参数资料
型号: L6730
厂商: STMICROELECTRONICS
元件分类: 稳压器
英文描述: 20 A SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO20
封装: HTSSOP-20
文件页数: 28/52页
文件大小: 1569K
代理商: L6730
Application details
L6730 - L6730B
34/52
Doc ID 11938 Rev 3
6.2
Output capacitors
The output capacitors are basic components for the fast transient response of the power
supply. They depend on the output voltage ripple requirements, as well as any output
voltage deviation requirement during a load transient. During a load transient, the output
capacitors supply the current to the load or absorb the current stored into the inductor until
the converter reacts. In fact, even if the controller recognizes immediately the load transient
and sets the duty cycle at 100% or 0%, the current slope is limited by the inductor value. The
output voltage has a first drop due to the current variation inside the capacitor (neglecting
the effect of the ESL):
Moreover, there is an additional drop due to the effective capacitor discharge or charge that
is given by the following formulas:
Formula (8) is valid in case of positive load transient while the formula (9) is valid in case of
negative load transient. DMAX is the maximum duty cycle value that in the L6730/B is 100%.
For a given inductor value, minimum input voltage, output voltage and maximum load
transient, a maximum ESR, and a minimum COUT value can be set. The ESR and COUT
values also affect the static output voltage ripple. In the worst case the output voltage ripple
can be calculated with the following formula:
Usually the voltage drop due to the ESR is the biggest one while the drop due to the
capacitor discharge is almost negligible.
6.3
Input capacitors
The input capacitors have to sustain the RMS current flowing through them, that is:
Where D is the duty cycle. The equation reaches its maximum value, IOUT/2 with D = 0.5.
The losses in worst case are:
ESR
Iout
Vout
ESR
Δ
=
Δ
(7)
)
max
min
,
(
2
Vout
D
Vin
Cout
L
Iout
Vout
COUT
Δ
=
Δ
(8)
Vout
Cout
L
Iout
Vout
COUT
Δ
=
Δ
2
(9)
)
8
1
(
Fsw
Cout
ESR
I
Vout
L
+
Δ
=
Δ
(10)
)
1
(
D
Iout
Irms
=
(11)
2
)
5
.
0
(
Iout
ESR
P
=
(12)
相关PDF资料
PDF描述
L6730B 20 A SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO20
L6730TR 20 A SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO20
L6732CTR 20 A SWITCHING CONTROLLER, 500 kHz SWITCHING FREQ-MAX, PDSO16
L6732 SWITCHING CONTROLLER, 500 kHz SWITCHING FREQ-MAX, PDSO16
L6732TR SWITCHING CONTROLLER, 500 kHz SWITCHING FREQ-MAX, PDSO16
相关代理商/技术参数
参数描述
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L6730CQ 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:Adjustable step-down controller with synchronous rectification