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參數(shù)資料
| 型號(hào)： | HIP6002CB |
| 廠商： | HARRIS SEMICONDUCTOR |
| 元件分類(lèi)： | 穩(wěn)壓器 |
| 英文描述： | Rectifier (PWM) Controller and Output Voltage Monitor |
| 中文描述： | SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO20 |
| 文件頁(yè)數(shù)： | 9/12頁(yè) |
| 文件大?。?/td> | 211K |
| 代理商： | HIP6002CB |
9
bulk capacitor’s ESR will determine the output ripple voltage
and the initial voltage drop after a high slew-rate transient. An
aluminum electrolytic capacitor's ESR value is related to the
case size with lower ESR available in larger case sizes.
However, the Equivalent Series Inductance (ESL) of these
capacitors increases with case size and can reduce the
usefulness of the capacitor to high slew-rate transient loading.
Unfortunately, ESL is not a specified parameter. Work with your
capacitor supplier and measure the capacitor’s impedance with
frequency to select a suitable component. In 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
HIP6002 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
TRAN
is the transient load current step, t
RISE
is the
response time to the application of load, and t
FALL
is the
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
FALL
is the longest response time.
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
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
orequivalent)maybeneeded.Forsurfacemountdesigns,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 HIP6002 requires 2 N-channel power MOSFETs. These
should be selected based upon r
DS(ON)
, gate supply
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
P
UPPER
= I
O2
x r
DS(ON)
x D +1
P
LOWER
= I
O2
x r
DS(ON)
x (1 - D)
voltage-current transitions and do not adequately model
power loss due the reverse-recovery of the lower MOSFET’s
body diode. The gate-charge losses are dissipated by the
HIP6002 and don't heat the MOSFETs. However, large gate-
charge increases the switching interval, t
SW
which increases
V
OUT
=
I x ESR
I =
V
- V
-------------------------------
V
IN
---------------
t
RISE
L
IN
I
OUT
×
----------–
=
t
FALL
L
------------------------------
I
OUT
×
=
2Io x V
IN
x t
SW
x Fs
Where: D is the duty cycle = V
OUT
/V
IN
,
t
SW
is the switching interval, and
Fs is the switching frequency.
HIP6002
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參數(shù)描述 |
|---|---|
| HIP6002CB-T | 制造商:未知廠家 制造商全稱(chēng):未知廠家 功能描述:Voltage-Mode SMPS Controller |
| HIP6003 | 制造商:INTERSIL 制造商全稱(chēng):Intersil Corporation 功能描述:Buck Pulse-Width Modulator (PWM) Controller and Output Voltage Monitor |
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| HIP6003CB-T | 制造商:未知廠家 制造商全稱(chēng):未知廠家 功能描述:Voltage-Mode SMPS Controller |
| HIP6003EVAL1 | 制造商:Rochester Electronics LLC 功能描述:P PRO VRM EVALUATION BOARD - STD BUCK - Bulk 制造商:Harris Corporation 功能描述: |
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