- 您现在的位置：买卖IC网 > PDF目录14802 > LT1976EFE#PBF (Linear Technology)IC REG BUCK ADJ 1.5A 16TSSOP PDF资料下载
参数资料
| 型号： | LT1976EFE#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 13/28页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK ADJ 1.5A 16TSSOP |
| 标准包装： | 95 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 1.2 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： | 1.5A |
| 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 |
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页当前第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页第24页第25页第26页第27页第28页
LT1976/LT1976B
APPLICATIO S I FOR ATIO
V OUT ( V IN – V OUT )
I RIPPLE ( RMS ) =
capacitive loads or high input voltages can cause a high
input current surge during start-up. The soft-start func-
tion reduces input current surge by regulating switch
current via the V C pin to maintain a constant voltage ramp
rate (dV/dt) at the output. A capacitor (C1 in Figure 2) from
the C SS pin to the output determines the maximum output
dV/dt. When the feedback voltage is below 0.4V, the V C pin
will rise, resulting in an increase in switch current and
output voltage. If the dV/dt of the output causes the current
through the C SS capacitor to exceed I CSS the V C voltage is
reduced resulting in a constant dV/dt at the output. As the
feedback voltage increases I CSS increases, resulting in an
increased dV/dt until the soft-start function is defeated
with 0.9V present at the FB pin. The soft-start function
does not affect operation during normal load conditions.
However, if a momentary short (brown out condition) is
present at the output which causes the FB voltage to drop
below 0.9V, the soft-start circuitry will become active.
INPUT CAPACITOR
Step-down regulators draw current from the input supply
in pulses. The rise and fall times of these pulses are very
fast. The input capacitor is required to reduce the voltage
ripple this causes at the input of LT1976 and force the
switching current into a tight local loop, thereby minimiz-
ing EMI. The RMS ripple current can be calculated from:
I OUT
V IN
Ceramic capacitors are ideal for input bypassing. At 200kHz
switching frequency input capacitor values in the range of
4.7 μ F to 20 μ F are suitable for most applications. If opera-
tion is required close to the minimum input required by the
LT1976 a larger value may be required. This is to prevent
excessive ripple causing dips below the minimum operat-
ing voltage resulting in erratic operation.
Input voltage transients caused by input voltage steps or
by hot plugging the LT1976 to a pre-powered source such
as a wall adapter can exceed maximum V IN ratings. The
sudden application of input voltage will cause a large
the parasitic inductance of the leads. This energy will
cause the input voltage to swing above the DC level of input
power source and it may exceed the maximum voltage
rating of the input capacitor and LT1976. All input voltage
transient sequences should be observed at the V IN pin of
the LT1976 to ensure that absolute maximum voltage
ratings are not violated.
The easiest way to suppress input voltage transients is to
add a small aluminum electrolytic capacitor in parallel with
the low ESR input capacitor. The selected capacitor needs
to have the right amount of ESR to critically damp the
resonant circuit formed by the input lead inductance and
the input capacitor. The typical values of ESR will fall in the
range of 0.5 Ω to 2 Ω and capacitance will fall in the range
of 5 μ F to 50 μ F.
If tantalum capacitors are used, values in the 22 μ F to
470 μ F range are generally needed to minimize ESR and
meet ripple current and surge ratings. Care should be
taken to ensure the ripple and surge ratings are not
exceeded. The AVX TPS and Kemet T495 series are surge
rated AVX recommends derating capacitor operating volt-
age by 2:1 for high surge applications.
OUTPUT CAPACITOR
The output capacitor is normally chosen by its effective
series resistance (ESR) because this is what determines
output ripple voltage. To get low ESR takes volume, so
physically smaller capacitors have higher ESR. The ESR
range for typical LT1976 applications is 0.05 Ω to 0.2 Ω . A
typical output capacitor is an AVX type TPS, 100 μ F at 10V,
with a guaranteed ESR less than 0.1 Ω . This is a “D” size
surface mount solid tantalum capacitor. TPS capacitors
are specially constructed and tested for low ESR, so they
give the lowest ESR for a given volume. The value in
microfarads is not particularly critical and values from
22 μ F to greater than 500 μ F work well, but you cannot
cheat Mother Nature on ESR. If you find a tiny 22 μ F solid
tantalum capacitor, it will have high ESR and output ripple
voltage could be unacceptable. Table 3 shows some
typical solid tantalum surface mount capacitors.
surge of current in the input leads that will store energy in
1976bfg
13
相关PDF资料 |
PDF描述 |
|---|---|
| RBM12DRMN-S664 | CONN EDGECARD 24POS .156 WW |
| LTC3442EDE#PBF | IC REG BUCK BOOST SYNC ADJ 12DFN |
| LT8582EDKD#PBF | IC REG MULTI CONFIG ADJ 3A 24DFN |
| MAX6423XS28+T | IC MPU/RESET CIRC 2.80V SC70-4 |
| LTC3413EFE#PBF | IC REG BUCK SYNC ADJ 3A 16TSSOP |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LT1976HFE | 制造商:LINER 制造商全称:Linear Technology 功能描述:High Voltage 1.5A, 200kHz Step-Down Switching Regulator with 100μA Quiescent Current |
| LT1976HFE#PBF | 功能描述:IC REG BUCK ADJ 1.5A 16TSSOP RoHS:是 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 |
| LT1976HFE#TRPBF | 功能描述:IC REG BUCK ADJ 1.5A 16TSSOP RoHS:是 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 |
| LT1976IFE | 功能描述:IC REG BUCK ADJ 1.5A 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 |
| LT1976IFE#PBF | 功能描述:IC REG BUCK ADJ 1.5A 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 |
发布紧急采购，3分钟左右您将得到回复。