HIP6004EVAL3 Intersil, HIP6004EVAL3 Datasheet - Page 9

• Manufacturer Part Number: HIP6004EVAL3
• Description: EVALUATION BOARD EMBED HIP6004
• Manufacturer: Intersil

Specifications of HIP6004EVAL3

• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 1.3 ~ 3.5V
• Current - Output: 14A
• Voltage - Input: 5 ~ 12V
• Regulator Topology: Buck
• Board Type: Fully Populated
• Utilized Ic / Part: HIP6004
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Power - Output: -
• Frequency - Switching: -

most cases, multiple electrolytic capacitors of small case size
perform better than a single large case capacitor.
Output Inductor Selection
The output inductor is selected to meet the output voltage
ripple requirements and minimize the converter’s response
time to the load transient. The inductor value determines the
converter’s ripple current and the ripple voltage is a function
of the ripple current. The ripple voltage and current are
approximated by the following equations:
Increasing the value of inductance reduces the ripple current
and voltage. However, the large inductance values reduce
the converter’s response time to a load transient.
One of the parameters limiting the converter’s response to a
load transient is the time required to change the inductor
current. Given a sufficiently fast control loop design, the
HIP6004 will provide either 0% or 100% duty cycle in
response to a load transient. The response time is the time
required to slew the inductor current from an initial current
value to the transient current level. During this interval the
difference between the inductor current and the transient
current level must be supplied by the output capacitor.
Minimizing the response time can minimize the output
capacitance required.
The response time to a transient is different for the
application of load and the removal of load. The following
equations give the approximate response time interval for
application and removal of a transient load:
where: I
response time to the application of load, and t
response time to the removal of load. With a +5V input
source, the worst case response time can be either at the
application or removal of load and dependent upon the
DACOUT setting. Be sure to check both of these equations
at the minimum and maximum output levels for the worst
case response time. With a +12V input, and output voltage
level equal to DACOUT, t
Input Capacitor Selection
Use a mix of input bypass capacitors to control the voltage
overshoot across the MOSFETs. Use small ceramic
capacitors for high frequency decoupling and bulk capacitors
to supply the current needed each time Q1 turns on. Place the
small ceramic capacitors physically close to the MOSFETs
and between the drain of Q1 and the source of Q2.
The important parameters for the bulk input capacitor are the
voltage rating and the RMS current rating. For reliable
operation, select the bulk capacitor with voltage and current
ratings above the maximum input voltage and largest RMS
ΔI =
t
RISE
V
=
IN
TRAN
Fs x L
V
- V
L x I
IN
OUT
- V
TRAN
is the transient load current step, t
OUT
•
V
V
OUT
IN
FALL
t
FALL
9
ΔV
is the longest response time.
OUT
=
L x I
= ΔI x ESR
V
OUT
TRAN
FALL
RISE
is the
is the
HIP6004
current required by the circuit. The capacitor voltage rating
should be at least 1.25 times greater than the maximum
input voltage and a voltage rating of 1.5 times is a
conservative guideline. The RMS current rating requirement
for the input capacitor of a buck regulator is approximately
1/2 the DC load current.
For a through hole design, several electrolytic capacitors
(Panasonic HFQ series or Nichicon PL series or Sanyo
MV-GX or equivalent) may be needed. For surface mount
designs, solid tantalum capacitors can be used, but caution
must be exercised with regard to the capacitor surge current
rating. These capacitors must be capable of handling the
surge-current at power-up. The TPS series available from
AVX, and the 593D series from Sprague are both surge
current tested.
MOSFET Selection/Considerations
The HIP6004 requires 2 N-Channel power MOSFETs.
These should be selected based upon r
requirements, and thermal management requirements.
In high-current applications, the MOSFET power dissipation,
package selection and heatsink are the dominant design
factors. The power dissipation includes two loss components;
conduction loss and switching loss. The conduction losses are
the largest component of power dissipation for both the upper
and the lower MOSFETs. These losses are distributed
between the two MOSFETs according to duty factor (see the
equations below). Only the upper MOSFET has switching
losses, since the Schottky rectifier clamps the switching node
before the synchronous rectifier turns on. These equations
assume linear voltage-current transitions and do not
adequately model power loss due the reverse-recovery of the
lower MOSFETs body diode. The gate-charge losses are
dissipated by the HIP6004 and don't heat the MOSFETs.
However, large gate-charge increases the switching interval,
t
Ensure that both MOSFETs are within their maximum junction
temperature at high ambient temperature by calculating the
temperature rise according to package thermal-resistance
specifications. A separate heatsink may be necessary
depending upon MOSFET power, package type, ambient
temperature and air flow.
Standard-gate MOSFETs are normally recommended for
use with the HIP6004. However, logic-level gate MOSFETs
can be used under special circumstances. The input voltage,
upper gate drive level, and the MOSFETs absolute gate-to-
source voltage rating determine whether logic-level
MOSFETs are appropriate.
P
Where: D is the duty cycle = V
P
SW
LOWER
UPPER
which increases the upper MOSFET switching losses.
t
F
SW
= Io
S
= Io
is the switching frequency.
is the switching interval, and
2
2
x r
x r
DS(ON)
DS(ON)
x D + 1
x (1 - D)
OUT
2
Io x V
/ V
IN
DS(ON)
IN
,
x t
SW
, gate supply
x F
S