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| 型号： | ISL6520CB-T |
| 厂商： | Intersil |
| 文件页数： | 6/11页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 8-SOIC |
| 标准包装： | 2,500 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 340kHz |
| 占空比： | 100% |
| 电源电压： | 4.5 V ~ 5.5 V |
| 降压： | 是 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | 0°C ~ 70°C |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 带卷 (TR) |
| 其它名称： | ISL6520CB-TR |
ISL6520
Figure 4 shows the circuit traces that require additional layout
consideration. Use single point and ground plane construction
for the circuits shown. Minimize any leakage current paths on
7. Estimate Phase Margin - Repeat if Necessary.
the COMP/OCSET pin and locate the resistor, R OSCET close
OSC
DRIVER
V IN
to the COMP/OCSET pin because the internal current source is
only 20 μ A. Provide local V CC decoupling between VCC and
GND pins. Locate the capacitor, C BOOT as close as practical to
Δ V OSC
PWM
COMPARATOR
-
+
DRIVER
L O
PHASE
C O
V OUT
the BOOT and PHASE pins. All components used for feedback
compensation should be located as close to the IC a practical.
ESR
+5V
ISL6520
BOOT
C BOOT
PHASE
D 1
+V IN
Q 1
L O
V OUT
Z FB
V E/A
-
+
ERROR
AMP
Z IN
REFERENCE
(PARASITIC)
VCC
+5V
Q 2
C O
DETAILED COMPENSATION COMPONENTS
COMP/OCSET
GND
C VCC
C 1
C 2
R 2
Z FB
C 3
Z IN
R 3
V OUT
FIGURE 4. PRINTED CIRCUIT BOARD SMALL SIGNAL
LAYOUT GUIDELINES
Feedback Compensation
Figure 5 highlights the voltage-mode control loop for a
synchronous-rectified buck converter. The output voltage
COMP
-
+
ISL6520
REFERENCE
FB
R 1
(V OUT ) is regulated to the Reference voltage level. The
error amplifier (Error Amp) output (V E/A ) is compared with
the oscillator (OSC) triangular wave to provide a pulse-
width modulated (PWM) wave with an amplitude of V IN at
the PHASE node. The PWM wave is smoothed by the output
filter (L O and C O ).
Modulator Break Frequency Equations
FIGURE 5. VOLTAGE-MODE BUCK CONVERTER
COMPENSATION DESIGN
The modulator transfer function is the small-signal transfer
function of V OUT /V E/A . This function is dominated by a DC
Gain and the output filter (L O and C O ), with a double pole
break frequency at F LC and a zero at F ESR . The DC Gain of
the modulator is simply the input voltage (V IN ) divided by the
peak-to-peak oscillator voltage Δ V OSC .
F LC = -------------------------------------------
F ESR = --------------------------------------------
1
2 π x LO x CO
1
2 π x ESR x C O
Compensation Break Frequency Equations
F Z1 = ------------------------------------
F P1 = ---------------------------------------------------------
2 π x R 2 x ? ---------------------- ?
F Z2 = -------------------------------------------------------
F P2 = ------------------------------------
(EQ. 4)
The compensation network consists of the error amplifier
(internal to the ISL6520) and the impedance networks Z IN
and Z FB . The goal of the compensation network is to provide
a closed loop transfer function with the highest 0dB crossing
1
2 π x R 2 x C 1
1
2 π x ( R 1 + R 3 ) x C 3
1
? C 1 x C 2 ?
? C 1 + C 2 ?
1
2 π x R 3 x C 3
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 (R 1 , R 2 ,
R 3 , C 1 , C 2 , and C 3 ) in Figure 7. Use these guidelines for
locating the poles and zeros of the compensation network:
1. Pick Gain (R 2 /R 1 ) for desired converter bandwidth.
2. Place 1 ST Zero Below Filter’s Double Pole (~75% F LC ).
3. Place 2 ND Zero at Filter ’s Double Pole.
4. Place 1 ST Pole at the ESR Zero.
5. Place 2 ND Pole at Half the Switching Frequency.
6. Check Gain against Error Amplifier ’s Open-Loop Gain.
6
(EQ. 5)
Figure 6 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 6. 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 6 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.
FN9009.6
April 3, 2007
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ISL6520CBZ | 功能描述:IC REG CTRLR BUCK PWM VM 8-SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:275kHz 占空比:50% 电源电压:18 V ~ 110 V 降压:无 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:是 工作温度:-40°C ~ 85°C 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) |
| ISL6520CBZ-T | 功能描述:IC REG CTRLR BUCK PWM VM 8-SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:275kHz 占空比:50% 电源电压:18 V ~ 110 V 降压:无 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:是 工作温度:-40°C ~ 85°C 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) |
| ISL6520CR | 功能描述:IC REG CTRLR BUCK PWM VM 16-QFN RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 85°C 封装/外壳:40-VFQFN 裸露焊盘 包装:带卷 (TR) |
| ISL6520CR-T | 功能描述:IC REG CTRLR BUCK PWM VM 16-QFN RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 85°C 封装/外壳:40-VFQFN 裸露焊盘 包装:带卷 (TR) |
| ISL6520CRZ | 功能描述:IC REG CTRLR BUCK PWM VM 16-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:275kHz 占空比:50% 电源电压:18 V ~ 110 V 降压:无 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:是 工作温度:-40°C ~ 85°C 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) |
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