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參數(shù)資料
| 型號(hào)： | SP6138ER1-L |
| 廠商： | EXAR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 2 A SWITCHING CONTROLLER, 2800 kHz SWITCHING FREQ-MAX, QCC16 |
| 封裝： | 3 X 3 MM, LEAD FREE, MO-220VEED-4, QFN-16 |
| 文件頁(yè)數(shù)： | 2/17頁(yè) |
| 文件大?。?/td> | 958K |
| 代理商： | SP6138ER1-L |
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Oct 24-06 Rev J
SP638 Synchronous Buck Controller
2006 Sipex Corporation
LpisduetowiringandPCBtracesconnecting
input capacitors and switching MOSFETs.
For typical Lp of 2nH and Vin of 2V, di/dt
is 1A/ns. Substituting for di/dt in equation (6)
we get Qgd = 2 nC.
In selecting a package type, the main con-
siderations are cost, power/current handling
capability and space constraints. A larger
package in general offers higher power and
current handling at increased cost. Package
selection can be narrowed down by calculat-
ing the required junction-to-ambient thermal
resistance θja:
θja = {Tj(max) - Ta(max)} / P(max)........... (7)
Where: Tj(max) is the die maximum tem-
perature rating, Ta(max) is maximum ambient
temperature, and P(max) is maximum power
dissipated in the die.
It is common practice to add a guard-band
of 25C to the junction temperature rating.
Following this convention, a 150C rated
MOSFETwillbedesignedtooperateat125C
(i.e., Tj(max) = 125C). P(max) = 0.88W (from
section 4) and Ta(max) = 40C as specified in
the design example. Substituting in equation
(7) we get θja = 96.6 C/W.
For the top MOSFET, we now have deter-
mined the following requirements; BVdss =
30V, Rds(on) = 0.7m, Qgd = 2 nC and θja
< 96.6C/W.An SO-8 MOSFET that meets the
requirements is Vishay-Siliconix’s Si4394DY;
BVdss = 30V, Rds(on) = 9.75m @ Vgs = 4.5V,
Qgd = 2.nC and θja = 90 C/W.
The bottom MOSFET has the requirements of
BVdss = 30V and Rds(on) = 5.4m. Vishay-
Siliconix’s Si4320DYmeets the requirements;
BVdss = 30V, Rds(on) = 4m @ Vgs = 4.5V.
Power Good
Power Good (PWRGD) is an open drain
output that is pulled low when Vout is out-
side regulation. The PWRGD pin can be
connected to VCC with an external 0K
resistor. During startup, output regulates
whenSoftStart(SS)reaches0.8V(therefer-
ence voltage). PWRGD is enabled when SS
reaches .6V. PWRGD output can be used
as a “Power on Reset”. The simplest way to
adjust delay of the “Power on Reset” signal
with respect to Vout in regulation is with the
Soft Start Capacitor (Css) and is given by:
Css = (Iss x Tdelay)/0.8 where Iss is the Soft
Start charge current (0A nominal).
Under Voltage Lock Out (UVLO)
The SP638 has two separate UVLO com-
parators to monitor the bias (Vcc) and Input
(Vin)voltagesindependently.TheVccUVLO
is internally set to 4.25V. The Vin UVLO is
programmable through UVin pin. When
UVIN pin is greater than 2.5V the SP638
is permitted to start up pending the removal
of all other faults. A pair of internal resistors
is connected to UVIN as shown in figure 4.
Therefore without external biasing the Vin
start threshold is 9.5V.Asmall capacitor may
be required between UVIN and GND to filter
out noise. For applications with Vin of 5V or
3.3V, connect UVIN directly to Vin.
Figure 4- Internal and external bias of UVIN
SP613X
R4
R5
+
-
40K
50K
2.5V ON
2.2V OFF
GND
UVIN
VIN
APPLICATION INFORMATION
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SP6138ER1-L/TR | 功能描述:開(kāi)關(guān)變換器、穩(wěn)壓器與控制器 Synchronous Controller RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開(kāi)關(guān)頻率:1 MHz 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
| SP6139 | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Wide Input, 1.3MHz Synchronous PWM Controller |
| SP6139EU | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Wide Input, 1.3MHz Synchronous PWM Controller |
| SP6139EU/TR | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Wide Input, 1.3MHz Synchronous PWM Controller |
| SP6139EU-L | 功能描述:開(kāi)關(guān)變換器、穩(wěn)壓器與控制器 Wide Input, 1.3MHz Synchronous RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開(kāi)關(guān)頻率:1 MHz 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
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