參數(shù)資料
型號(hào): L5980TR
廠商: STMICROELECTRONICS
元件分類: 穩(wěn)壓器
英文描述: 1.6 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO8
封裝: 3 X 3 MM, 1.08 MM HEIGHT, ROHS COMPLIANT, VFQFPN-8
文件頁數(shù): 3/42頁
文件大?。?/td> 1188K
代理商: L5980TR
L5980
Functional description
Doc ID 13003 Rev 6
11/42
4.2
Soft-start
The soft-start is essential to assure correct and safe start up of the step-down converter. It
avoids inrush current surge and makes the output voltage increases monothonically.
The soft-start is performed by a staircase ramp on the non-inverting input (VREF) of the error
amplifier. So the output voltage slew rate is:
Equation 1
where SRVREF is the slew rate of the non-inverting input while R1 and R2 the resistor divider
to regulate the output voltage (see Figure 7). The soft-start stair case consists of 64 steps of
9.5 mV each one, from 0 V to 0.6 V. The time base of one step is of 32 clock cycles. So the
soft-start time and then the output voltage slew rate depend on the switching frequency.
Figure 7.
Soft-start scheme
Soft-start time results:
Equation 2
For example with a switching frequency of 250 kHz the SSTIME is 8 ms.
SR
OUT
SR
VREF
1
R1
R2
--------
+
=
SS
TIME
32 64
Fsw
-----------------
=
相關(guān)PDF資料
PDF描述
L5983 1.5 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO8
L5983TR 1.5 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO8
L5986A 3.9 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO8
L5986ATR 3.9 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO8
L5986TR 3.9 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO8
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