參數(shù)資料
型號(hào): AN8049
廠商: Panasonic Corporation
元件分類: DC/DC變換器
英文描述: 1.8-volt 3-channel step-up, step-down, and polarity inverting DC-DC converter control IC
中文描述: 1.8伏3通道升壓,降壓,和極性倒轉(zhuǎn)DC - DC轉(zhuǎn)換器控制IC
文件頁數(shù): 18/23頁
文件大?。?/td> 170K
代理商: AN8049
AN8049FHN
Voltage Regulators
18
I
Application Notes (continued)
[5] Time constant setup for the timer latch short-circuit protection circuit
Figure 6 shows the structure of the timer latch short-circuit protection circuit. The short-circuit protection
comparator continuously compares a 0.9 V reference voltage with the FB1, FB2, and FB3 error amplifier outputs.
When the DC-DC converter output load conditions are stable, the short-circuit protection comparator holds its
average value since there are no fluctuations in the error amplifier outputs. At this time, the output transistor Q1 will
be in the conducting state, and the S.C.P. pin will be held at 0 V.
If the output load conditions change rapidly and a high-level signal (0.9 V or higher) is input to the short-circuit
protection comparator from the error amplifier output, the short-circuit protection comparator will output a low level
and the output transistor Q1 will shut off. Then, the capacitor C
SCP
connected to the S.C.P. pin will start to charge.
When the external capacitor C
SCP
is charged to about 1.26 V by the constant current of about 1.1 mA, the latch circuit
will latch and the dead-time will be set to 100% with the output held fixed at the low level. Once the latch circuit has
latched, the S.C.P. pin capacitor will be discharged to about 0 V, but the latch circuit will not reset unless either power
is turned off or the power supply is restarted using on/off control.
1.26 V
=
I
CHG
×
t
PE
C
SCP
t
PE
(s)
=
1.15
×
C
SCP
(
μ
F)
At power supply startup, the output appears to be
in the shorted state, and the IC starts to charge the
S.C.P. pin capacitor. Therefore, users must select an
external capacitor that allows the DC-DC converter
output voltage to rise before the latch circuit in the
later stage latches. In particular, care is required if the
soft start function is used, since that function makes
the startup time longer.
Figure 5. S.C.P. pin charging waveform
Figure 6. Short-circuit protection circuit
Short-circuit detection time t
PE
t (s)
0
1.26
V
SCP
(V)
FB2
FB3
FB1
0.9 V
S.C.P. comp.
S.C.P.
High level detection comparator
1.26 V
V
REF
V
CC
Q1
On/off control
1.1
μ
A
U.V.L.O.
R
S
Q
Latch
Output shutoff
22
18
20
2
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AN8049FHN 制造商:PANASONIC 制造商全稱:Panasonic Semiconductor 功能描述:1.8-volt 3-channel step-up, step-down, and polarity inverting DC-DC converter control IC
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AN8049SH 制造商:PANASONIC 制造商全稱:Panasonic Semiconductor 功能描述:1.8-volt 3-channel step-up, step-down, and polarity inverting DC-DC converter control IC
AN8049SH-E1 功能描述:IC REG BUCK BST INV 40MA 24SSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 產(chǎn)品培訓(xùn)模塊:High Efficiency Current Mode Switching Regulators CMOS LDO Regulators 特色產(chǎn)品:BD91x Series Step-Down Regulators 標(biāo)準(zhǔn)包裝:2,500 系列:- 類型:降壓(降壓) 輸出類型:兩者兼有 輸出數(shù):2 輸出電壓:3.3V,0.8 V ~ 2.5 V 輸入電壓:4.5 V ~ 5.5 V PWM 型:電流模式 頻率 - 開關(guān):1MHz 電流 - 輸出:1.5A 同步整流器:是 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:20-VFQFN 裸露焊盤 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:VQFN020V4040 產(chǎn)品目錄頁面:1373 (CN2011-ZH PDF) 其它名稱:BD9152MUV-E2TR