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参数资料
| 型号： | ISL6426CB |
| 厂商： | INTERSIL CORP |
| 元件分类： | 稳压器 |
| 英文描述： | Triple 3-Input Positive-NAND Gates 14-SOIC -40 to 85 |
| 中文描述： | SWITCHING CONTROLLER, 770 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封装： | PLASTIC, MS-012-AC, SOIC-16 |
| 文件页数： | 3/18页 |
| 文件大小： | 541K |
| 代理商： | ISL6426CB |
11
power nodes. Use copper-filled polygons on the top and
bottom circuit layers for the phase nodes. Use the remaining
printed circuit layers for small signal wiring. The wiring traces
from the GATE pins to the MOSFET gates should be kept
short and wide enough to easily handle the 1A of drive
current. The switching components should be placed close
to the ISL6406, ISL6426 first. Minimize the length of the
connections between the input capacitors, CIN, and the
power switches by placing them nearby. Position both the
ceramic and bulk input capacitors as close to the upper
MOSFET drain and islands 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. Position the bypass capacitor, CBP, close to
the VCC pin with a via directly to the ground plane. Place
the PWM converter compensation components close to the
FB and COMP pins. The feedback resistors for both
regulators should also be located as close as possible to
the relevant FB pin with vias tied straight to the ground
plane as required.
Feedback Compensation
Figure 7 highlights the voltage-mode control loop for a
synchronous-rectified buck converter. The output voltage
(VOUT) is regulated to the Reference voltage level. The error
amplifier (Error Amp) output (VE/A) is compared with the
oscillator (OSC) triangular wave to provide a pulse-width
modulated (PWM) wave with a peak amplitude of VIN at the
PHASE node. The PWM wave is smoothed by the output
filter (L and CO).The modulator transfer function is the
small-signal transfer function of VOUT/VE/A. This function is
dominated by a DC Gain and the output filter (LO and CO),
with a double pole break frequency at FLC and a zero at
FESR. The DC Gain of the modulator is simply the input
voltage (VIN) divided by the peak-to-peak oscillator voltage,
VOSC.
Modulator Break Frequency Equations
The compensation network consists of the error amplifier
(internal to the ISL6406, ISL6426) and the impedance
networks ZIN and ZFB.The goal of the compensation
network is to provide a closed-loop transfer function with the
highest 0dB crossing frequency (f 0dB ) and adequate phase
margin. Phase margin is the difference between the closed
loop phase at f 0dB and 180 degrees.
The equations below relate the compensation network’s
poles, zeros and gain to the components (R1, R2, R3, C1, C2
poles and zeros of the compensation network:
1. Pick gain (R2/R1) for desired converter bandwidth.
2. Place first zero below filter’s double pole (~75% FLC).
3. Place second zero at filter’s double pole.
4. Place first pole at the ESR zero.
5. Place second pole at half the switching frequency.
6. Check gain against error amplifier’s open-loop gain.
7. Estimate phase margin—repeat if necessary.
FIGURE 7. VOLTAGE-MODE BUCK CONVERTER
COMPENSATION DESIGN
VOUT
REFERENCE
LO
CO
ESR
VIN
VOSC
ERROR
AMP
PWM
DRIVER
(PARASITIC)
ZFB
+
-
REFERENCE
R1
R3
R2
C3
C1
C2
COMP
VOUT
FB
ZFB
ISL6406, ISL6426
ZIN
COMPARATOR
DRIVER
DETAILED COMPENSATION COMPONENTS
PHASE
VE/A
+
-
+
-
ZIN
OSC
fLC
1
2
Π L
OCO
-----------------------------
=
fESR
1
2
Π ESR
() C
O
()
----------------------------------------
=
ISL6406, ISL6426
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ISL6426CR | 制造商:Rochester Electronics LLC 功能描述:- Bulk 制造商:Intersil Corporation 功能描述: |
| ISL6426CV | 制造商:Rochester Electronics LLC 功能描述:- Bulk 制造商:Intersil Corporation 功能描述: |
| ISL6426IB | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| ISL6426IB-T | 制造商:Rochester Electronics LLC 功能描述:- Tape and Reel |
| ISL6426IR | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
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