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| 型号： | LT1612ES8 |
| 厂商： | Linear Technology |
| 文件页数： | 6/12页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ 0.5A 8SOIC |
| 标准包装： | 100 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 可调至 0.6V |
| 输入电压： | 2 V ~ 5.5 V |
| PWM 型： | 电流模式，混合 |
| 频率 - 开关： | 800kHz |
| 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： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 管件 |
| 供应商设备封装： | 8-SOIC |
LT1612
OPERATIO
The LT1612 employs fixed frequency, current mode con-
trol. This type of control uses two feedback loops. The
main control loop sets output voltage and operates as
follows: A load step causes V OUT and the FB voltage to be
perturbed slightly. The error amplifier responds to this
change in FB by driving the V C pin either higher or lower.
Because switch current is proportional to the V C pin
voltage, this change causes the switch current to be
adjusted until V OUT is once again satisfied. Loop compen-
sation is taken care of by an RC network from the V C pin
to ground.
Inside this main loop is another that sets current limit on
a cycle-by-cycle basis. This loop utilizes current compara-
tor A2 to control peak current. The oscillator runs at
800kHz and issues a set pulse to the flip-flop at the
beginning of each cycle, turning the switch on. With the
switch now in the ON state the SW pin is effectively
connected to V IN . Current ramps up in the inductor linearly
at a rate of (V IN – V OUT )/L. Switch current is set by the V C
pin voltage and when the voltage across R SENSE trips the
current comparator, a reset pulse will be generated and the
Layout Hints
The LT1612 switches current at high speed, mandating
careful attention to layout for proper performance. You
will not get advertised performance with careless layout.
Figure 2 shows recommended component placement for
a buck (step-down) converter. Follow this closely in your
PC layout. Note the direct path of the switching loops.
Input capacitor C1 must be placed close (< 5mm) to the IC
package. As little as 10mm of wire or PC trace from C IN to
V IN will cause problems such as inability to regulate or
oscillation.
The ground terminal of input capacitor C1 should tie close
to Pin 4 of the LT1612. Doing this reduces dI/dt in the
ground copper which keeps high frequency spikes to a
minimum. The DC/DC converter ground should tie to the
PC board ground plane at one place only, to avoid intro-
ducing dI/dt in the ground plane.
switch will be turned off. Since the inductor is now loaded
up with current, the SW pin will fly low and trigger the
R1
R2
R C
C C
1
8
SHDN
rectifier to turn on. Current will flow through the rectifier
decreasing at a rate of V OUT /L until the oscillator issues a
new set pulse, causing the cycle to repeat.
V IN
C1
2
3
4
LT1612
7
6
5
MODE
C3
If the load is light and V C decreases below A3’s trip point,
the device will enter the Burst Mode operation region (the
C2
MODE pin must be at ground or floating). In this state the
oscillator and all other circuitry except the reference and
comparator A3 are switched on and off at low frequency.
This mode of operation increases efficiency at light loads
but introduces low frequency voltage ripple at the output.
MULTIPLE
VIAs
GND
L1
V OUT
1612 F02
For continuous switching and no low frequency output
voltage ripple, pull the MODE pin high. This will disable
comparator A3 which forces the oscillator to run
Figure 2. Recommended Component Placement. Traces
Carrying High Current are Direct. Trace Area at FB Pin and V C
Pin Is Kept Low. Lead Length to Battery Should Be Kept Short
continuously.
sn1612 1612fs
6
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT1612ES8#PBF | 功能描述:IC REG BUCK SYNC ADJ 0.5A 8SOIC 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 |
| LT1612ES8#TR | 功能描述:IC REG BUCK SYNC ADJ 0.5A 8SOIC 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 |
| LT1612ES8#TRPBF | 功能描述:IC REG BUCK SYNC ADJ 0.5A 8SOIC 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 |
| LT1613 | 制造商:LINER 制造商全称:Linear Technology 功能描述:4A, 2MHz Dual Phase Step-Up DC/DC Converter in 3mm 3mm DFN |
| LT1613CS5 | 制造商:Linear Technology 功能描述:Conv DC-DC Single Step Up 0.9V to 10V 5-Pin TSOT-23 |
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