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參數(shù)資料
| 型號(hào)： | DS14287 |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類(lèi)： | Timer or RTC |
| 英文描述： | 1 TIMER(S), REAL TIME CLOCK, PDIP24 |
| 封裝： | 0.740 INCH, ENCAPSULATED, DIP-24 |
| 文件頁(yè)數(shù)： | 2/16頁(yè) |
| 文件大?。?/td> | 312K |
| 代理商： | DS14287 |
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MAX774/MAX775/MAX776
the current limit for the first two pulses is set to one-half
the peak current limit. If those pulses bring the output
voltage into regulation, the voltage comparator keeps
the MOSFET off, and the current limit remains at one-half
the peak current limit. If the output voltage is out of
regulation after two consecutive pulses, the current limit
for the next pulse will equal the full current limit.
With heavy loads, the MOSFET first switches twice at
one-half the peak current value. Subsequently, it stays
on until the switch current reaches the full current limit,
and then turns off. After it is off for 2.3s, the MOSFET
switches on once more, and remains on until the switch
current again reaches its limit. This cycle repeats until
the output is in regulation.
A benefit of this control scheme is that it is highly effi-
cient over a wide range of input/output ratios and load
currents. Additionally, PFM converters do not operate
with constant-frequency switching, and have relaxed
stability criterion (unlike PWM converters). As a result,
their external components require smaller values.
With PFM converters, the output voltage ripple is not
concentrated at the oscillator frequency (as it is with
PWM converters). For applications where the ripple fre-
quency is important, the PWM control scheme must be
used. However, for many other applications, the smaller
capacitors and lower supply current of the PFM control
scheme make it the better choice. The output voltage
ripple with the MAX774/MAX775/MAX776 can be held
quite low. For example, using the circuit of Figure 2,
only 100mV of output ripple is produced when generat-
ing a -5V at 1A output from a +5V input.
Bootstrapped vs.
Nonbootstrapped Operation
Figures 2 and 3 are the standard application circuits
for bootstrapped mode, and Figure 4 is the circuit for
nonbootstrapped mode. Since EXT is powered by OUT,
using bootstrapped or nonbootstrapped mode will
directly affect the gate drive to the FET. EXT swings
from V+ to VOUT. In bootstrapped operation, OUT is
-5V/-12V/-15V or Adjustable, High-Efficiency,
Low IQ Inverting DC-to-DC Controllers
10
______________________________________________________________________________________
MAX774
MAX775
MAX776
OUT
V+
SHDN
CS
FB
EXT
GND
P
7
8
C2
0.1
F
R1
0.07
C1
150
F
6
5
2
3
1
REF
4
Q1
Si9435
1N5822/
MBR340
L1
22
H
C4
*
VIN
C3
0.1
F
VOUT
* MAX774 = 330F, 10V
MAX775, MAX776 = 120
F, 20V
PRODUCT
MAX774
MAX775
MAX776
OUTPUT
VOLTAGE (V)
-5
-12
-15
INPUT
VOLTAGE (V)
3 to 15
3 to 8
3 to 5
OUTPUT
CURRENT (A)
1
0.5
0.4
NOTE: Si9435 HAS VGS OF 20V MAX
MAX774
MAX775
MAX776
OUT
V+
SHDN
CS
FB
EXT
GND
P
7
8
R2
R3
0.07
C1
150
F
6
5
2
3
1
REF
4
Q1
Si9435
1N5822/
MBR340
L1
22
H
C4
*
VIN
C3
0.1
F
VOUT
C2
0.1
F
R1
* MAX774 = 330F, 10V
MAX775, MAX776 = 120
F, 20V
Figure 2. Bootstrapped Connection Using Fixed Output
Voltages
Figure 3. Bootstrapped Connection Using External Feedback
Resistors
Figure 4. Nonbootstrapped Operation (VIN > 4.5V)
MAX774
MAX775
MAX776
OUT
V+
SHDN
CS
FB
EXT
GND
P
7
8
R2
R3
0.07
C1
150
F
6
5
2
3
1
REF
4
Q1
Si9435
1N5822/
MBR340
L1
22
H
C4
*
VIN
C3
0.1
F
VOUT
C2
0.1
F
R1
* MAX774 = 330F, 10V
MAX775, MAX776 = 120
F, 20V
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| DS14287+ | 功能描述:實(shí)時(shí)時(shí)鐘 RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 總線(xiàn)接口:I2C 日期格式:DW:DM:M:Y 時(shí)間格式:HH:MM:SS RTC 存儲(chǔ)容量:64 B 電源電壓-最大:5.5 V 電源電壓-最小:1.8 V 最大工作溫度:+ 85 C 最小工作溫度: 安裝風(fēng)格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube |
| DS1-48-0001 | 功能描述:固定電感器 DS Storage choke 3.15A RoHS:否 制造商:AVX 電感:10 uH 容差:20 % 最大直流電流:1 A 最大直流電阻:0.075 Ohms 工作溫度范圍:- 40 C to + 85 C 自諧振頻率:38 MHz Q 最小值:40 尺寸:4.45 mm W x 6.6 mm L x 2.92 mm H 屏蔽:Shielded 端接類(lèi)型:SMD/SMT 封裝 / 箱體:6.6 mm x 4.45 mm |
| DS1-48-0002 | 功能描述:固定電感器 DS Storage choke 4A RoHS:否 制造商:AVX 電感:10 uH 容差:20 % 最大直流電流:1 A 最大直流電阻:0.075 Ohms 工作溫度范圍:- 40 C to + 85 C 自諧振頻率:38 MHz Q 最小值:40 尺寸:4.45 mm W x 6.6 mm L x 2.92 mm H 屏蔽:Shielded 端接類(lèi)型:SMD/SMT 封裝 / 箱體:6.6 mm x 4.45 mm |
| DS1-48-0003 | 制造商:Schurter Electronic Components 功能描述: |
| DS1-48-0004 | 制造商:Schurter Electronic Components 功能描述: |
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