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| 型号： | LT3437EFE#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 13/28页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK ADJ 0.5A 16TSSOP |
| 标准包装： | 2,500 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 1.25 V ~ 54 V |
| 输入电压： | 3.3 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： | 带卷 (TR) |
| 供应商设备封装： | 16-TSSOP-EP |
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LT3437
APPLICATIO S I FOR ATIO
voltage could be unacceptable. Table 2 shows some
typical solid tantalum surface mount capacitors.
Table 2. Surface Mount Solid Tantalum Capacitor ESR
and Ripple Current
is high enough at the switching frequency, output ripple
voltage (although smaller for a ceramic output capacitor)
may still affect the proper operation of the regulator. A
filter capacitor C F in parallel with the R C /C C network, along
E CASE SIZE
AVX TPS
D CASE SIZE
AVX TPS
C CASE SIZE
AVX TPS
ESR MAX ( ? )
0.1 to 0.3
0.1 to 0.3
0.2
RIPPLE CURRENT (A)
0.7 to 1.1
0.7 to 1.1
0.5
with a small feedforward capacitor C FB , is suggested to
control possible ripple at the V C pin. The LT3437 can be
stabilized using a 100 μ F ceramic output capacitor and V C
component values of C C = 1500pF, R C = 25k, C F = 330pF
and C FB =27pF.
OUTPUT RIPPLE VOLTAGE
V OUT ( V IN – V OUT )
( V IN )( )( ) f
Manyengineershaveheardthatsolidtantalumcapacitors
are prone to failure if they undergo high surge currents.
This is historically true, and type TPS capacitors are
specially tested for surge capability, but surge ruggedness
is not a critical issue with the output capacitor. Solid
tantalum capacitors fail during very high turn-on surges
which do not occur at the output of regulators. High
discharge surges, such as when the regulator output is
dead shorted, do not harm the capacitors.
Unlike the input capacitor RMS, ripple current in the
output capacitor is normally low enough that ripple cur-
rent rating is not an issue. The current waveform is
Figure 3 shows a typical output ripple voltage waveform
for the LT3437. Ripple voltage is determined by the
impedance of the output capacitor and ripple current
through the inductor. Peak-to-peak ripple current through
the inductor into the output capacitor is:
I P-P =
L
For high frequency switchers the ripple current slew rate
is also relevant and can be calculated from:
= IN
triangularwithatypicalvalueof30mA RMS .Theformulato
calculate this is:
di
dt
V
L
Output capacitor ripple current (RMS)
Peak-to-peak output ripple voltage is the sum of a triwave
0 . 29 ( V OUT )( IN OUT
I RIPPLE ( RMS ) =
V – V
( L )( f )( V IN )
) = I P-P
12
created by peak-to-peak ripple current times ESR and a
square wave created by parasitic inductance (ESL) and
ripple current slew rate. Capacitive reactance is assumed
to be small compared to ESR or ESL.
( )( ) ( ) dt di
( 3 . 3 )( 12 – 3 . 3 )
( ) ( )( ) 3
I P-P = = 0 . 120 A
= = 0 . 12 e 6
CERAMIC CAPACITORS
Higher value, lower cost ceramic capacitors are now
becoming available. They are generally chosen for their
good high frequency operation, small size and very low
ESR (effective series resistance). Low ESR reduces output
ripple voltage but also removes a useful zero in the loop
frequency response, common to tantalum capacitors. To
compensate for this, a resistor R C can be placed in series
with the V C compensation capacitor C C (Figure 10). Care
must be taken, however, since this resistor sets the high
frequency gain of the error amplifier, including the gain at
the switching frequency. If the gain of the error amplifier
V RIPPLE = I P-P ESR + ESL
Example: with V IN = 12V, V OUT = 3.3V, L = 100 μ H, ESR =
0.075 ? , ESL = 10nH:
12 100 e ? 6 200 e
di 12
dt 100 e – 6
V RIPPLE = (0.120A)(0.075) + (10e – 9)(0.12e6)
= 0.009 + 0.0012 = 10.2mV P-P
3437fc
13
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT3437HFE | 制造商:LINER 制造商全称:Linear Technology 功能描述:High Voltage 500mA, 200kHz Step-Down Switching Regulator with 100μA Quiescent Current |
| LT3437HFE#PBF | 功能描述:IC REG BUCK 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 |
| LT3437HFE#TRPBF | 功能描述:IC REG BUCK 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 |
| LT3437IDD | 制造商:Linear Technology 功能描述:SP-SWREG/Monolithic, 60V, 500mA, 200kHz Step-down Converter w/ BurstMode |
| LT3437IDD#PBF | 功能描述:IC REG BUCK ADJ 0.5A 10DFN 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 |
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