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參數(shù)資料
| 型號(hào)： | LNK305P-TL |
| 廠商： | POWER INTEGRATIONS INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 0.8 A SWITCHING REGULATOR, 70 kHz SWITCHING FREQ-MAX, PDIP8 |
| 封裝： | PLASTIC, DIP-8 |
| 文件頁(yè)數(shù)： | 11/16頁(yè) |
| 文件大?。?/td> | 142K |
| 代理商： | LNK305P-TL |
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4
LNK304-306
D
1/04
Applications Example
A 1.44 W Universal Input Buck Converter
The circuit shown in Figure 5 is a typical implementation of a
12 V, 120 mA non-isolated power supply used in appliance
control such as rice cookers, dishwashers or other white goods.
This circuit may also be applicable to other applications such as
night-lights, LED drivers, electricity meters, and residential
heating controllers, where a non-isolated supply is acceptable.
The input stage comprises fusible resistor RF1, diodes D3 and
D4, capacitors C4 and C5, and inductor L2. Resistor RF1 is a
flame proof, fusible, wire wound resistor. It accomplishes
several functions: a) Inrush current limitation to safe levels for
rectifiers D3 and D4; b) Differential mode noise attenuation; c)
Input fuse should any other component fail short-circuit
(component fails safely open-circuit without emitting smoke,
fire or incandescent material).
The power processing stage is formed by the LinkSwitch-TN,
freewheeling diode D1, output choke L1, and the output capacitor
C2. The LNK304 was selected such that the power supply
operates in the mostly discontinuous-mode (MDCM). Diode
D1 is an ultra-fast diode with a reverse recovery time (t
rr) of
approximately 75 ns, acceptable for MDCM operation. For
continuous conduction mode (CCM) designs, a diode with a t
rr
of
≤35 ns is recommended. Inductor L1 is a standard off-the-
shelf inductor with appropriate RMS current rating (and
acceptable temperature rise). Capacitor C2 is the output filter
capacitor; its primary function is to limit the output voltage
ripple. The output voltage ripple is a stronger function of the
ESR of the output capacitor than the value of the capacitor itself.
To a first order, the forward voltage drops of D1 and D2 are
identical. Therefore, the voltage across C3 tracks the output
voltage. The voltage developed across C3 is sensed and regulated
via the resistor divider R1 and R3 connected to U1’s FB pin.
The values of R1 and R3 are selected such that, at the desired
output voltage, the voltage at the FB pin is 1.65 V.
Regulation is maintained by skipping switching cycles. As the
output voltage rises, the current into the FB pin will rise. If this
exceeds I
FB then subsequent cycles will be skipped until the
current reduces below I
FB. Thus, as the output load is reduced,
more cycles will be skipped and if the load increases, fewer
cycles are skipped. To provide overload protection if no cycles
are skipped during a 50 ms period, LinkSwitch-TN will enter
auto-restart, limiting the average output power to approximately
6% of the maximum overload power. Due to tracking errors
between the output voltage and the voltage across C3 at light
load or no load, a small pre-load may be required (R4). For the
design in Figure 5, if regulation to zero load is required, then this
value should be reduced to 2.4 k
.
Key Application Considerations
LinkSwitch-TN Design Considerations
Output Current Table
Data sheet maximum output current table (Table 1) represents
the maximum practical continuous output current for both
mostly discontinuous conduction mode (MDCM) and
continuous conduction mode (CCM) of operation that can be
delivered from a given LinkSwitch-TN device under the following
assumed conditions:
1) Buck converter topology.
2) The minimum DC input voltage is
≥70 V. The value of input
capacitance should be large enough to meet this criterion.
3) For CCM operation a KRP* of 0.4.
4) Output voltage of 12 VDC.
5) Efficiency of 75%.
6) A catch/freewheeling diode with t
rr ≤75 ns is used for
MDCM operation and for CCM operation, a diode with
t
rr ≤35 ns is used.
7) The part is board mounted with SOURCE pins soldered to a
sufficient area of copper to keep the SOURCE pin temperature
at or below 100
°C.
*KRP is the ratio of ripple to peak inductor current.
RTN
12 V,
120 mA
85-265
VAC
PI-3757-112103
FB
BP
S
D
LinkSwitch-TN
C4
4.7
F
400 V
C1
100 nF
D4
1N4007
D3
1N4007
D1
UF4005
LNK304
D2
1N4005GP
C2
100
F
16 V
RF1
8.2
2 W
R1
13.0 k
1%
R3
2.05 k
1%
L2
1 mH
L1
1 mH
280 mA
C5
4.7
F
400 V
C3
10
F
35 V
R4
3.3 k
Figure 5. Universal Input, 12 V, 120 mA Constant Voltage Power Supply Using LinkSwitch-TN.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LNK306D | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:12W電源芯片LNK306D |
| LNK306DG | 功能描述:交流/直流開關(guān)轉(zhuǎn)換器 225 mA (MDCM) 360 mA (CCM) RoHS:否 制造商:STMicroelectronics 輸出電壓:800 V 輸入/電源電壓（最大值）:23.5 V 輸入/電源電壓（最小值）:11.5 V 開關(guān)頻率:115 kHz 電源電流:1.6 mA 工作溫度范圍:- 40 C to + 150 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SSO-10 封裝:Reel |
| LNK306DGTL | 制造商:POWERINT 制造商全稱:Power Integrations, Inc. 功能描述:LinkSwitch-TN Family Lowest Component Count, Energy-Effi cient Off-Line Switcher IC |
| LNK306DG-TL | 功能描述:交流/直流開關(guān)轉(zhuǎn)換器 225 mA (MDCM) 360 mA (CCM) RoHS:否 制造商:STMicroelectronics 輸出電壓:800 V 輸入/電源電壓（最大值）:23.5 V 輸入/電源電壓（最小值）:11.5 V 開關(guān)頻率:115 kHz 電源電流:1.6 mA 工作溫度范圍:- 40 C to + 150 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SSO-10 封裝:Reel |
| LNK306DN | 功能描述:交流/直流開關(guān)轉(zhuǎn)換器 225 mA (MDCM) 360 mA (CCM) RoHS:否 制造商:STMicroelectronics 輸出電壓:800 V 輸入/電源電壓（最大值）:23.5 V 輸入/電源電壓（最小值）:11.5 V 開關(guān)頻率:115 kHz 電源電流:1.6 mA 工作溫度范圍:- 40 C to + 150 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SSO-10 封裝:Reel |
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