參數(shù)資料
型號(hào)： MAX1537ETX
廠商： MAXIM INTEGRATED PRODUCTS INC
元件分類(lèi)： 穩(wěn)壓器
英文描述： High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers
中文描述： SWITCHING CONTROLLER, 500 kHz SWITCHING FREQ-MAX, QCC36
封裝： 6 X 6 MM, 0.8 MM HEIGHT, MO-220WJJD-1, TQFN-36
文件頁(yè)數(shù)： 33/38頁(yè)
文件大?。?/td> 763K
代理商： MAX1537ETX
M
High-Efficiency, 5x Output, Main Power-Supply
Controllers for Notebook Computers
______________________________________________________________________________________
33
Switching losses in the high-side MOSFET can become
a heat problem when maximum AC-adapter voltages
are applied, due to the squared term in the switching-
loss equation (C x V
IN
2
x f
SW
). If the high-side MOSFET
chosen for adequate R
DS(ON)
at low battery voltages
becomes extraordinarily hot when subjected to
V
IN(MAX)
, consider choosing another MOSFET with
lower parasitic capacitance.
For the low-side MOSFET (N
L
), the worst-case power
dissipation always occurs at maximum battery voltage:
The absolute worst case for MOSFET power dissipation
occurs under heavy-overload conditions that are
greater than I
LOAD(MAX)
but are not high enough to
exceed the current limit and cause the fault latch to trip.
To protect against this possibility, “overdesign” the cir-
cuit to tolerate:
where I
LIMIT
is the peak current allowed by the current-
limit circuit, including threshold tolerance and sense-
resistance variation. The MOSFETs must have a
relatively large heatsink to handle the overload power
dissipation.
Choose a Schottky diode (D
L
) with a forward-voltage
drop low enough to prevent the low-side MOSFET’s
body diode from turning on during the dead time. As a
general rule, select a diode with a DC current rating
equal to 1/3rd the load current. This diode is optional
and can be removed if efficiency is not critical.
Boost Capacitors
The boost capacitors (C
BST
) must be selected large
enough to handle the gate-charging requirements of
the high-side MOSFETs. Typically, 0.1μF ceramic
capacitors work well for low-power applications driving
medium-sized MOSFETs. However, high-current appli-
cations driving large, high-side MOSFETs require boost
capacitors larger than 0.1μF. For these applications,
select the boost capacitors to avoid discharging the
capacitor more than 200mV while charging the high-
side MOSFETs’ gates:
where Q
GATE
is the total gate charge specified in the
high-side MOSFET’s data sheet. For example, assume
the FDS6612A n-channel MOSFET is used on the high
side. According to the manufacturer’s data sheet, a sin-
gle FDS6612A has a maximum gate charge of 13nC
(V
GS
= 5V). Using the above equation, the required
boost capacitance is:
Selecting the closest standard value. This example
requires a 0.1μF ceramic capacitor.
Applications Information
Duty-Cycle Limits
Minimum Input Voltage
The minimum input operating voltage (dropout voltage)
is restricted by the maximum duty-cycle specification
(see the
Electrical Characteristics
table). However,
keep in mind that the transient performance gets worse
as the step-down regulators approach the dropout volt-
age, so bulk output capacitance must be added (see
the voltage sag and soar equations in the
Design
Procedure
section). The absolute point of dropout
occurs when the inductor current ramps down during
the off-time (
I
DOWN
) as much as it ramps up during
the on-time (
I
UP
). This results in a minimum operating
voltage defined by the following equation:
where V
CHG
and V
DIS
are the parasitic voltage drops in
the charge and discharge paths, respectively. A rea-
sonable minimum value for h is 1.5, while the absolute
minimum input voltage is calculated with h = 1.
Maximum Input Voltage
The MAX1533/MAX1537 controllers include a minimum
on-time specification, which determines the maximum
input operating voltage that maintains the selected
switching frequency (see the
Electrical Characteristics
table). Operation above this maximum input voltage
results in pulse-skipping operation, regardless of the
operating mode selected by
SKIP
. At the beginning of
each cycle, if the output voltage is still above the feed-
V
V
V
h
D
V
V
IN MIN
(
OUT
CHG
MAX
OUT
DIS
)
+
+
+
=
(
)
1
1
-
C
nC
mV
F
BST
=
=
0 065
μ
13
200
C
Q
mV
BST
GATE
=
200
I
I
I
LOAD
LIMIT
INDUCTOR
2
=
-
PD N
sistive
V
V
I
R
L
OUT
IN MAX
(
LOAD
DS ON
(
(
Re
)
)
)
=
(
)
1
2
-
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX1537ETX-T 功能描述:電流和電力監(jiān)控器、調(diào)節(jié)器 RoHS:否 制造商:STMicroelectronics 產(chǎn)品:Current Regulators 電源電壓-最大:48 V 電源電壓-最小:5.5 V 工作溫度范圍:- 40 C to + 150 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:HPSO-8 封裝:Reel
MAX1537EVKIT 制造商:Maxim Integrated Products 功能描述:MAIN POWER SUPPLY CONTROLLER FOR NOTEBOOK - Bulk
MAX1538ETI 功能描述:電池管理 RoHS:否 制造商:Texas Instruments 電池類(lèi)型:Li-Ion 輸出電壓:5 V 輸出電流:4.5 A 工作電源電壓:3.9 V to 17 V 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:VQFN-24 封裝:Reel
MAX1538ETI+ 功能描述:電池管理 Power-Source Select for Dual-Bat System RoHS:否 制造商:Texas Instruments 電池類(lèi)型:Li-Ion 輸出電壓:5 V 輸出電流:4.5 A 工作電源電壓:3.9 V to 17 V 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:VQFN-24 封裝:Reel
MAX1538ETI+T 功能描述:電池管理 Power-Source Select for Dual-Bat System RoHS:否 制造商:Texas Instruments 電池類(lèi)型:Li-Ion 輸出電壓:5 V 輸出電流:4.5 A 工作電源電壓:3.9 V to 17 V 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:VQFN-24 封裝:Reel
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