参数资料
| 型号： | SC2544TSTRT |
| 厂商： | Semtech |
| 文件页数： | 9/22页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 24TSSOP |
| 标准包装： | 1 |
| PWM 型： | 电压模式 |
| 输出数： | 2 |
| 频率 - 最大： | 300kHz |
| 占空比： | 90% |
| 电源电压： | 4.5 V ~ 28 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： | 24-TSSOP（0.173"，4.40mm 宽） |
| 包装： | 标准包装 |
| 产品目录页面： | 1358 (CN2011-ZH PDF) |
| 其它名称： | SC2544TSDKR |
SC2544
POWER MANAGEMENT
Applications Information (Cont.)
Step-do
General Design Procedure for a ep-down Poo w er
Converter
I L , rms = I o 1 +
δ 2
12
.
Selection criterias and design procedures for the fol-
lowing parameters are described:
1) Output inductor ( L ) type and value
2) Output capacitor ( C o ) type and value
3) Input capacitor ( C in ) type and value
4) Power MOSFETs
5) Current sensing and limiting circuit
6) Voltage sensing circuit
7) Loop compensation network
The following step-down converter specifications are
needed:
Input voltage range: V in,min and V in,max
Input voltage ripple (peak-to-peak): D V in
Output voltage: V o
Output voltage accuracy: e
Output voltage ripple (peak-to-peak): D V o
Nominal output (load) current: I o
Maximum output current limit: I o,max
Output (load) current transient slew rate: dI o (A/ s)
Circuit efficiency: η
Inductor (L) and Ripple Current
Both step-down controllers in the SC2544 operate in
synchronous continuous-conduction mode (CCM)
regardless of the output load level. The output
inductor selection/design is based on the output DC
and transient requirements. Both output current and
voltage ripples are reduced with larger inductance
but it takes longer to change the inductor current
The followings are to be considered when choosing
inductors.
a) Inductor core material: For higher efficiency
applications above 300 KHz, ferrite, Kool-Mu and
polypermalloy materials should be used. Low-cost
powdered iron cores can be used for cost sensitive-
applications below 300 KHz but with attendant higher
core losses.
b) Select inductance value: Sometimes the calculated
inductance value is not available off-the-shelf. The
designer can choose the adjacent (larger) standard
inductance value. The inductance varies with
temperature and DC current. It is a good engineering
practice to re-evaluate the resultant current ripple
at the rated DC output current.
c) Current rating: The saturation current of the
inductor should be at least 1.5 times of the peak
inductor current under all conditions.
Output Capacitor (C o ) and V out Ripple
The output capacitor provides output current filtering
in steady state and serves as a reservoir during load
transient. The output capacitor can be modeled as
an ideal capacitor in series with its parasitic ESR and
ESL as shown in Figure 4.
during load transients. Conversely smaller inductance
results in lower DC copper losses but the AC core
Co
Lesl
Resr
losses (flux swing) and the winding AC resistance losses
are higher. A compromise is to choose the inductance
such that peak-to-peak inductor ripple-current is 20%
to 30% of the rated output load current.
Assuming that the inductor current ripple (peak-to-
Figure 4. An equivalent circuit of output .
peak) value is δ
be
* I o , the inductance value will then
If the current through the branch is i b (t), the voltage
across the terminals will then be
V o ( 1 ? D )
1
i b ( t ) dt + L esl b
L = .
δ I o f s
The peak current in the inductor becomes
v o ( t ) = V o +
t
0
C o ∫
di ( t )
dt
+ R esr i b ( t ).
(1+ δ /2)*Io
and the RMS current is
This basic equation illustrates the effects of ESR,
ESL, and C o on the output voltage.
? 2005 Semtech Corp.
10
www.semtech.com
相关PDF资料 |
PDF描述 |
|---|---|
| SC2595MLTRT | IC DDR TERMINATION REG 16-MLPQ |
| SC2596STRT | IC INTEGRTD DDRII TERM REG 8SOIC |
| SC2608BSTRT | IC REG CTRLR BUCK PWM VM 8-SOIC |
| SC283WLTRT | IC REG BUCK SYNC ADJ 1.8A 18MLPQ |
| SC286ULTRT | IC REG BUCK SYNC ADJ 4A 28MLPQ |
相关代理商/技术参数 |
参数描述 |
|---|---|
| SC2545 | 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:High Performance Wide Input Range Dual Synchronous Buck Controller |
| SC2545EVB | 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:High Performance Wide Input Range Dual Synchronous Buck Controller |
| SC2545MLTRT | 制造商:Semtech Corporation 功能描述:Controller IC |
| SC2545TSTRT | 制造商:Semtech Corporation 功能描述:Controller IC 制造商:Semtech Corporation 功能描述:DC DC Cntrlr Dual-OUT Synchronous Buck Controller/PWM DC to DC Controller 4.5V to 28V Input 24-Pin TSSOP T/R |
| SC25-500VP | 制造商:JAMECO VALUEPRO 功能描述:CABLE,SHIELDED,25 CONDUCTOR,GRAY,24AWG,500 FEET,ROUND |
发布紧急采购，3分钟左右您将得到回复。