -

FIGURE 2. PRINTED CIRCUIT BOARD POWER PLANES
12V
KEY
ATX
GND PAD
ISL6548A
VIA CONNECTION TO GROUND PLANE
ISLAND ON POWER PLANE LAYER
ISLAND ON CIRCUIT AND/OR POWER PLANE LAYER
P12V
DRIVE2_L
DRIVE2_U
VDDQ(2)
COMP4
DRIVE3
5VSBY
PHASE
LGATE
UGATE
AND ISLANDS
PWM4
VTT(2)
COMP
GNDP
FB4
FB2
FB3
FB
C
OUT2
R
R
C
C
C
C
2
6
R
2
6
BP
BP
R
10
5VSBY
12
R
R
12
4
8
R
R
C
C
11
9
1
5
C
C
3
7
R
R
5VDUAL
V
Q
1
Q
5
TT
R
R
1
2
3
7
C
OUT5
Q
L
C
3
1
C
C
Q
IN
3.3VATX
V
OUT1
OUT3
3
3.3VATX
V
DDQ
Q
ICH7
Q
Q
V
C
3
1
TT_GMCH/CPU
2
OUT4
V
DDQ
V
C
GMCH
IN
L
2
ISL6548A
the heat to move away from the IC and also ties the pad to
the ground plane through a low impedance path.
The switching components should be placed close to the
ISL6548A first. Minimize the length of the connections
between the input capacitors, C
by placing them nearby. Position both the ceramic and bulk
input capacitors as close to the upper MOSFET drain as
possible. Position the output inductor and output capacitors
between the upper and lower MOSFETs and the load.
The critical small signal components include any bypass
capacitors, feedback components, and compensation
components. Place the PWM converter compensation
components close to the FB and COMP pins. The feedback
resistors should be located as close as possible to the FB
pin with vias tied straight to the ground plane as required.
Feedback Compensation - PWM Buck Converters
Figure 3 highlights the voltage-mode control loop for a
synchronous-rectified buck converter. The output voltage
(V
amplifier output (V
triangular wave to provide a pulse-width modulated (PWM)
wave with an amplitude of V
PWM wave is smoothed by the output filter (L
∆V
OUT
FIGURE 3. VOLTAGE-MODE BUCK CONVERTER
OSC
V
) is regulated to the Reference voltage level. The error
DDQ
OSC
COMPARATOR
=
COMPENSATION DESIGN AND OUTPUT
VOLTAGE SELECTION
ERROR
AMP
DETAILED COMPENSATION COMPONENTS
V
0.8
ISL6548A
E/A
PWM
E/A
×
Z
+
-



FB
-
+
COMP
1
) is compared with the oscillator (OSC)
C
+
REFERENCE
2
REFERENCE
R
------ -
R
C
1
4
+
-
1



IN
DRIVER
DRIVER
R
Z
2
at the PHASE node. The
IN
IN
, and the power switches
FB
Z
FB
PHASE
R
(PARASITIC)
V
4
C
IN
3
L
Z
R
O
IN
1
O
R
ESR
C
3
and C
O
V
January 3, 2006
DDQ
V
FN9189.2
O
DDQ
).