- 您现在的位置：买卖IC网 > PDF目录20886 > LTC3217EUD#PBF (Linear Technology)IC LED DRVR FLASH TORCH 16QFN PDF资料下载
参数资料
| 型号： | LTC3217EUD#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 9/12页 |
| 文件大小： | 0K |
| 描述： | IC LED DRVR FLASH TORCH 16QFN |
| 标准包装： | 121 |
| 拓扑： | PWM，升压（升压），切换式电容器（充电泵） |
| 输出数： | 4 |
| 内部驱动器： | 是 |
| 类型 - 主要： | 闪灯/白光 |
| 类型 - 次要： | 白色 LED |
| 频率： | 600kHz ~ 1.15MHz |
| 电源电压： | 2.9 V ~ 4.5 V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-WFQFN 裸露焊盘 |
| 供应商设备封装： | 16-QFN-EP（3x3） |
| 包装： | 管件 |
| 工作温度： | -40°C ~ 85°C |
LTC3217
APPLICATIONS INFORMATION
V BAT , CPO Capacitor Selection
The style and value of the capacitors used with the LTC3217
determine several important parameters such as regulator
control loop stability, output ripple, charge pump strength
and minimum start-up time.
To reduce noise and ripple, it is recommended that low
equivalent series resistance (ESR) ceramic capacitors are
used for both CV BAT and C CPO . Tantalum and aluminum
capacitors are not recommended due to high ESR.
The value of C CPO directly controls the amount of output
ripple for a given load current. Increasing the size of C CPO
will reduce output ripple at the expense of higher start-up
current. The peak-to-peak output ripple of the 1.5x mode
is approximately given by the expression:
current will be relatively constant while the charge pump
is either in the input charging phase or the output charging
phase but will drop to zero during the clock non-overlap
times. Since the non-overlap time is small (~25ns), these
missing “notches” will result in only a small perturbation
on the input power supply line. Note that a higher ESR
capacitor such as tantalum will have higher input noise
due to the higher ESR. Therefore, ceramic capacitors are
recommended for low ESR. Input noise can be further
reduced by powering the LTC3217 through a very small
series inductor as shown in Figure 4. A 10nH inductor
will reject the fast current notches, thereby presenting a
nearly constant current load to the input power supply.
For economy, the 10nH inductor can be fabricated on the
PC board with about 1cm (0.4") of PC board trace.
I RIPPLEP -P =
I OUT
( 3 f OSC ? C CPO )
(4)
V BAT
Where f OSC is the LTC3217 oscillator frequency or typically
850kHz and C CPO is the output storage capacitor.
The output ripple in 2x mode is very small due to the fact
that load current is supplied on both cycles of the clock.
Both style and value of the output capacitor can signi?cantly
affect the stability of the LTC3217. As shown in the Block
Diagram, the LTC3217 uses a control loop to adjust the
strength of the charge pump to match the required output
current. The error signal of the loop is stored directly on
the output capacitor. The output capacitor also serves as
the dominant pole for the control loop. To prevent ringing
or instability, it is important for the output capacitor to
maintain at least 1μF of capacitance over all conditions.
In addition, excessive output capacitor ESR will tend to
degrade the loop stability. The ESR of the output capacitor
should be <100mΩ. Multilayer ceramic chip capacitors
typically have exceptional ESR performance. MLCCs
combined with a tight board layout will result in very
good stability. As the value of C CPO controls the amount
of output ripple, the value of CV BAT controls the amount of
ripple present at the input pin (V BAT ). The LTC3217 input
LTC3217
GND
3217 F04
Figure 4. 10nH Inductor Used for Input Noise Reduction
(Approximately 1cm of Board Trace)
Flying Capacitor Selection
Warning: Polarized capacitors such as tantalum or
aluminum should never be used for the ?ying capaci-
tors since their voltage can reverse upon start-up of the
LTC3217. Ceramic capacitors should always be used for
the ?ying capacitors.
The ?ying capacitors control the strength of the charge
pump. In order to achieve the rated output current it is
necessary to have at least 1.6μF of capacitance for each
of the ?ying capacitors. Capacitors of different materials
lose their capacitance with higher temperature and voltage
at different rates. For example, a ceramic capacitor made
of X7R material will retain most of its capacitance from
–40°C to 85°C whereas a Z5U or Y5V style capacitor will
lose considerable capacitance over that range. Z5U
3217fa
9
相关PDF资料 |
PDF描述 |
|---|---|
| LTC3210EUD-1#PBF | IC LED DRIVR WHITE BCKLGT 16-QFN |
| P51-200-S-B-MD-4.5V-000-000 | SENSOR 200PSI 1/8-27NPT .5-4.5V |
| P51-1000-S-S-D-4.5V-000-000 | SENSOR 1000PSI 1/4-18NPT .5-4.5V |
| P51-1000-A-D-M12-4.5OVP-000-000 | SENSOR 1000PSI 7/16-20UNF 4.5V |
| P51-15-S-T-I36-20MA-000-000 | SENSOR 15PSIS 7/16 4-20 MA |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3218 | 制造商:LINER 制造商全称:Linear Technology 功能描述:400mA Single Wire Camera LED Charge Pump |
| LTC3218EDDB#PBF | 制造商:Linear Technology 功能描述:DP-Charge Pump/LED Driver, CUT TAPE 400mA, Single Wire Camera LED Charge Pump |
| LTC3218EDDB#TRMPBF | 功能描述:IC LED DRVR FLASH TORCH 10DFN RoHS:是 类别:集成电路 (IC) >> PMIC - LED 驱动器 系列:- 标准包装:6,000 系列:- 恒定电流:- 恒定电压:- 拓扑:开路漏极，PWM 输出数:4 内部驱动器:是 类型 - 主要:LED 闪烁器 类型 - 次要:- 频率:400kHz 电源电压:2.3 V ~ 5.5 V 输出电压:- 安装类型:表面贴装 封装/外壳:8-VFDFN 裸露焊盘 供应商设备封装:8-HVSON 包装:带卷 (TR) 工作温度:-40°C ~ 85°C 其它名称:935286881118PCA9553TK/02-TPCA9553TK/02-T-ND |
| LTC3218EDDB#TRPBF | 功能描述:IC LED DRVR FLASH TORCH 10DFN RoHS:是 类别:集成电路 (IC) >> PMIC - LED 驱动器 系列:- 标准包装:6,000 系列:- 恒定电流:- 恒定电压:- 拓扑:开路漏极，PWM 输出数:4 内部驱动器:是 类型 - 主要:LED 闪烁器 类型 - 次要:- 频率:400kHz 电源电压:2.3 V ~ 5.5 V 输出电压:- 安装类型:表面贴装 封装/外壳:8-VFDFN 裸露焊盘 供应商设备封装:8-HVSON 包装:带卷 (TR) 工作温度:-40°C ~ 85°C 其它名称:935286881118PCA9553TK/02-TPCA9553TK/02-T-ND |
| LTC3218EDDBPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:400mA Single Wire Camera LED Charge Pump |
发布紧急采购，3分钟左右您将得到回复。