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參數(shù)資料
| 型號： | ISL6420AIRZ |
| 廠商： | INTERSIL CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Advanced Single Synchronous Buck Pulse-Width Modulation (PWM) Controller |
| 中文描述： | 0.05 A SWITCHING CONTROLLER, 1400 kHz SWITCHING FREQ-MAX, PQCC20 |
| 封裝： | 4 X 4 MM, GREEN, PLASTIC, MO-220, QFN-20 |
| 文件頁數(shù)： | 12/20頁 |
| 文件大?。?/td> | 560K |
| 代理商： | ISL6420AIRZ |
12
FN9169.1
October 13, 2005
Overcurrent Protection
The overcurrent function protects the converter from a
shorted output by using the upper MOSFET’s on-resistance,
r
DS(ON)
to monitor the current. This method enhances the
converter’s efficiency and reduces cost by eliminating a
current sensing resistor.
The overcurrent function cycles the soft-start function in a
hiccup mode with an ON time of 20ms and an OFF time of
128ms to provide fault protection. On detecting an
overcurrent condition, the IC waits for four soft-start cycles
before the output drivers are turned ON again, this process
is repeated till the overcurrent condition is removed. A
resistor connected to the drain of the upper FET and the
OCSET pin programs the overcurrent trip level. The PHASE
node voltage will be compared against the voltage on the
OCSET pin, while the upper FET is on. A current (100μA
typically) is pulled from the OCSET pin to establish the
OCSET voltage. If PHASE is lower than OCSET while the
upper FET is on then an overcurrent condition is detected for
that clock cycle. The upper gate pulse is immediately
terminated, and a counter is incremented. If an overcurrent
condition is detected for 8 consecutive clock cycles, and the
circuit is not in soft-start, the ISL6420A enters into the soft-
start hiccup mode. During hiccup, the external capacitor on
the ENSS pin is discharged. After the cap is discharged, it is
released and a soft-start cycle is initiated. During soft-start,
pulse termination current limiting is enabled, but the 8-cycle
hiccup counter is held in reset until soft-start is completed.
The overcurrent function will trip at a peak inductor current
(I
OC
) determined from Equation 1, where I
OCSET
is the
internal OCSET current source.
The OC trip point varies mainly due to the upper MOSFETs
r
DS(ON)
variations. To avoid overcurrent tripping in the
normal operating load range, find the R
OCSET
resistor from
the equation above with:
1. The maximum r
DS(ON)
at the highest junction
temperature.
2. Determine
where
I is the output inductor ripple current.
,
A small ceramic capacitor should be placed in parallel with
R
OCSET
to smooth the voltage across R
OCSET
in the
presence of switching noise on the input voltage.
Voltage Margining
The ISL6420A has a voltage margining mode that can be
used for system testing. The voltage margining percentage
is resistor selectable up to ±10%. The voltage margining
mode can be enabled by connecting a margining set resistor
from VMSET pin to ground and using the control pins
GPIO1/2 to toggle between positive and negative margining
(Refer to Table 2). With voltage margining enabled, the
VMSET resistor to ground will set a current, which is
switched to the FB pin. The current will be equal to 2.468V
divided by the value of the external resistor tied to the
VMSET pin.
The power supply output increases when GPIO2 is HIGH
and decreases when GPIO1 is HIGH. The amount that the
output voltage of the power supply changes with voltage
margining, will be equal to 2.468V times the ratio of the
external feedback resistor and the external resistor tied to
VMSET. Figure 10 shows the positive and negative
margining for a 3.3V output, using a 20.5k
feedback
resistor and using various VMSET resistor values.
I
OC
for I
OC
I
OUT MAX
)
I
(
)
2
+
>
I
VM
R
VMSET
-----------------------
=
(EQ. 2)
V
VM
2.468V
R
VMSET
-----------------------
=
(EQ. 3)
2.8
2.9
3.1
3.2
3.3
3.4
3.5
3.6
3.7
150
175
200
225
250
275
300
325
350
375
400
RVMSET (k
)
V
O
3.0
FIGURE 10. VOLTAGE MARGINING vs VMSET RESISTANCE
ISL6420A
相關(guān)PDF資料 |
PDF描述 |
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| ISL6420AIRZ-TK | Advanced Single Synchronous Buck Pulse-Width Modulation (PWM) Controller |
| ISL6420A | Advanced Single Synchronous Buck Pulse-Width Modulation (PWM) Controller(單片同步降壓脈寬調(diào)制控制器) |
| ISL6420AIAZ-TK | Circular Connector; No. of Contacts:22; Series:MS27473; Body Material:Aluminum; Connecting Termination:Crimp; Connector Shell Size:12; Circular Contact Gender:Socket; Circular Shell Style:Straight Plug; Insert Arrangement:12-35 RoHS Compliant: No |
| ISL6420IAZ-TK | PCB Relay; Contacts:SPDT; Contact Carry Current:500mA; Coil Voltage DC Max:9V; Relay Terminals:SMT Gullwing; Coil Resistance:405ohm; Contact Rating:10mA at 30VAC; Leaded Process Compatible:Yes; Peak Reflow Compatible (260 C):No RoHS Compliant: Yes |
| ISL6420IRZ-T | Advanced Single Synchronous Buck Pulse-Width Modulation (PWM) Controller |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ISL6420AIRZS2698 | 制造商:Intersil Corporation 功能描述:PB-FREE W/ANNEAL SYNC BUCK PWM CONT. WITH 4.5V-28V INPUT,20L - Rail/Tube |
| ISL6420AIRZ-TK | 功能描述:IC REG CTRLR BUCK PWM VM 20-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:75 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:1MHz 占空比:81% 電源電壓:4.3 V ~ 13.5 V 降壓:是 升壓:是 回掃:是 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:0°C ~ 70°C 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:管件 產(chǎn)品目錄頁面:1051 (CN2011-ZH PDF) 其它名稱:296-2543-5 |
| ISL6420AIRZ-TKR5264 | 功能描述:IC REG CTRLR BUCK PWM VM 20-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:275kHz 占空比:50% 電源電壓:18 V ~ 110 V 降壓:無 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:是 工作溫度:-40°C ~ 85°C 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:帶卷 (TR) |
| ISL6420AIRZ-TKS2698 | 制造商:Intersil Corporation 功能描述:PB-FREE W/ANNEAL SYNC BUCK PWM CONT. WITH 4.5V-28V INPUT,20L - Tape and Reel |
| ISL6420AIRZ-TKS2705 | 制造商:Intersil Corporation 功能描述:CISCO, ISL6420AIRZ-TK W/CONTAINER LABELING, SPECIAL CHANGE C - Rail/Tube |
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