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參數(shù)資料
| 型號： | ISL6426IVZ |
| 廠商： | INTERSIL CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Single Synchronous Buck Pulse-Width Modulation (PWM) Controller |
| 中文描述： | SWITCHING CONTROLLER, 770 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封裝： | LEAD FREE, PLASTIC, MO-153-AB, TSSOP-16 |
| 文件頁數(shù)： | 12/18頁 |
| 文件大?。?/td> | 541K |
| 代理商： | ISL6426IVZ |
12
When using the fixed 1.8V output ISL6426 option, the
internal resistor values are R1 = 3.5k
and R2 = 2.8k
,
where R1 is connected from VOUT to FB and R2 is
connected from FB to GND.
Compensation Break Frequency
Equations
Figure 8 shows an asymptotic plot of the DC-DC converter’s
gain vs frequency. The actual Modulator Gain has a high
gain peak due to the high Q factor of the output filter and is
not shown in Figure 8. Using the above guidelines should
give a Compensation Gain similar to the curve plotted. The
open loop error amplifier gain bounds the compensation
gain. Check the compensation gain at F
P2
with the
capabilities of the error amplifier. The Closed Loop Gain is
constructed on the graph of Figure 8 by adding the
Modulator Gain (in dB) to the Compensation Gain (in dB).
This is equivalent to multiplying the modulator transfer
function to the compensation transfer function and plotting
the gain. The compensation gain uses external impedance
networks Z
FB
and Z
IN
to provide a stable, high bandwidth
(BW) overall loop. A stable control loop has a gain crossing
with -20dB/decade slope and a phase margin greater than
45 degrees. Include worst-case component variations when
determining phase margin.
Component Selection Guidelines
Charge Pump Capacitor Selection
A capacitor across pins CT1 and CT2 is required to create
the proper bias voltage for the ISL6406, ISL6426 when
operating the IC from 3.3V. Selecting the proper capacitance
value is important so that the bias current draw and the
current required by the MOSFET gates do not overburden
the capacitor. A conservative approach is presented in the
following equation.
Output Capacitor Selection
An output capacitor is required to filter the output and supply
the load transient current. The filtering requirements are a
function of the switching frequency and the ripple current.
The load transient requirements are a function of the slew
rate (di/dt) and the magnitude of the transient load current.
These requirements are generally met with a mix of
capacitors and careful layout.
Modern digital ICs can produce high transient load slew
rates. High-frequency capacitors initially supply the transient
and slow the current load rate seen by the bulk capacitors.
The bulk filter capacitor values are generally determined by
the ESR (Effective Series Resistance) and voltage rating
requirements rather than actual capacitance requirements.
High-frequency decoupling capacitors should be placed as
close to the power pins of the load as physically possible. Be
careful not to add inductance in the circuit board wiring that
could cancel the usefulness of these low inductance
components. Consult with the manufacturer of the load on
specific decoupling requirements. Use only specialized
low-ESR capacitors intended for switching-regulator
applications for the bulk capacitors. The 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.
FIGURE 8. ASYMPTOTIC BODE PLOT OF CONVERTER GAIN
100
80
60
40
20
0
-20
-40
-60
F
P1
F
Z2
10M
1M
100K
10K
1K
100
10
OPEN LOOP
ERROR AMP GAIN
F
Z1
F
P2
F
LC
F
ESR
COMPENSATION
GAIN
G
FREQUENCY (Hz)
MODULATOR
GAIN
LOOP GAIN
20
V
OSC
---------------
log
20
R1
log
C
PUMP
I
--------V
I
+
CC
f
S
(
)
=
I =
V
IN
- V
OUT
f
s
x L
V
OUT
V
IN
V
OUT
=
I x ESR
x
ISL6406, ISL6426
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| ISL6406IVZ-T | Single Synchronous Buck Pulse-Width Modulation (PWM) Controller |
| ISL6426IVZ-T | Single Synchronous Buck Pulse-Width Modulation (PWM) Controller |
| ISL6406CBZ-T | Single Synchronous Buck Pulse-Width Modulation (PWM) Controller |
| ISL6426CBZ-T | Single Synchronous Buck Pulse-Width Modulation (PWM) Controller |
| ISL6406CVZ-T | Single Synchronous Buck Pulse-Width Modulation (PWM) Controller |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ISL6430CB | 制造商:Rochester Electronics LLC 功能描述:- Bulk 制造商:Intersil Corporation 功能描述: |
| ISL6430CR | 制造商:Rochester Electronics LLC 功能描述:- Bulk 制造商:Intersil Corporation 功能描述: |
| ISL6431ACB | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| ISL6431CB | 功能描述:電壓模式 PWM 控制器 For Home Gateways RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓撲結(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
| ISL6431CB-T | 功能描述:IC REG CTRLR BUCK PWM VM 8-SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標準包裝:4,000 系列:- PWM 型:電壓模式 輸出數(shù):1 頻率 - 最大:1.5MHz 占空比:66.7% 電源電壓:4.75 V ~ 5.25 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 85°C 封裝/外殼:40-VFQFN 裸露焊盤 包裝:帶卷 (TR) |
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