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参数资料
| 型号： | TPS23756PWP |
| 厂商： | TEXAS INSTRUMENTS INC |
| 元件分类： | 稳压器 |
| 英文描述： | 1.1 A SWITCHING CONTROLLER, 278 kHz SWITCHING FREQ-MAX, PDSO20 |
| 封装： | GREEN, PLASTIC, HTSSOP-20 |
| 文件页数： | 20/41页 |
| 文件大小： | 1405K |
| 代理商： | TPS23756PWP |
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ADPTR_ON
PPDEN
PPD1
PPDEN
PPD
PPD2
V
18 V
1.55 V
R
=
= 32.26 k
V
1.55 V
5 A
I
3.01 k
R
÷
÷
-
÷
W
÷
÷
÷
- m
-
÷
÷
W
è
è
PPDEN
ADPTR_ON
PPDEN
PPD1
PPD
PPD2
V
= V
+ R
I
= 18.07 V
R
é
ù
-
ê
ú
÷
ê
ú
è
(
)
(
)
PPDEN
PPDH
ADPTR_OFF
PPDEN
PPDH
PPD1
PPD
PPD2
V
=
V
+ R
I
= 14.54 V
R
é
ù
-
ê
ú
-
-
÷
÷
ê
ú
è
(
)
2
DD
SS
RPPD
PPD1
PPD2
24 V
1.1
(V
V
)
P
=
= 19.6 mW
R
+ R
3.01 k
+ 32.4 k
-
W
FRS
SW
17250
R
(k ) =
=
= 69
f
(kHz)
250
W
TPS23754
TPS23754-1
TPS23756
www.ti.com
SLVS885D – OCTOBER 2008 – REVISED DECEMBER 2009
APD Pin Divider Network, RAPD1, RAPD2
The APD pin can be used to disable the TPS23754 internal hotswap MOSFET giving the adapter source priority
over the PoE source. An example calculation is provided, see literature number SLVA306A.
PPD Pin Divider Network, RPPD1, RPPD2
The PPD pin can be used to override the internal hotswap MOSFET UVLO (VUVLO_R and VUVLO_H) when using
low voltage adapters connected between VDD and VSS. The PPD pin has an internal 5 μA pulldown current
source. As an example, consider the choice of RPPD1 and RPPD2, for a 24 V adapter.
1. Select the startup voltage, VADPTR-ON approximately 75% of nominal for a 24 V adapter. Assuming that the
adapter output is 24 V ± 10%, this provides 15% margin below the minimum adapter operating voltage.
2. Choose VADPTR-ON = 24 V × 0.75 = 18 V
3. Choose RPPD2 = 3.01 k
4. Calculate RPPD1
(a)
(b) Choose RPPD1 = 32.4 k
5. Check PPD turn on and PPD turn off voltages
(a)
(b)
(c) Voltages look acceptable.
6. Check PPD resistor power consumption.
(a)
(b) Power is acceptable, but resistor values could be increased to reduce the power loss.
Setting Frequency (RFRS) and Synchronization
The converter switching frequency is set by connecting RFRS from the FRS pin to ARTN. The frequency may be
set as high as 1 MHz with some loss in programming accuracy as well as converter efficiency. Synchronization
at high duty cycles may become more difficult above 500 kHz due to the internal oscillator delays reducing the
available on-time. As an example:
1. Assume a desired switching frequency (fSW) of 250 kHz.
2. Compute RFRS:
(a)
(b) Select 69.8 k
.
The TPS23754 may be synchronized to an external clock to eliminate beat frequencies from a sampled system,
or to place emission spectrum away from an RF input frequency. Synchronization may be accomplished by
applying a short pulse (TSYNC) of magnitude VSYNC to FRS as shown in Figure 30. RFRS should be chosen so that
the maximum free-running frequency is just below the desired synchronization frequency. The synchronization
pulse terminates the potential on-time period, and the off-time period does not begin until the pulse terminates.
The pulse at the FRS pin should reach between 2.5 V and VB, with a minimum width of 22 ns (above 2.5 V) and
rise/fall times less than 10 ns. The FRS node should be protected from noise because it is high-impedance. An
RT on the order of 100 in the isolated example reduces noise sensitivity and jitter.
Copyright 2008–2009, Texas Instruments Incorporated
27
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相关代理商/技术参数 |
参数描述 |
|---|---|
| TPS23756PWPR | 功能描述:热插拔功率分布 Hi Pwr Eff PoE Inter face & DC/DC Cntrlr RoHS:否 制造商:Texas Instruments 产品:Controllers & Switches 电流限制: 电源电压-最大:7 V 电源电压-最小:- 0.3 V 工作温度范围: 功率耗散: 安装风格:SMD/SMT 封装 / 箱体:MSOP-8 封装:Tube |
| TPS23757EVM | 功能描述:电源管理IC开发工具 TPS23757 Eval Mod RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| TPS23757PW | 功能描述:热插拔功率分布 Hi Eff PoE Inter & DC/DC Controller RoHS:否 制造商:Texas Instruments 产品:Controllers & Switches 电流限制: 电源电压-最大:7 V 电源电压-最小:- 0.3 V 工作温度范围: 功率耗散: 安装风格:SMD/SMT 封装 / 箱体:MSOP-8 封装:Tube |
| TPS23757PWR | 功能描述:热插拔功率分布 Hi Eff PoE Interface & DC/DC Controller RoHS:否 制造商:Texas Instruments 产品:Controllers & Switches 电流限制: 电源电压-最大:7 V 电源电压-最小:- 0.3 V 工作温度范围: 功率耗散: 安装风格:SMD/SMT 封装 / 箱体:MSOP-8 封装:Tube |
| TPS2375D | 功能描述:热插拔功率分布 IEEE 802.3af PoE Pwr Device Cntrler RoHS:否 制造商:Texas Instruments 产品:Controllers & Switches 电流限制: 电源电压-最大:7 V 电源电压-最小:- 0.3 V 工作温度范围: 功率耗散: 安装风格:SMD/SMT 封装 / 箱体:MSOP-8 封装:Tube |
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