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參數(shù)資料
| 型號(hào)： | ISL6569CBZ |
| 廠商： | INTERSIL CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Multi-Phase PWM Controller |
| 中文描述： | SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO24 |
| 封裝： | LEAD FREE, PLASTIC, MS-013-AD, SOIC-24 |
| 文件頁數(shù)： | 16/22頁 |
| 文件大?。?/td> | 497K |
| 代理商： | ISL6569CBZ |
16
FN9085.7
December 29, 2004
MOSFETs
The choice of MOSFETs depends on the current each
MOSFET will be required to conduct; the switching frequency;
the capability of the MOSFETs to dissipate heat; and the
availability and nature of heat sinking and air flow.
LOWER MOSFET POWER CALCULATION
The calculation for heat dissipated in the lower MOSFET is
simple, since virtually all of the heat loss in the lower
MOSFET is due to current conducted through the channel
resistance (r
DS(ON)
). In Equation 13, I
M
is the maximum
continuous output current; I
PP
is the peak-to-peak inductor
current (see Equation 1); d is the duty cycle (V
OUT
/V
IN
); N is
the number of active channels; and L is the per-channel
inductance.
An additional term can be added to the lower-MOSFET loss
equation to account for additional loss accrued during the
dead time when inductor current is flowing through the
lower-MOSFET body diode. This term is dependent on the
diode forward voltage at I
M
, V
D(ON)
; the switching frequency,
f
S
; and the length of dead times, t
d1
and t
d2
, at the
beginning and the end of the lower-MOSFET conduction
interval respectively.
Thus the total maximum power dissipated in each lower
MOSFET is approximated by the summation of P
L
and P
D
.
UPPER MOSFET POWER CALCULATION
In addition to r
DS(ON)
losses, a large portion of the upper-
MOSFET losses are due to currents conducted across the
input voltage (V
IN
) during switching. Since a substantially
higher portion of the upper-MOSFET losses are dependent
on switching frequency, the power calculation is more
complex. Upper MOSFET losses can be divided into
separate components involving the upper-MOSFET
switching times; the lower-MOSFET body-diode reverse-
recovery charge, Q
rr
; and the upper MOSFET r
DS(ON)
conduction loss.
When the upper MOSFET turns off, the lower MOSFET does
not conduct any portion of the inductor current until the
voltage at the phase node falls below ground. Once the
lower MOSFET begins conducting, the current in the upper
MOSFET falls to zero as the current in the lower MOSFET
ramps up to assume the full inductor current. In Equation 15,
the required time for this commutation is t
1
and the
approximated associated power loss is P
UP,1
.
The upper MOSFET begins to conduct and this transition
occurs over a time t
2
. In Equation 16, the approximate power
loss is P
UP,2
.
A third component involves the lower MOSFET’s reverse-
recovery charge, Q
rr
. Since the inductor current has fully
commutated to the upper MOSFET before the lower-
MOSFET’s body diode can draw all of Q
rr
, it is conducted
through the upper MOSFET across VIN. The power
dissipated as a result is P
UP,3
and is approximately
Finally, the resistive part of the upper MOSFET’s dissipation
is given in Equation 18 as P
UP,4
.
In this case, of course, r
DS(ON)
is the on resistance of the
upper MOSFET.
The total power dissipated by the upper MOSFET at full load
can now be approximated as the summation of the results
from Equations 15, 16, 17 and 18. Since the power
equations depend on MOSFET parameters, choosing the
correct MOSFETs can be an iterative process that involves
repetitively solving the loss equations for different MOSFETs
and different switching frequencies until converging upon the
best solution.
Current Sensing
The ISEN pins are denoted ISEN1 and ISEN2. The resistors
connected between these pins and their respective phase
nodes determine the gain in the load-line regulation loop and
the channel-current balance loop. Select the values for these
resistors based on the room temperature r
DS(ON)
of the
lower MOSFETs; the full-load operating current, I
FL
;
according to Equation 19 (see also Figure 4).
In certain circumstances, it may be necessary to adjust the
value of one or both of the ISEN resistors. This can arise
when the components of one channel are inhibited from
dissipating their heat so that the affected channel runs hotter
than desired (see the section entitled
Channel-Current
P
L
r
DS ON
(
)
I
M
2
-----
2
1
d
–
(
)
I
,
-------------12
2
1
d
–
(
)
+
=
(EQ. 13)
P
D
V
D ON
)
f
S
I
M
2
-----
I
---2
+
t
d1
I
M
2
-----
I
---2
–
t
d2
+
=
(EQ. 14)
P
UP 1
V
IN
I
M
2
-----
I
---2
+
t
1
2
----
f
S
≈
(EQ. 15)
P
UP 2
,
V
IN
I
M
2
-----
I
---2
–
t
2
2
----
f
S
≈
(EQ. 16)
P
UP 3
V
IN
Q
rr
f
S
≈
(EQ. 17)
P
UP 4
r
DS ON
)
I
M
2
-----
2
d
I
2
12
+
=
(EQ. 18)
R
ISEN
r
50 10
6
)
–
-----------------------
I
-2
=
(EQ. 19)
ISL6569
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| ISL6569CBZ-T | 功能描述:IC REG CTRLR DIVIDER PWM 24-SOIC 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) |
| ISL6569CR | 功能描述:IC REG CTRLR DIVIDER PWM 32-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:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:100% 電源電壓:8.2 V ~ 30 V 降壓:無 升壓:無 回掃:是 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:是 工作溫度:0°C ~ 70°C 封裝/外殼:8-DIP（0.300"，7.62mm） 包裝:管件 產(chǎn)品目錄頁面:1316 (CN2011-ZH PDF) |
| ISL6569CR-T | 功能描述:IC REG CTRLR DIVIDER PWM 32-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:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:100% 電源電壓:8.2 V ~ 30 V 降壓:無 升壓:無 回掃:是 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:是 工作溫度:0°C ~ 70°C 封裝/外殼:8-DIP（0.300"，7.62mm） 包裝:管件 產(chǎn)品目錄頁面:1316 (CN2011-ZH PDF) |
| ISL6569CRZ | 功能描述:IC REG CTRLR DIVIDER PWM 32-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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