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參數(shù)資料
| 型號(hào)： | ISL6526AIBZ |
| 廠商： | INTERSIL CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Single Synchronous Buck Pulse-Width Modulation (PWM) Controller |
| 中文描述： | 2 A SWITCHING CONTROLLER, 640 kHz SWITCHING FREQ-MAX, PDSO14 |
| 封裝： | ROHS COMPLIANT, PLASTIC, MS-012-AB, SOIC-14 |
| 文件頁數(shù)： | 12/15頁 |
| 文件大小： | 340K |
| 代理商： | ISL6526AIBZ |
12
FN9055.8
March 20, 2007
The maximum RMS current required by the regulator may be
closely approximated through the following equation:
For a through hole design, several electrolytic capacitors may
be needed. For surface mount designs, solid tantalum
capacitors can be used, but caution must be exercised with
regard to the capacitor surge current rating. These capacitors
must be capable of handling the surge-current at power-up.
Some capacitor series available from reputable manufacturers
are surge current tested.
MOSFET Selection/Considerations
The ISL6526, ISL6526A require two N-Channel power
MOSFETs. These should be selected based upon r
DS(ON)
,
gate supply requirements, and thermal management
requirements.
In high-current applications, the MOSFET power dissipation,
package selection and heatsink are the dominant design
factors. The power dissipation includes two loss components;
conduction loss and switching loss. The conduction losses are
the largest component of power dissipation for both the upper
and the lower MOSFETs. These losses are distributed between
the two MOSFETs according to duty factor. The switching
losses seen when sourcing current will be different from the
switching losses seen when sinking current. When sourcing
current, the upper MOSFET realizes most of the switching
losses. The lower switch realizes most of the switching losses
when the converter is sinking current (see equations on next
page). These equations assume linear voltage-current
transitions and do not adequately model power loss due the
reverse-recovery of the upper and lower MOSFET’s body
diode. The gate-charge losses are dissipated by the ISL6526,
ISL6526A and don't heat the MOSFETs. However, large gate-
charge increases the switching interval, t
SW
which increases
the
MOSFET
switching losses. Ensure that both MOSFETs are
within their maximum junction temperature at high ambient
temperature by calculating the temperature rise according to
package thermal-resistance specifications. A separate heatsink
may be necessary depending upon MOSFET power, package
type, ambient temperature and air flow.
Given the reduced available gate bias voltage (5V), logic-
level or sub-logic-level transistors should be used for both
N-MOSFETs. Caution should be exercised with devices
exhibiting very low V
GS(ON)
characteristics. The shoot-
through protection present aboard the ISL6526, ISL6526A
may be circumvented by these MOSFETs if they have large
parasitic impedances and/or capacitances that would inhibit
the gate of the MOSFET from being discharged below its
threshold level before the complementary MOSFET is turned
on.
Bootstrap Component Selection
External bootstrap components, a diode and capacitor, are
required to provide sufficient gate enhancement to the upper
MOSFET. The internal MOSFET gate driver is supplied by
the external bootstrap circuitry as shown in Figure 7. The
boot capacitor, C
BOOT
, develops a floating supply voltage
referenced to the PHASE pin. This supply is refreshed each
cycle, when D
BOOT
conducts, to a voltage of CPVOUT less
the boot diode drop, V
D
, plus the voltage rise across
Q
LOWER
.
Just after the PWM switching cycle begins and the charge
transfer from the bootstrap capacitor to the gate capacitance
is complete, the voltage on the bootstrap capacitor is at its
lowest point during the switching cycle. The charge lost on
the bootstrap capacitor will be equal to the charge
transferred to the equivalent gate-source capacitance of the
upper MOSFET as shown:
where Q
GATE
is the maximum total gate charge of the upper
MOSFET, C
BOOT
is the bootstrap capacitance, V
BOOT1
is
the bootstrap voltage immediately before turn-on, and
V
BOOT2
is the bootstrap voltage immediately after turn-on.
The bootstrap capacitor begins its refresh cycle when the gate
drive begins to turn-off the upper MOSFET. A refresh cycle
I
RMSMAX
V
IN
-------------
I
OUTMAX
2
1
12
------
V
----------------------------
V
s
–
V
IN
-------------
×
2
×
+
×
=
(EQ. 8)
P
LOWER
= Io
2
x r
DS(ON)
x (1 - D)
Where: D is the duty cycle = V
OUT
/ V
IN
,
t
SW
is the combined switch ON and OFF time, and
f
s
is the switching frequency.
Losses while Sourcing current
Io
2
=
Losses while Sinking current
P
UPPER
= Io
2
x r
DS(ON)
x D
P
LOWER
Io
2
r
DS ON
(
)
×
1
D
–
(
)
×
1
2
--
Io
V
IN
×
t
SW
f
s
×
×
+
=
P
UPPER
r
DS ON
)
×
D
×
1
2
--
Io
V
IN
×
t
SW
f
s
×
×
+
(EQ. 9)
ISL6526,
ISL6526A
GND
LGATE
UGATE
PHASE
BOOT
V
IN
NOTE:
V
G-S
= V
CC
-V
D
NOTE:
V
G-S
= V
CC
C
BOOT
D
BOOT
Q
UPPER
Q
LOWER
+
FIGURE 7. UPPER GATE DRIVE BOOTSTRAP
+
V
D
-
CPVOUT
Q
GATE
C
BOOT
V
BOOT1
V
BOOT2
–
(
)
×
=
(EQ. 10)
ISL6526, ISL6526A
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ISL6526AIR | 功能描述:電壓模式 PWM 控制器 Single Synch Buck RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
| ISL6526AIR-T | 功能描述:IC REG CTRLR BUCK PWM VM 16-QFN RoHS:否 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:4,000 系列:- PWM 型:電壓模式 輸出數(shù):1 頻率 - 最大:1.5MHz 占空比:66.7% 電源電壓:4.75 V ~ 5.25 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 85°C 封裝/外殼:40-VFQFN 裸露焊盤 包裝:帶卷 (TR) |
| ISL6526AIRZ | 功能描述:電壓模式 PWM 控制器 600KHZ SNG PWM W/CHA RGE PUMP 16LD 5X5 RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
| ISL6526AIRZ-T | 功能描述:電壓模式 PWM 控制器 600KHZ SINGLE PWM W/CHRG PUMP 16LD 5X5 RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
| ISL6526AIRZ-TK | 功能描述:IC REG CTRLR BUCK PWM VM 16-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) |
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