參數資料
型號: L5988D
廠商: STMICROELECTRONICS
元件分類: 穩(wěn)壓器
英文描述: 5.6 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO16
封裝: LEAD FREE, HTSSOP-16
文件頁數: 10/52頁
文件大小: 1858K
代理商: L5988D
Functional description
L5988D
18/52
Doc ID 15324 Rev 3
5.3
External voltage reference
An external 1.8 V regulated voltage is provided. This reference is useful to set the voltage at
the multifunction pin (see 5.1) or to source current to ILIM-ADJ and FSW pins (see and
5.5.2). The typical current capability is 4 mA.
5.4
Soft-start
When VCC is above the selected UVLO threshold the start-up phase takes place. At start-
up, a voltage ramp is generated charging the external capacitor CSS with an internal current
generator. The device is in inhibit mode as long as SS/INH pin is below the INH threshold.
The L5988D implements the soft-start phase by clamping the output of the error amplifier
and, being based on a voltage mode control, the duty cycle. In fact the comparison between
the output of the error amplifier and the internal saw tooth waveform generates the duty
cycle needed to keep the output voltage in regulation.
Two different current sources charge the external capacitor depending on the pin voltage in
order to reduce the power consumption in INH mode.
The equation for the soft-start time is:
Considering ISS2/ISS1 = 22/5 = 4.4, the proper soft-start capacitor is simply calculated as
follows:
During the soft-start phase (VSS < 2.9 V):
the sink capability is always disabled (independently from the multifunction pin settings)
to be compatible with pre-biased output voltage
in case the overcurrent limit is detected, a constant current protection is provided in
order to deliver extra current for charging the output capacitor (see 5.5.2 for description
of current protection management).
I
SS
I
SS1
5
=
μA
0
V
SS/INH
1
<<
I
SS2
2
=
2
μA
1
V
SS/INH
2.9
<<
=
T
SS
T
1
Δ
T
2
Δ
+
C
SS
I
SS1
-----------
10
()
×
C
SS
I
SS2
-----------
2.9
1
()
×
+
==
CnF
()
Tss mS
() 3.5
×
=
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相關代理商/技術參數
參數描述
L5988DTR 功能描述:直流/直流開關調節(jié)器 4A Step Down Reg 2.9V to 18V 200ns RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數量: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5
L5989D 功能描述:直流/直流開關調節(jié)器 4A cont 5A pulsed step-down sw RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數量: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5
L5989DTR 功能描述:直流/直流開關調節(jié)器 4A cont 5A pulsed step-down sw RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數量: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5
L5991 功能描述:電流型 PWM 控制器 Prog Current Mode RoHS:否 制造商:Texas Instruments 開關頻率:27 KHz 上升時間: 下降時間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數量:1 最大工作溫度:+ 105 C 安裝風格:SMD/SMT 封裝 / 箱體:TSSOP-14
L5991_01 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:PRIMARY CONTROLLER WITH STANDBY