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参数资料
| 型号： | TPS75003MRHLREP |
| 厂商： | TEXAS INSTRUMENTS INC |
| 元件分类： | 电源管理 |
| 英文描述： | 3-CHANNEL POWER SUPPLY SUPPORT CKT, PQCC20 |
| 封装： | 4.50 X 3.50 MM, 0.90 MM HEIGHT, PLASTIC, QFN-20 |
| 文件页数： | 6/29页 |
| 文件大小： | 1210K |
| 代理商： | TPS75003MRHLREP |
第1页第2页第3页第4页第5页当前第6页第7页第8页第9页第10页第11页第12页第13页第14页第15页第16页第17页第18页第19页第20页第21页第22页第23页第24页第25页第26页第27页第28页第29页
IS1,2
1,2
V
I
=
LIMIT
R
(
)
OUT
RMS
OUT
IN
2
DISS
RMS
V
I
= I
D = I
V
P
=
I
R
SGLS311A
– DECEMBER 2006 – REVISED MARCH 2011
Current Limit (Buck Controllers)
An external resistor (R1 or R2) is used to set the current limit for the external PMOS transistor (Q1 or Q2). These
resistors are connected between IN1 and IS1 (or IN2 and IS2) to provide a reference voltage across these pins
that is proportional to the current flowing through the PMOS transistor. This reference voltage is compared to an
internal reference to determine if an over-current condition exists. When current limit is exceeded, the external
PMOS is turned off for the minimum off-time. Current limit detection is disabled for 10 ns any time the PMOS is
turned on to avoid triggering on switching noise. In 100% duty cycle mode, current limit is always enabled.
Current limit is calculated using the VIS1 or VIS2 specification in the Electrical Characteristics section, shown in
(1)
The current limit resistor must be appropriately rated for the dissipated power determined by its RMS current
calculated by Equation 2.
(2)
For low-cost applications the IS1,2 pin can be connected to the drain of the PMOS, using RDS,ON instead of R1 or
R2 to set current limit. Variations in the PMOS RDS,ON must be taken into account to ensure that current limit will
protect external components such as the inductor, the diode, and the switch itself from damage as a result of
overcurrent.
Short-Circuit Protection (Buck Controllers)
In an overload condition, the current rating of the external components (PMOS, diode, and inductor) can be
exceeded. To help guard against this, the TPS75003 increases its minimum off-time when the voltage at the
feedback pin is lower than the reference voltage. When the output is shorted (VFB is zero), minimum off-time is
increased to approximately 4
μs. The increase in off-time is proportional to the difference between the voltage at
the feedback pin and the internal reference.
Soft-Start (Buck Controllers)
The buck controllers each have independent soft-start capability to limit inrush during start-up and to meet timing
requirements of the Xilinx Spartan-3 FPGA. Limiting inrush current by using soft-start, or by staggering the
turn-on of power rails, also guards against voltage drops at the input source due to its output impedance. See the
soft-start circuitry shown in Figure 23 and the soft-start timing diagram shown in Figure 24. BUCK 1 will be
discussed in this section; it is identical to BUCK2. Note that pins SS1 and SS2 are high-impedance and cannot
be probed using a typical oscilloscope setup. When input voltage is applied at IN1 and EN1 is driven low, any
charge on the SS pin is discharged by an on-chip pulldown transistor. When EN1 is driven high, an on-chip
current source starts charging the external soft-start capacitor CSS1. The voltage on the capacitor is compared to
the voltage across the current sense resistor R1 to determine if an over-current condition exists. If the voltage
drop across the sense resistor goes above the reference voltage, then the external PMOS is shut off for the
minimum off-time. This implementation provides a cycle-by-cycle current limit and allows the user to program the
soft-start time over a wide range for most applications. For detailed information on choosing CSS1 and CSS2, see
the section, Selecting the Soft-Start Cap.
14
Copyright
2006–2011, Texas Instruments Incorporated
Product Folder Link(s): TPS75003-EP
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| TPS75003QRHLREP | 功能描述:IC PWR MGMT TRIPLE-SUPPLY 20-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 电源管理 - 专用 系列:- 应用说明:Ultrasound Imaging Systems Application Note 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:37 系列:- 应用:医疗用超声波成像，声纳 电流 - 电源:- 电源电压:2.37 V ~ 6 V 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:56-WFQFN 裸露焊盘 供应商设备封装:56-TQFN-EP（8x8） 包装:管件 |
| TPS75003RHLR | 功能描述:PMIC 解决方案 Integ 3-Supply Power Mngmnt IC RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
| TPS75003RHLR | 制造商:Texas Instruments 功能描述:LEADED PROCESS COMPATIBLE ((NW)) 制造商:Texas Instruments 功能描述:IC, POWER MANAGEMENT, QFN-20 |
| TPS75003RHLRG4 | 功能描述:PMIC 解决方案 Integ 3-Supply Power Mngmnt IC RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
| TPS75003RHLT | 功能描述:PMIC 解决方案 Integ 3-Supply Power Mngmnt IC RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
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