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參數(shù)資料
| 型號： | TPS61120 |
| 廠商： | Texas Instruments, Inc. |
| 英文描述： | SYNCHRONOUS BOOST CONVERTER WITH 1.1A SWITCH AND INTEGRATED LDO |
| 中文描述： | 同步升壓轉(zhuǎn)換器與1.1A的開關(guān)和集成穩(wěn)壓器 |
| 文件頁數(shù)： | 15/25頁 |
| 文件大?。?/td> | 462K |
| 代理商： | TPS61120 |
www.ti.com
R5
R4
VO
VFB
–1
180 k
VO
500 mV–1
(3)
Programming the LBI/LBO Threshold Voltage
R1
R2
VBAT
threshold
VLBI
1
390 k
VBAT
500 mV
1
(4)
Inductor Selection
IL
IOUT
VOUT
VBAT
0.8
(5)
L
VBAT
VOUT–VBAT
VOUT
IL
(6)
TPS61120
TPS61122, TPS61121
SLVS427C–JUNE 2002–REVISED APRIL 2004
LDO
Programming the output voltage at the LDO follows almost the same rules as in the dc/dc converter section. The
maximum programmable output voltage at the LDO is 5.5 V. Since reference and internal feedback circuitry are
similar, as they are at the boost converter section, R4 also should be in the 200-k
range. The calculation of the
value of R5 can be done using the following Equation 3:
If as an example, an output voltage of 1.5 V is needed, a 360 k
-resistor should be chosen for R5.
The current through the resistive divider should be about 100 times greater than the current into the LBI pin. The
typical current into the LBI pin is 0.01 μA, and the voltage across R2 is equal to the LBI voltage threshold that is
generated on-chip, which has a value of 500 mV. The recommended value for R2is therefore in the range of 500
k
. From that, the value of resistor R1, depending on the desired minimum battery voltage V
BAT,
can be
calculated using Equation 4.
The output of the low battery supervisor is a simple open-drain output that goes active low if the dedicated
battery voltage drops below the programmed threshold voltage on LBI. The output requires a pullup resistor with
a recommended value of 1 M
. The maximum voltage which is used to pull up the LBO outputs should not
exceed the output voltage of the dc/dc converter. If not used, the LBO pin can be left floating or tied to GND.
A boost converter normally requires two main passive components for storing energy during the conversion. A
boost inductor and a storage capacitor at the output are required. To select the boost inductor, it is
recommended to keep the possible peak inductor current below the current limit threshold of the power switch in
the chosen configuration. For example, the current limit threshold of the TPS6112x's switch is 1600 mA at an
output voltage of 3.3 V. The highest peak current through the inductor and the switch depends on the output
load, the input (V
BAT
), and the output voltage (V
OUT
). Estimation of the maximum average inductor current can be
done using Equation 5:
For example, for an output current of 250 mA at 3.3 V, at least 575 mA of current flows through the inductor at a
minimum input voltage of 1.8 V.
The second parameter for choosing the inductor is the desired current ripple in the inductor. Normally, it is
advisable to work with a ripple in the range of 20% of the average inductor current. A smaller ripple reduces the
magnetic hysteresis losses in the inductor, as well as output voltage ripple and EMI. But in the same way,
regulation time at load changes rises. In addition, a larger inductor increases the total system costs. With those
parameters, it is possible to calculate the value for the inductor by using Equation 6:
Parameter
f
is the switching frequency and
I
L
is the ripple current in the inductor, i.e., 20%
×
I
L
. In this example,
the desired inductor value is in the range of 14 μH. In typical applications a 10 μH inductor is recommended. The
minimum possible inductor value is 4.7 μH. With the calculated inductance value and current, it is possible to
choose a suitable inductor. Care has to be taken that load transients and losses in the circuit can lead to higher
currents as estimated in Equation 5. Also, the losses in the inductor caused by magnetic hysteresis losses and
copper losses are a major parameter for total circuit efficiency.
The following inductor series from different suppliers have been used with the TPS6112x converters:
15
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| TPS61120EVM-205 | 功能描述:電源管理IC開發(fā)工具 TPS61120-205 Eval Mod RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| TPS61120PW | 功能描述:直流/直流開關(guān)調(diào)節(jié)器 Adj Hi-Eff Boost Cnvrtr w/200mA LDO RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| TPS61120PWG4 | 功能描述:直流/直流開關(guān)調(diào)節(jié)器 Adj Hi-Eff Boost Cnvrtr w/200mA LDO RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| TPS61120PWR | 功能描述:直流/直流開關(guān)調(diào)節(jié)器 Adj Hi-Eff Boost Cnvrtr w/200mA LDO RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| TPS61120PWRG4 | 功能描述:直流/直流開關(guān)調(diào)節(jié)器 Adj Hi-Eff Boost Cnvrtr w/200mA LDO RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
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