- 您现在的位置：买卖IC网 > PDF目录15270 > LTC1909-8EG#TRPBF (Linear Technology)IC REG CTRLR BUCK PWM CM 28-SSOP PDF资料下载
参数资料
| 型号： | LTC1909-8EG#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 24/32页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 28-SSOP |
| 标准包装： | 2,000 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 200kHz |
| 占空比： | 90% |
| 电源电压： | 4 V ~ 36 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： | 28-SSOP（0.209"，5.30mm 宽） |
| 包装： | 带卷 (TR) |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页第13页第14页第15页第16页第17页第18页第19页第20页第21页第22页第23页当前第24页第25页第26页第27页第28页第29页第30页第31页第32页
LTC1909-8
APPLICATIO S I FOR ATIO
? = 4 . 7 A
? I L =
? 1 –
( )
I LIMIT ≥
+
4 . 7 A = 18 A
( )( ) . 1 6 ( ) ?
24 V – 1 . 5 V ? 21 . 7 A ?
? ( 1 . 6 ) ( 0 . 012 ? ) = 2 . 12 W
?
2 ?
R ON =
= 330 k
L =
? 1 ?
? = 0 . 8 μ H
( ) ( 1 . 3 ) ( 0 . 012 ? ) +
P BOT =
( )( ) ( )( )( )
sufficient capacitance to prevent the RMS current from
causing additional upstream losses in fuses or batteries.
Other losses, including C OUT ESR loss, Schottky diode D1
conduction loss during dead time and inductor core loss
generally account for less than 2% additional loss. When
making adjustments to improve efficiency, the input cur-
rent is the best indicator of changes in efficiency. If you
make a change and the input current decreases, then the
efficiency has increased. If there is no change in input
current, then there is no change in efficiency.
Checking Transient Response
The regulator loop response can be checked by looking at
the load transient response. Switching regulators take
several cycles to respond to a step in load current. When
a load step occurs, V OUT immediately shifts by an amount
equal to ? I LOAD (ESR), where ESR is the effective series
resistance of C OUT . ? I LOAD also begins to charge or
discharge C OUT generating a feedback error signal used by
the regulator to return V OUT to its steady-state value.
During this recovery time, V OUT can be monitored for
overshoot or ringing that would indicate a stability
problem. The I TH pin external components shown in
Figure 7 will provide adequate compensation for most
applications. For a detailed explanation of switching con-
trol loop theory see Application Note 76.
Design Example
As a design example, take a supply with the following
specifications: V IN = 7V to 24V (15V nominal), V OUT = 1.5V
± 100mV, I OUT(MAX) = 15A, f = 300kHz. First, calculate the
timing resistor with V ON = V OUT :
1
( 300 kHz )( 10 pF )
and choose the inductor for about 40% ripple current at
the maximum V IN :
1 . 5 V ? 1 . 5 V ?
( 300 kHz )( 0 . 4 )( 15 A ) ? 24 V ?
Selecting a standard value of 1 μ H results in a maximum
ripple current of:
1 . 5 V ? 1 . 5 V ?
( 300 kHz ) ( 1 μ H ) ? 24 V ?
Next, choose the synchronous MOSFET switch. Because
of the narrow duty cycle and large current, a single SO-8
MOSFET will have difficulty dissipating the power lost in
the switch. Choosing two IRF7811A (R DS(ON) = 0.013 ? ,
C RSS = 60pF, θ JA = 40 ° C/W) yields a nominal sense voltage
of:
V SNS(NOM) = (15A)(0.5)(1.3)(0.012 ? ) = 117mV
Tying V RNG to INTV CC will set the current sense voltage
range for a nominal value of 140mV with current limit
occurring at 186mV. To check if the current limit is
acceptable, assume a junction temperature of about 100 ° C
above a 50 ° C ambient with ρ 150 ° C = 1.6:
186 mV 1
0 . 5 0 . 012 2
and double check the assumed T J in the MOSFET:
2
P BOT = ?
24 V
T J = 50 ° C + (2.12W)(50 ° C/W) = 156 ° C
Because the top MOSFET is on for such a short time, a
single IRF7811A will be sufficient. Checking its power
dissipation at current limit with ρ 90 ° C = 1.3:
1 .5 V 2
21 . 7 A
24 V
2
1 . 7 24 V 21 . 7 A 60 pF 300 kHz
= 0 . 46 W + 0 . 38 W = 0 . 84 W
T J = 50 ° C + (0.84W)(50 ° C/W) = 92 ° C
The junction temperatures will be significantly less at
nominal current, but this analysis shows that careful
attention to heat sinking will be necessary in this circuit.
C IN is chosen for an RMS current rating of about 6A at
temperature. The output capacitors are chosen for a low
ESR of 0.005 ? to minimize output voltage changes due to
19098f
24
相关PDF资料 |
PDF描述 |
|---|---|
| LTC1435CG#TRPBF | IC REG CTRLR BUCK PWM CM 16-SSOP |
| HCM12DSAI | CONN EDGECARD 24POS R/A .156 SLD |
| HSM06DRKF | CONN EDGECARD 12POS DIP .156 SLD |
| GBM30DTKT | CONN EDGECARD 60POS DIP .156 SLD |
| GBM36DTKS | CONN EDGECARD 72POS DIP .156 SLD |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC1911EMS8-1.5#PBF | 功能描述:IC REG BUCK 1.5V 0.25A 8MSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 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:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
| LTC1911EMS8-1.5#TR | 功能描述:IC REG BUCK 1.5V 0.25A 8MSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 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:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
| LTC1911EMS8-1.5#TRPBF | 功能描述:IC REG BUCK 1.5V 0.25A 8MSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 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:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
| LTC1911EMS8-1.8 | 功能描述:IC REG BUCK 1.8V 0.25A 8MSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 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:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
| LTC1911EMS8-1.8#PBF | 功能描述:IC REG BUCK 1.8V 0.25A 8MSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:250 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V 输入电压:2.05 V ~ 6 V PWM 型:电压模式 频率 - 开关:2MHz 电流 - 输出:500mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:6-UFDFN 包装:带卷 (TR) 供应商设备封装:6-SON（1.45x1） 产品目录页面:1032 (CN2011-ZH PDF) 其它名称:296-25628-2 |
发布紧急采购，3分钟左右您将得到回复。