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参数资料
| 型号： | EL7566DRE-EVAL |
| 厂商： | Intersil |
| 文件页数： | 12/14页 |
| 文件大小： | 0K |
| 描述： | DEMO BOARD FOR EL7566 |
| 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： | 6A |
| 输入电压： | 3 ~ 6 V |
| 稳压器拓扑结构： | 降压 |
| 频率 - 开关： | 500kHz |
| 板类型： | 完全填充 |
| 已供物品： | 板 |
| 已用 IC / 零件： | EL7566 |
EL7566
( V IN – V O ) × V O
V IN × Δ I L × F S
R OUT = --------
C C = 1.5 × C OUT × ----------------
( V IN – V O ) × V O
V IN × Δ I L × F S
I O F C × 2 × π × ( ESR + R OUT ) × C OUT
GM PWM × GM EA
INDUCTOR
The NMOS positive current limit is set at about 8A. For
optimal operation, the peak-to-peak inductor current ripple
Δ I L should be less than 1A. The following equation gives the
inductance value:
L = --------------------------------------------
The peak current the inductor sees is:
2
Δ I L
I LPK = I O + --------
When inductor is chosen, it must be rated to handle the peak
current and the average current of I O .
OUTPUT CAPACITOR
Output voltage ripple and transient response are the
predominant factors when choosing the output capacitor.
Initially, output capacitance should be sized with an ESR to
satisfy the output ripple Δ V O requirement:
Δ V O = Δ I L × ESR
When a step load change, Δ I O , is applied to the converter,
the initial voltage drop can be approximated by ESR* Δ I O .
The output voltage will continue to drop until the control loop
begins to correct the output voltage error. Increasing the
output capacitance will lessen the impact of load steps on
output voltage. Increasing loop bandwidth will also reduce
output voltage deviation under step load conditions. Some
experimentation with converter bandwidth and output
filtering will be necessary to generate a good transient
response (Reference Figure 15).
As with the input capacitor, it is recommended to use X5R or
X7R type of ceramic capacitors. SPCAP or POSCAP type
Polymer capacitors can also be used for the low ESR and
high capacitance requirements of these converters.
Generally, the AC current rating of the output capacitor is not
a concern because the RMS current is only 1/8 of Δ I L .
LOOP COMPENSATION
Current-mode control in system forces the inductor current
to be proportional to the error signal. This has the advantage
of eliminating the double pole response of the output filter,
and reducing complexity in the overall loop compensation. A
simple Type 1 compensator is adequate to generate a
stable, high-bandwidth converter. The compensation resister
is decided by:
------------
R C = VFB × -------------------------------------------------------------------------------------------------
12
where:
? GM PWM is the transconductance of the PWM comparator,
GM PWM = 120S
V O
I O
? ESR is the ESR of the output capacitor
? C OUT is output capacitance
? GM EA is the transconductance of the error amplifier,
GM EA = 120μS
? F C is the intended crossover frequency of the loop. For
best performance, set this value to about one-tenth of the
switching frequency.
? Once R C is chosen, C C is decided by:
R OUT
R C
Design Example
A 5V to 2.5V converter with a 6A load requirement.
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., 3A.
Panasonic EEFUD0J101XR is rated at 3.3A, 6.3V, meeting
the above criteria.
2. Choose the inductor. Set the converter switching
frequency at 500kHz:
L = --------------------------------------------
Δ I L = 1A yields 2.3μH. Leave some margin and choose
L = 2.7μH. Coilcraft's DO3316P-272HC has the required
current rating.
3. Choose the output capacitor
L = 2.7μH yields about 1A inductor ripple current. If 25mV of
ripple is desired, C OUT 's ESR needs to be less than 25m Ω .
Panasonic's EEFUD0G151XR 150μF has an ESR of 12m Ω
and is rated at 4V.
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 = 10.5k Ω and C C = 8900pF, round to standard value of
8200pF.
FN7102.7
May 8, 2006
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相关代理商/技术参数 |
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| EL7566DRE-T13 | 功能描述:IC REG BUCK SYNC ADJ 6A 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 |
| EL7566DRE-T7 | 功能描述:IC REG BUCK SYNC ADJ 6A 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 |
| EL7566DREZ | 功能描述:直流/直流开关调节器 EL7566DREZ 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 |
| EL7566DREZ-T13 | 功能描述:直流/直流开关调节器 EL7566DREZ 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 |
| EL7566DREZ-T7 | 功能描述:直流/直流开关调节器 EL7566DREZ 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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