參數(shù)資料
型號： L7981TR
廠商： STMICROELECTRONICS
元件分類： 穩(wěn)壓器
英文描述： SWITCHING REGULATOR, DSO8
封裝： 3 X 3 MM, 1.08 MM HEIGHT, ROHS COMPLIANT, VFQFP-8
文件頁數(shù)： 11/44頁
文件大?。?/td> 1315K
代理商： L7981TR
L7981
Application informations
Doc ID 15182 Rev 3
19/44
6.4
Compensation network
The compensation network has to assure stability and good dynamic performance. The loop
of the L7981 is based on the voltage mode control. The error amplifier is a voltage
operational amplifier with high bandwidth. So selecting the compensation network the E/A
will be considered as ideal, that is, its bandwidth is much larger than the system one.
The transfer functions of PWM modulator and the output LC filter are studied (see Figure
10.). The transfer function of the PWM modulator, from the error amplifier output (COMP
pin) to the OUT pin, results:
Equation 13
where VS is the sawtooth amplitude. As seen in Chapter 5.1, the voltage feed forward
generates a sawtooth amplitude directly proportional to the input voltage, that is:
Equation 14
In this way the PWM modulator gain results constant and equals to:
Equation 15
The synchronization of the device with an external clock provided trough SYNCH pin can
modifies the PWM modulator gain (see Chapter 5.1 to understand how this gain changes
and how to keep it constant in spite of the external synchronization).
Figure 9.
The error amplifier, the PWM modulation and the LC output filter
The transfer function on the LC filter is given by:
G
PW0
V
IN
V
s
---------
=
V
S
KV
IN
=
G
PW0
V
IN
V
s
---------
1
K
----
13
==
=
FB
COMP
V
REF
E/A
PWM
V
S
OUT
V
CC
C
OUT
ESR
L
G
PW0
G
LC
FB
COMP
V
REF
E/A
PWM
V
S
OUT
V
CC
C
OUT
ESR
L
G
PW0
G
LC
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
L7983 制造商:Leviton Manufacturing Co 功能描述:
L7985 功能描述:線性穩(wěn)壓器 - 標(biāo)準 2A Step Down REG 4.5V to 38V 250 KHz RoHS:否 制造商:STMicroelectronics 輸出類型: 極性: 輸出電壓:1.8 V 輸出電流:150 mA 負載調(diào)節(jié): 最大輸入電壓:5.5 V 線路調(diào)整率: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOT-323-5L
L7985A 功能描述:直流/直流開關(guān)調(diào)節(jié)器 2A DC 4.5V to 38V 250 KHz Step-Down 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
L7985ATR 功能描述:線性穩(wěn)壓器 - 標(biāo)準 2A Step-Down REG 2A DC 4.5 to 38V RoHS:否 制造商:STMicroelectronics 輸出類型: 極性: 輸出電壓:1.8 V 輸出電流:150 mA 負載調(diào)節(jié): 最大輸入電壓:5.5 V 線路調(diào)整率: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOT-323-5L
L7985TR 功能描述:線性穩(wěn)壓器 - 標(biāo)準 2A Step-Down Reg 4.5V to 38V 250 KHz RoHS:否 制造商:STMicroelectronics 輸出類型: 極性: 輸出電壓:1.8 V 輸出電流:150 mA 負載調(diào)節(jié): 最大輸入電壓:5.5 V 線路調(diào)整率: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOT-323-5L
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