- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄385522 > MAX1802 (Maxim Integrated Products, Inc.) Digital Camera Step-Down Power Supply PDF資料下載
參數(shù)資料
| 型號： | MAX1802 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | Digital Camera Step-Down Power Supply |
| 中文描述： | 數(shù)碼相機降壓型電源 |
| 文件頁數(shù)： | 19/28頁 |
| 文件大?。?/td> | 469K |
| 代理商： | MAX1802 |
第1頁第2頁第3頁第4頁第5頁第6頁第7頁第8頁第9頁第10頁第11頁第12頁第13頁第14頁第15頁第16頁第17頁第18頁當前第19頁第20頁第21頁第22頁第23頁第24頁第25頁第26頁第27頁第28頁
M
Digital Camera Step-Down
Power Supply
______________________________________________________________________________________
19
R
OSC
= (200ns - 1/f
OSC
) / (C
OSC
+ 10pF)
ln (1 - V
REF
/ V
VL
)
See the
Typical Operating Characteristics
for f
OSC
vs.
R
OSC
using different values of C
OSC
. Due to duty cycle
limitation in the main controller, keep f
OSC
≤
V
MAIN
/
(V
VDDM(MAX)
500ns).
Setting the Output Voltages
Set the MAX1802 output voltage of each converter by
connecting a resistive voltage-divider from the output
voltage to the corresponding FB_ input. The FB_ input
bias current is <100nA, so choose R
L
(the low-side
FB_-to-GND resistor) to be 100k
. Choose R
H
(the
high-side output-to-FB_ resistor) according to the rela-
tion:
Setting the Maximum Duty Cycle
The oscillator signal at OSC and the voltage at DCON_
are used to generate the internal clock signals for the
three MAX1802 auxiliary controllers (CLK in Figure 3).
The internal clock
’
s falling edge occurs when V
OSC
exceeds V
DCON
_ (set by a resistive divider). The inter-
nal clock
’
s rising edge occurs when V
OSC
falls below
0.25V (Figure 5).
The adjustable maximum duty cycle range is 40% to
90% (see Maximum Duty Cycle vs. V
DCON
_ in the
Typical Operating Characteristics
). The maximum duty
cycle defaults to 76% at 100kHz if V
DCON
_ is at or
above the voltage at V
REF
(1.25V) (see Default
Maximum Duty Cycle vs. Frequency in the
Typical
Operating Characteristics
). The controller shuts down if
V
DCON
_ is <0.3V.
Inductor Selection
Main and Core Step-Down Converters
MAX1802 main and core step-down converters offer
best efficiency when the inductor current is continuous.
For most designs, a reasonable inductor value (L
IDEAL
)
can be derived from the following equation, which sets
continuous peak-to-peak inductor current at 1/3 the DC
inductor current:
where D, the duty cycle, is given by:
In these equations, V
DSP
is the voltage drop across the
P-channel MOSFET switch, and V
DSN
is the voltage
drop across the N-channel MOSFET synchronous recti-
fier. Given L
IDEAL
, the consistent peak-to-peak inductor
current is 0.33 I
OUT
. The maximum inductor current is
1.17 I
OUT
.
Inductance values smaller than L
IDEAL
can be used;
however, the maximum inductor current will rise as L is
reduced, and a larger output capacitance will be
required to maintain the same output ripple. For stable
operation, the minimum inductance is limited by the
internal slope compensation. The minimum inductor
values for main and core are given by:
and
where R
DSP
is the on-resistance of the P-channel MOS-
FET switch, and D
MAX
= V
OUT
/ V
IN
.
Auxiliary Step-Up Controllers
The three MAX1802 auxiliary step-up controllers offer
best efficiency when the inductor current is continuous.
L
D
V
f
MIN CORE
(
MAX
OUT
OSC
)
.
.
=
1
0 5
0 13
L
D
V
0 013
R
f
MIN MAIN
(
MAX
OUT
.
DSP
OSC
)
.
=
1
0 5
D
V
V
V
V
V
OUT
DSN
+
IN
DSP
DSN
=
+
L
V
V
D
D
I
IDEAL
IN
DSP
OUT OSC
=
(
)
(
)
3
1
R
R
V
1 248
.
H
L
OUT
=
1
t
L
t
H
1.25
V
OSC
(V)
V
DCON_
0.25
0
CLK
t
H
t
L
+ t
H
D
MAX
=
Figure 5. Auxiliary Controller Internal Clock Signal Generation
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MAX1802EHJ | Digital Camera Step-Down Power Supply |
| MAX1804 | External Four-Input Feedback Integrator for Power Supplies |
| MAX1804EUB | External Four-Input Feedback Integrator for Power Supplies |
| MAX1809 | 3A, 1MHz, DDR Memory Termination Supply |
| MAX1809EEE | 3A, 1MHz, DDR Memory Termination Supply |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX1802EHJ | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 Step-Up Slave DC/DC Controller RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
| MAX1802EHJ+ | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 Step-Up Slave DC/DC Controller RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
| MAX1802EHJ+T | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 Step-Up Slave DC/DC Controller RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
| MAX1802EHJ-T | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 Step-Up Slave DC/DC Controller RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
| MAX1804EUB | 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 安裝風格:SMD/SMT 封裝 / 箱體:HPSO-8 封裝:Reel |
發(fā)布緊急采購，3分鐘左右您將得到回復。