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参数资料
| 型号： | EL7554IRE-EVAL |
| 厂商： | Intersil |
| 文件页数： | 12/14页 |
| 文件大小： | 0K |
| 描述： | DEMO BOARD FOR EL7554 |
| 标准包装： | 1 |
| 主要目的： | DC/DC，步降 |
| 输出及类型： | 1，非隔离 |
| 输出电压： | 1.8V |
| 电流 - 输出： | 4A |
| 输入电压： | 3 ~ 6 V |
| 稳压器拓扑结构： | 降压 |
| 频率 - 开关： | 600kHz |
| 板类型： | 完全填充 |
| 已供物品： | 板 |
| 已用 IC / 零件： | EL7554 |
EL7554
( V IN – V O ) × V O
V IN × Δ I L × F S
π × F C × I OUT
R C = 2 × R OUT × ----------------
output capacitor with the ESR to satisfy the output ripple
Δ V O requirement:
Δ V O = Δ I L × ESR
When output has a step load change Δ I O , the initial voltage
drop is ESR* Δ I O . Then V O will drop even further before the
loop has the chance to respond. The higher the output
capacitance, the lower the voltage drop is. Also, higher loop
bandwidth will generate less voltage drop. Experiment with
the transient response (see Figure 15) to determine the final
values of output capacitance.
Like the input capacitor, it is recommended to use X5R or
X7R type of ceramic capacitors, or SPCAP or POSCAP type
of Polymer capacitors for the low ESR and high capacitance.
Generally, the AC current rating of the output capacitor is not
a concern because the RMS current is only 1/ √ 12 of Δ I L .
This is easily satisfied.
LOOP COMPENSATION
Current mode converter forces the inductor current
proportional to the error signal, thus gets rid of the 2nd order
effect formed by the inductor and output capacitor. The PWM
comparator and the inductor form an equivalent
transconductance amplifier. So, a simple Type 1
compensator is good enough to generate a high bandwidth
stable converter. The compensation capacitor and resister
are decided by:
V FB × GM PWM × GM EA
C C = -----------------------------------------------------------------
C OUT
C C
where:
Design Example
A 5V to 1.8V converter at 4A is needed.
1. Choose the input capacitor
The input capacitor or combination of capacitors has to be
able to take about 1/2 of the output current, e.g., 2A. TDK’s
C3216X5RIA106M is rated at 2.7A, 6.3V, meeting the above
criteria using 2 generators less input voltage ripple.
2. Choose the inductor. Set the converter switching
frequency at 600kHz:
L = --------------------------------------------
Δ I L = 1A yields 1.72μH. Leave some margin and choose
L = 2.2μH. TDK RLF7030-2R2M5R4 has the required
current rating.
3. Choose the output capacitor
L = 2.2μH yields about 0.9A inductor ripple current. 47μF
ceramic capacitor has less than 5m Ω of ESR easily
satisfying by the requirement. ESR is not the only factor
deciding the output capacitance. As discussed earlier, output
voltage droops less with more capacitance when converter is
in load transient. Multiple iterations may be needed before
final components are chosen.
4. Loop compensation
50kHz is the intended crossover frequency. With the
conditions R C and C C are calculated as:
R C = 2.32k Ω and C C = 0.018pF
For convenience, Table 3 lists the compensation values for
frequently used output voltages.
TABLE 3. COMPENSATION VALUES
R OUT = ----------------
? GM PWM is the transconductance of the PWM comparator,
GM PWM = 120s
V OUT
I OUT
? V OUT output voltage
? I OUT output current
? C OUT is output capacitance
? GM EA is the transconductance of the error amplifier,
GM EA = 120μs
V O (V)
3.3
2.5
1.8
1.5
1.2
1
0.8
R C (k Ω )
4.22
3.24
2.32
1.91
1.54
1.27
1.02
C C (μF)
0.018
0.018
0.018
0.018
0.018
0.018
0.018
? F C is the intended crossover frequency of the loop. For
best performance, set this value to about one-tenth of the
switching frequency.
12
FN7360.5
November 5, 2007
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相关代理商/技术参数 |
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| EL7554IRE-T13 | 功能描述:IC REG BUCK SYNC ADJ 4A 28HTSSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:1 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:3.3V 输入电压:4.5 V ~ 24 V PWM 型:- 频率 - 开关:- 电流 - 输出:125mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-6 包装:Digi-Reel® 供应商设备封装:SOT-6 其它名称:MAX1836EUT33#TG16DKR |
| EL7554IRE-T7 | 功能描述:IC REG BUCK SYNC ADJ 4A 28HTSSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:1 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:3.3V 输入电压:4.5 V ~ 24 V PWM 型:- 频率 - 开关:- 电流 - 输出:125mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-6 包装:Digi-Reel® 供应商设备封装:SOT-6 其它名称:MAX1836EUT33#TG16DKR |
| EL7554IREZ | 功能描述:直流/直流开关调节器 LDFREE 7554 6 AMP DC:DC STP DWNG RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| EL7554IREZT13 | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:Monolithic 4 Amp DC-DC Step-Down Regulator |
| EL7554IREZ-T13 | 功能描述:直流/直流开关调节器 LDFREE EL7554 6 AMP DC:DC STP DWNG RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
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