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| 型号： | LT3433EFE |
| 厂商： | Linear Technology |
| 文件页数： | 11/16页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK BST ADJ 0.5A 16TSSOP |
| 标准包装： | 95 |
| 类型： | 降压（降压），升压（升压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 3.3 V ~ 20 V |
| 输入电压： | 4 V ~ 60 V |
| PWM 型： | 电流模式，混合 |
| 频率 - 开关： | 200kHz |
| 电流 - 输出： | 500mA |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-TSSOP（0.173"，4.40mm）裸露焊盘 |
| 包装： | 管件 |
| 供应商设备封装： | 16-TSSOP-EP |
LT3433
APPLICATIO S I FOR ATIO
R L = Inductor series resistance
? BST = Boosted switch drive currents I VBST /I SW (in A/A)
? OUT = Grounded switch drive currents I VOUT /I SW
(in A/A)
V F1 = Switch node catch diode forward voltage
Once DC is determined, maximum output current can be
determined using current conservation on the converter
output:
Bridged Operation: I OUT(MAX) = I SW ? [1 – DC ?
(1 + ? BST + ? OUT )] – I BIAS
V F2 = Pass diode forward voltage
Buck Operation:
I OUT(MAX) = I SW ? (1 – DC ? ? BST )
I VIN = V IN quiescent input current
I IN = V IN switched current
I BIAS = V BIAS quiescent input current
R CESR = Output capacitor ESR
Operational duty cycle is a function of voltage imposed
across the switched inductance and switch on/off times.
Using the relation for change in current in an inductor:
δ I = V ? δ t/L
and putting the application variables into the above rela-
tion yields:
δ I ON(BRIDGED) = (DC/f O ? L)[V IN – I SW ? (R SWH + R SWL
+ R L )]
δ I ON(BUCK) = (DC/f O ? L)[V IN – V OUT – V F2 – I SW
? (R SWH + R L + R ESR )]
δ I OFF = [(1 – DC)/f O ? L][V OUT + V F1 + V F2 – I SW
? (R L + R ESR )]
Current conservation in an inductor dictates δ I ON = δ I OFF ,
so plugging in the above relations and solving for DC yields:
DC (BRIDGED) = [V OUT + V F1 + V F2 – I SW ? (R L + R ESR )]/
[V IN – I SW ? (R SWH + R SWL + 2R L + R ESR ) + V OUT +
V F1 + V F2 ]
DC (BUCK) = [V OUT + V F1 + V F2 – I SW ? (R L + R ESR )]/
[V IN – I SW ? (R SWH + 2R L + 2R ESR ) + V F1 ]
In order to solve the above equations, inductor ripple
current ( ? I) must be determined so I SW can be calculated.
? I follows the relation:
? I = (V OUT + V F1 + V F2 – I SW ? R L )(1 – DC)/(L ? f O )
As ? I is a function of DC and vice-versa, the solution is
iterative. Seed ? I and solve for DC. Using the resulting
value for DC, solve for ? I. Use the resulting ? I as the new
– I BIAS
P IN = P OUT + P LOSS , where P LOSS = P SWON + P SWOFF + P IC ,
corresponding to the power loss in the converter. P IC is the
quiescent power dissipated by the LT3433. P SWON is the
loss associated with the power path during the switch on
interval, and P SWOFF is the PowerPath TM loss associated
with the switch off interval.
P LOSS equals the sum of the power loss terms:
P VIN = V IN ? I VIN
P BIAS = V OUT ? I BIAS
P SWON(BRIDGED) = DC ? [I SW 2 ? (R SWH + R SWL + R L )
+ I SW ? V OUT ? ( ? BST + ? OUT ) + R CESR ? I OUT2 ]
P SWON(BUCK) = DC ? [I SW 2 ? (R SWH + R L ) + I SW ?
V OUT ? ? BST + R CESR ? (I SW ? (1 – ? BST ) – I BIAS –
I OUT ) 2 ]
P SWOFF = (1 – DC) ? [I SW ? (V F1 + V F2 ) + I SW2 ? R L +
R CESR ? (I SW – I BIAS – I OUT ) 2 ]
Efficiency (E) is described as P OUT /P IN , so:
Efficiency = {1 + (P VIN + P BIAS + P SWON + P SWOFF )/P OUT } –1
Empirical determination of converter capabilities is ac-
complished by monitoring inductor currents with a cur-
rent probe under various input voltages and load currents.
Decreasing input voltage or increasing load current re-
sults in an inductor current increase. When peak inductor
currents reach the switch current limit value, maximum
output current is achieved. Limiting the inductor currents
to the LT3433 specified W/C current limit of 0.5V (cold)
will allow margin for operating limit variations. These
limitations should be evaluated at the operating tempera-
ture extremes required by the application to assure robust
performance.
seed value and repeat. The calculated value for DC can be
used once the resulting ? I is close (<1%) to the seed value.
PowerPath is a trademark of Linear Technology Corporation
3433f
11
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| LT3433EFE#PBF | 功能描述:IC REG BUCK BST ADJ 0.5A 16TSSOP 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 |
| LT3433EFE#TR | 功能描述:IC REG BUCK BST ADJ 0.5A 16TSSOP 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:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LT3433EFE#TRPBF | 功能描述:IC REG BUCK BST ADJ 0.5A 16TSSOP 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:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LT3433EFEPBF | 制造商:Linear Technology 功能描述:DC-DC Converter Step-Up/Down 60V TSSOP16 |
| LT3433IFE | 功能描述:IC REG BUCK BST ADJ 0.5A 16TSSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 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:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
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