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| 型号： | LTC1159CG-3.3#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 8/20页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 20-SSOP |
| 标准包装： | 66 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 250kHz |
| 占空比： | 100% |
| 电源电压： | 4 V ~ 40 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： | 0°C ~ 70°C |
| 封装/外壳： | 20-SSOP（0.209"，5.30mm 宽） |
| 包装： | 管件 |
LTC1159
LTC1159-3.3/LTC1159-5
APPLICATIO S I FOR ATIO
0.20
0.18
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
1400
1200
1000
800
600
400
200
V IN = 48V
V OUT = 5V
V IN = 24V
V IN = 12V
0
0
1
2
3
4
5
0
0
50
100
150
200
250
) )
V OUT
C T = 7.8 ? 10
MAXIMUM OUTPUT CURRENT (A)
LTC1159 ? F02
Figure 2. R SENSE vs Maximum Output Current
I BURST ≈ 15mV
R SENSE
I SC(PK) = 150mV
R SENSE
The LTC1159 automatically extends t OFF during a short
circuit to allow sufficient time for the inductor current to
decay between switch cycles. The resulting ripple current
causes the average short-circuit current I SC(AVG) to be
reduced to approximately I MAX .
L and C T Selection for Operating Frequency
The LTC1159 uses a constant off-time architecture with
t OFF determined by an external timing capacitor C T . The
value of C T is calculated from the desired continuous mode
operating frequency, f:
–5
1–
f V IN
A graph for selecting C T versus frequency including the
effects of input voltage is given in Figure 3.
As the operating frequency is increased the gate charge
losses will be higher, reducing efficiency (see Efficiency
Considerations). The complete expression for operating
FREQUENCY (kHz)
LTC1159 ? F03
Figure 3. Timing Capacitor Selection
where t OFF = 1.3 ? 10 4 ? C T
Once the frequency has been set by C T , the inductor L
must be chosen to provide no more than 0.025V/R SENSE
of peak-to-peak inductor ripple current. This results in a
minimum required inductor value of:
L MIN = 5.1 ? 10 5 ? R SENSE ? C T ? V REG
As the inductor value is increased from the minimum value,
the ESR requirements for the output capacitor are eased at
the expense of efficiency. If too small an inductor is used,
the LTC1159 may not enter Burst Mode operation and
efficiency will be severely degraded at low currents.
Inductor Core Selection
Once the minimum value for L is known, the type of
inductor must be selected. High efficiency converters
generally cannot afford the core loss found in low cost
powdered iron cores, forcing the use of more expensive
ferrite, molypermalloy or Kool M μ ? cores. Actual core loss
is independent of core size for a fixed inductor value, but
it is very dependent on the inductance selected. As induc-
tance increases, core losses go down but copper (I 2 R)
losses will increase.
Ferrite designs have very low core loss, so design goals can
concentrate on copper loss and preventing saturation.
)
1 V OUT
frequency is given by:
f= 1–
t OFF V IN
8
)
Ferrite core material saturates “hard,” which means that
inductance collapses abruptly when the peak design cur-
rent is exceeded. This results in an abrupt increase in
Kool M μ is a registered trademark of Magnetics, Inc.
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参数描述 |
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| LTC1159CG-5 | 功能描述:IC REG CTRLR BUCK PWM CM 20-SSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC1159CG-5#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 20-SSOP 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:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 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:40-VFQFN 裸露焊盘 包装:带卷 (TR) |
| LTC1159CG-5#TR | 功能描述:IC REG CTRLR BUCK PWM CM 20-SSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC1159CG-5#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 20-SSOP 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:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 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:40-VFQFN 裸露焊盘 包装:带卷 (TR) |
| LTC1159CN | 制造商:LINER 制造商全称:Linear Technology 功能描述:High Efficiency Synchronous Step-Down Switching Regulators |
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