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參數(shù)資料
| 型號(hào)： | NCP5005 |
| 廠商： | ON SEMICONDUCTOR |
| 英文描述： | Compact Backlight LED Boost Driver(背光LED升壓驅(qū)動(dòng)器) |
| 中文描述： | 緊湊型背光LED升壓驅(qū)動(dòng)器（背光的LED升壓驅(qū)動(dòng)器） |
| 文件頁數(shù)： | 6/23頁 |
| 文件大?。?/td> | 239K |
| 代理商： | NCP5005 |
NCP5005
http://onsemi.com
6
Basically, the chip operates with two cycles:
Cycle #1: time t1, the energy is stored into the inductor
Cycle #2: time t2, the energy is dumped to the load
The POR signal sets the flipflop and the first cycle takes
place. When the current hits the peak value, defined by the
error amplifier associated to the loop regulation, the
flipflop resets, the NMOS is deactivated and the current
is dumped into the load. Since the timings depend on the
environment, the internal timer limits the toff cycle to
320 ns (typical), making sure the system operates in a
continuous mode to maximize the energy transfer.
Figure 4. Basic DCDC Operation
First StartUp
Normal Operation
I
L
0 mA
Ids
0 mA
Io
0 mA
Iv
Ipeak
t
t
t
t1
t2
Based on the data sheet, the current flowing into the
inductor is bounded by two limits:
Ipeak Value: Internally fixed to 350 mA typical
Iv Value: Limited by the fixed Toff time built in the
chip (320 ns typical)
The system operates in a continuous mode as depicted in
Figure 4 and t
1
and t
2
times can be derived from basic
equations. (Note: The equations are for theoretical analysis
only, they do not include the losses.)
L
E *dt
(eq. 1)
Let V
bat
= E, then:
t1
(Ip
Iv) *L
Vbat
(eq. 2)
t2
(Ip
Vo
Iv) *L
Vbat
(eq. 3)
Since t
2
= 320 ns typical and Vo = 21 V maximum, then
(assuming a typical V
bat
= 3.0 V):
I
t2 *(Vo
Vbat)
L
(eq. 4)
Imax
320 ns *(213.0)
22 H
261 mA
Of course, from a practical stand point, the inductor must
be sized to cope with the peak current present in the circuit
to avoid saturation of the core. On top of that, the ferrite
material shall be capable to operate at high frequency
(1.0 MHz) to minimize the Foucault’s losses developed
during the cycles.
The operating frequency can be derived from the
electrical parameters. Let V = Vo V
bat
, rearranging
Equation 1:
ton
dI *L
E
(eq. 5)
Since toff is nearly constant (according to the 320 ns
typical time), the dI is constant for a given load and
inductance value. Rearranging Equation 5 yields:
ton
V*dt
L
*L
E
(eq. 6)
Let E = V
bat
, and Vopk = output peak voltage, then:
ton
(Vopk
Vbat) *dt
Vbat
(eq. 7)
Finally, the operating frequency is:
f
1
ton
toff
(eq. 8)
The output power supplied by the NCP5005 is limited to
one watt: Figure 5 shows the maximum power that can be
delivered by the chip as a function of the output voltage.
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參數(shù)描述 |
|---|---|
| NCP5005GEVB | 功能描述:電源管理IC開發(fā)工具 NCP5005 EVAL BRD RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評(píng)估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| NCP5005SNT1G | 功能描述:LED照明驅(qū)動(dòng)器 ANA WHITE LED DRIVER RoHS:否 制造商:STMicroelectronics 輸入電壓:11.5 V to 23 V 工作頻率: 最大電源電流:1.7 mA 輸出電流: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SO-16N |
| NCP5006 | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:AC-DC Offline Switching Controllers/Regulators |
| NCP5006_06 | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:Compact Backlight LED Boost Driver |
| NCP5006EVB | 功能描述:LED 照明開發(fā)工具 ANA WHITE LED DRIVER EVB RoHS:否 制造商:Fairchild Semiconductor 產(chǎn)品:Evaluation Kits 用于:FL7732 核心: 電源電壓:120V 系列: 封裝: |
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