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HIP6500CB(1999) Просмотр технического описания (PDF) - Intersil

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HIP6500CB Datasheet PDF : 15 Pages
First Prev 11 12 13 14 15
HIP6500
d
+12VIN
+5VSB
CHF1
CSS
CBULK1
VOUT1
C12V
12V
SS
C5VSB
5VSB
5VDLSB
5VDL
CIN
Q4
VOUT5
3V3SB
CBULK5
CHF5
Q2
CHF3
VOUT3
CBULK3
3V3DLSB
HIP6500
3V3DL
DLA
5V
Q3
CBULK4
VCLK
VSEN2
3V3 GND DRV2
Q5
+5VIN
VOUT2 CHF2
Q1 CBULK2
CHF4
+3.3VIN
KEY
ISLAND ON POWER PLANE LAYER
ISLAND ON CIRCUIT/POWER PLANE LAYER
VIA CONNECTION TO GROUND PLANE
FIGURE 12. PRINTED CIRCUIT BOARD ISLANDS
A multi-layer printed circuit board is recommended. Figure
12 shows the connections of most of the components in the
converter. Note that the individual capacitors each could
represent numerous physical capacitors. Dedicate one solid
layer for a ground plane and make all critical component
ground connections through vias placed as close to the
component terminal as possible. Dedicate another solid
layer as a power plane and break this plane into smaller
islands of common voltage levels. Ideally, the power plane
should support both the input power and output power
nodes. Use copper filled polygons on the top and bottom
circuit layers to create power islands connecting the filtering
components (output capacitors) and the loads. Use the
remaining printed circuit layers for small signal wiring.
Component Selection Guidelines
Output Capacitors Selection
The output capacitors for all outputs should be selected to
allow the output voltage to meet the dynamic regulation
requirements of active state operation (S0, S1). The load
transient for the various microprocessor system’s
components may require high quality capacitors to supply
the high slew rate (di/dt) current demands. Thus, it is
recommended that the output capacitors be selected for
transient load regulation, paying attention to their parasitic
components (ESR, ESL).
Also, during the transition between active and sleep states,
there is a short interval of time during which none of the
power pass elements are conducting - during this time the
output capacitors have to supply all the output current. The
output voltage drop during this brief period of time can be
easily approximated with the following formula:
V O U T
=
IOUT
×
E
S
RO
U
T
+
C-----O--t--t-U----T-
, where
VOUT - output voltage drop
ESROUT - output capacitor bank ESR
IOUT - output current during transition
COUT - output capacitor bank capacitance
tt - active-to-sleep or sleep-to-active transition time (10µs typ.)
The output voltage drop is heavily dependent on the ESR
(equivalent series resistance) of the output capacitor bank,
the choice of capacitors should be such as to maintain the
output voltage above the lowest allowable regulation level.
VCLK (VOUT4) Output Capacitors Selection
The output capacitor for the VCLK linear regulator provides
loop stability. Figure 13 outlines a capacitance vs. equivalent
series resistance envelope. For stable operation and
optimized performance, select a COUT4 capacitor or
combination of capacitors with characteristics within the
shown envelope.
10
1.0
0.1
0.01
10
100
CAPACITANCE (µF)
FIGURE 13. COUT4 OUTPUT CAPACITOR
1000
Input Capacitors Selection
The input capacitors for an HIP6500 application have to
have a sufficiently low ESR as to not allow the input voltage
to dip excessively when energy is transferred to the output
capacitors. If the ATX supply does not meet the
specifications, certain imbalances between the ATX’s
outputs and the HIP6500’s regulation levels could have as a
result a brisk transfer of energy from the input capacitors to
12

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