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| 型号： | ADP1828ACPZ-R7 |
| 厂商： | Analog Devices Inc |
| 文件页数： | 20/36页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 20LFCSP |
| 标准包装： | 1,500 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 720kHz |
| 占空比： | 93% |
| 电源电压： | 3 V ~ 20 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 ~ 125°C |
| 封装/外壳： | 20-WFQFN 裸露焊盘，CSP |
| 包装： | 带卷 (TR) |
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ADP1828
During a load step transient on the output, the output capacitor
supplies the load until the control loop has a chance to ramp the
inductor current. This initial output voltage deviation, due to a
change in load, is dependent on the output capacitor charac-
teristics. Again, usually the capacitor ESR dominates this
response, and the ΔV OUT in Equation 6 can be used with the
load step current value for ΔI L .
SELECTING THE MOSFETS
The conduction losses may need an adjustment to account
for the MOSFET R DSON variation with temperature. Note that
MOSFET R DSON increases with increasing temperature. The
MOSFET data sheet should list the thermal resistance of the
package, θ JA , along with a normalized curve of the temperature
coefficient of the R DSON . For the power dissipation estimated in
Equation 10, calculate the MOSFET junction temperature rise
over the ambient temperature of interest:
The choice of MOSFET directly affects the dc-to-dc converter
T J = T A + θ JA P D
(11)
performance. The MOSFET must have low on resistance to
reduce I 2 R losses and low gate charge to reduce transition losses.
In addition, the MOSFET must have low thermal resistance to
ensure that the power dissipated in the MOSFET does not result
in excessive MOSFET die temperature.
The high-side MOSFET carries the load current during on-time
and usually carries most of the transition losses of the converter.
Typically, the lower the MOSFET’s on resistance, the higher the
gate charge and vice versa. Therefore, it is important to choose a
high-side MOSFET that balances the two losses. The conduction
loss of the high-side MOSFET is determined by the equation
Then, calculate the new R DSON from the temperature coefficient
curve and the R DSON specification at 25°C. An alternate method
to calculate the MOSFET R DSON at a second temperature, T J , is
R DSON @ T J = R DSON @ 25°C (1 + T C ( T J ? 25°C)) (12)
where T C is the temperature coefficient of the MOSFET’s R DSON ,
and its typical value is 0.004/°C.
Then the conduction losses can be recalculated and the proce-
dure iterated until the junction temperature calculations are
relatively consistent.
The synchronous rectifier, or low-side MOSFET, carries the
P C ? ( I LOAD ) 2 R DSON ? ? OUT
?
?
? V
? V IN
?
?
(7)
inductor current when the high-side MOSFET is off. The low-
side MOSFET tran sition loss is small and can be neglected in
the calculation. For high input voltage and low output voltage,
where:
P C is the conduction power loss.
R DSON is the MOSFET on resistance.
The gate charging loss is approximated by the equation
the low-side MOSFET carries the current most of the time.
Therefore, to achieve high efficiency, it is critical to optimize
the low-side MOSFET for low on resistance. In cases where the
power loss exceeds the MOSFET rating or lower resistance is
required than is available in a single MOSFET, connect multiple
P G ? V PV Q G f SW
where:
(8)
low-side MOSFETs in parallel. T he equation for low-side MOSFET
power loss is
P G is the gate charging loss power.
V PV is the gate driver supply voltage.
Q G is the MOSFET total gate charge.
f SW is the converter switching frequency.
The high-side MOSFET transition loss is approximated by the
equation
? V ?
P LS ? ( I LOAD ) 2 R DSON ? 1 ? OUT ?
? V IN ?
where:
P LS is the total low-side MOSFET power loss.
R DSON is the total on resistance of the low-side MOSFET(s).
(13)
P T =
2
V IN I LOAD ( t R + t F ) f SW
(9)
Check the gate charge losses of the synchronous rectifier using
Equation 8 to be sure it is reasonable. If multiple low-side
MOSFETs are used in parallel, then use the parallel combina-
where:
P T is the high-side MOSFET switching loss power.
t R is the MOSFET rise time.
t F is the MOSFET fall time.
The total power dissipation of the high-side MOSFET is the
sum of all the previous losses, or
P HS ? P C + P G + P T
(10)
tion of the on resistances for determining RDSON to solve this
equation.
where P HS is the total high-side MOSFET power loss.
Rev. C | Page 20 of 36
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ADP1828-BL1-EVZ | 制造商:Analog Devices 功能描述:BLANK ADISIMPOWER EVAL ADP1828 - Boxed Product (Development Kits) |
| ADP1828-BL2-EVZ | 制造商:Analog Devices 功能描述:BLANK ADISIMPOWER EVAL ADP1828 - Boxed Product (Development Kits) |
| ADP1828HC-EVALZ | 功能描述:BOARD EVALUATION ADP1828HC RoHS:是 类别:编程器，开发系统 >> 评估板 - DC/DC 与 AC/DC（离线）SMPS 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:1 系列:True Shutdown™ 主要目的:DC/DC，步升 输出及类型:1，非隔离 功率 - 输出:- 输出电压:- 电流 - 输出:1A 输入电压:2.5 V ~ 5.5 V 稳压器拓扑结构:升压 频率 - 开关:3MHz 板类型:完全填充 已供物品:板 已用 IC / 零件:MAX8969 |
| ADP1828LC-EVALZ | 功能描述:BOARD EVALUATION ADP1828LC RoHS:是 类别:编程器，开发系统 >> 评估板 - DC/DC 与 AC/DC（离线）SMPS 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:1 系列:True Shutdown™ 主要目的:DC/DC，步升 输出及类型:1，非隔离 功率 - 输出:- 输出电压:- 电流 - 输出:1A 输入电压:2.5 V ~ 5.5 V 稳压器拓扑结构:升压 频率 - 开关:3MHz 板类型:完全填充 已供物品:板 已用 IC / 零件:MAX8969 |
| ADP1828YRQZ-R7 | 功能描述:IC REG CTRLR BUCK PWM VM 20-QSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 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 ~ 125°C 封装/外壳:24-WQFN 裸露焊盘 包装:带卷 (TR) |
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