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参数资料
型号： MAX1845EEI
厂商： MAXIM INTEGRATED PRODUCTS INC
元件分类： 稳压器
英文描述： Dual, High-Efficiency, Step-Down Controller with Accurate Current Limit
中文描述： DUAL SWITCHING CONTROLLER, 620 kHz SWITCHING FREQ-MAX, PDSO28
封装： 0.150 INCH, 0.025 INCH PITCH, MO-137AD, QSOP-28
文件页数： 12/27页
文件大小： 543K
代理商： MAX1845EEI
M
Two external factors that influence switching-frequency
accuracy are resistive drops in the two conduction
loops (including inductor and PC board resistance) and
the dead-time effect. These effects are the largest con-
tributors to the change of frequency with changing load
current. The dead-time effect increases the effective
on-time, reducing the switching frequency as one or
both dead times. It occurs only in PWM mode (
SKIP
=
high) when the inductor current reverses at light or neg-
ative load currents. With reversed inductor current, the
inductor
’
s EMF causes LX to go high earlier than nor-
mal, extending the on-time by a period equal to the
low-to-high dead time.
For loads above the critical conduction point, the actual
switching frequency is:
V
t
V
ON
IN
(
where V
DROP
1 is the sum of the parasitic voltage drops
in the inductor discharge path, including synchronous
rectifier, inductor, and PC board resistances; V
DROP2
is
the sum of the resistances in the charging path; and
t
ON
is the on-time calculated by the MAX1845.
Automatic Pulse-Skipping Switchover
In skip mode (
SKIP
= GND), an inherent automatic
switchover to PFM takes place at light loads. This
switchover is effected by a comparator that truncates
the low-side switch on-time at the inductor current
’
s
zero crossing. This mechanism causes the threshold
between pulse-skipping PFM and nonskipping PWM
operation to coincide with the boundary between con-
tinuous and discontinuous inductor-current operation
(also known as the critical conduction point). For a 7V
to 24V battery range, of this threshold is relatively con-
stant, with only a minor dependence on battery voltage:
K
V
2L
I
V
-V
V
LOAD(SKIP)
OUT_
IN
OUT_
IN
≈
×
f
V
V
OUT
DROP
DROP
=
+
+
)
1
2
Dual, High-Efficiency, Step-Down
Controller with Accurate Current Limit
12
______________________________________________________________________________________
Table 1. Component Selection for
Standard Applications
Table 2. Component Suppliers
*Distributor
COMPONENT
SIDE 1: 1.8V AT 8A/
SIDE 2: 2.5V AT 4A
Input Range
4.5V to 28V
Q1 High-Side MOSFET
Fairchild Semiconductor
FDS6612A or
International Rectifier
IRF7807
Q2 Low-Side MOSFET
Fairchild Semiconductor
FDS6670A or
International Rectifier
IRF7805
Q3, Q4 High/Low-Side
MOSFETs
Fairchild Semiconductor
FDS6982A
D1, D2 Rectifier
Nihon EP10QY03
D3 Rectifier
Central Semiconductor
CMPSH-3A
L1 Inductor
2.2μH
Panasonic ETQP6F2R2SFA
or
Sumida CDRH127-2R4
L2 Inductor
4.7μH
Sumida CDRH124-4R7MC
C1 (3), C2 (2) Input
Capacitor
10μF, 25V
Taiyo Yuden
TMK432BJ106KM or
TDK C4532X5R1E106M
C3 (3), C4 Output Capacitor
470μF, 6V
Kemet T510X477M006AS or
Sanyo 6TPB330M
R
SENSE1
5m
, ±1%, 1W
IRC LR2512-01-R005-F or
D
ALE
WSL-2512-R005F
R
SENSE2
10m
, ±1%, 0.5W
IRC LR2010-01-R010-F or
D
ALE
WSL-2010-R010F
MANUFACTURER
USA PHONE
FACTORY FAX
[Country Code]
[1] 516-435-1824
[1] 203-452-5670
[1] 408-721-1635
[1] 310-322-3332
[1] 828-264-7204
[1] 408-986-1442
[81] 3-3494-7414
[81] 7-2070-1174
Central Semiconductor
Dale/Vishay
Fairchild Semiconductor
International Rectifier
IRC
Kemet
NIEC (Nihon)
Sanyo
516-435-1110
203-452-5664
408-822-2181
310-322-3331
800-752-8708
408-986-0424
805-867-2555*
619-661-6835
408-988-8000
800-554-5565
847-956-0666
408-573-4150
847-390-4461
Siliconix
[1] 408-970-3950
Sumida
Taiyo Yuden
TDK
[81] 3-3607-5144
[1] 408-573-4159
[1] 847-390-4405
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相关代理商/技术参数
参数描述
MAX1845EEI+ 功能描述:电流型 PWM 控制器 Step-Down Controller RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14
MAX1845EEI+T 功能描述:电流型 PWM 控制器 Step-Down Controller RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14
MAX1845EEI-T 功能描述:电流型 PWM 控制器 RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14
MAX1845EEI-TG05 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述:
MAX1845EEI-TG068 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述:
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