參數(shù)資料
型號(hào)： MAX1856
廠商： Maxim Integrated Products, Inc.
元件分類： 數(shù)字信號(hào)處理
英文描述： Replaced by TMS320C6202B : Fixed-Point Digital Signal Processor 352-FCBGA
中文描述： 寬輸入范圍、可同步的、PWM SLIC電源
文件頁(yè)數(shù)： 9/18頁(yè)
文件大?。?/td> 594K
代理商： MAX1856
Low-Dropout Regulator (LDO)
All MAX1856 functions, including EXT, are internally
powered from the on-chip, low-dropout 5V regulator.
The regulator input is at V
CC
, while its output is at LDO.
The V
CC
-to-LDO dropout voltage is typically 200mV
(300mV max at 12mA), so that when V
CC
is <5.2V,
V
LDO
is typically V
CC
- 200mV. When the LDO is in
dropout, the MAX1856 still operates with V
CC
as low as
3V (as long as the LDO exceeds 2.7V), but with
reduced amplitude FET drive at EXT. The maximum
V
CC
input voltage is 28V.
LDO can supply up to 12mA to power the IC, supply
gate charge through EXT to the external FET, and sup-
ply small external loads. When driving particularly large
FETs at high switching rates, little or no LDO current
may be available for external loads. For example, when
switched at 500kHz, a large FET with 20nC gate charge
requires 20nC
500kHz, or 10mA.
Soft-Start
The MAX1856 features a
“
digital
”
soft-start that is pre-
set and requires no external capacitor. Upon startup,
the peak inductor current increments from 1/5th of the
value set by R
CS
, to the full current-limit value in five
steps over 1024 cycles of f
OSC
or f
SYNC
. Additionally,
the oscillator runs at 1/3 the normal operating frequen-
cy (f
OSC
/3) until the output voltage reaches 20% of its
nominal value (V
FB
≤
1.0V). See the
Typical Operating
Characteristics
for a scope picture of the soft-start
operation. Soft-start is implemented: 1) when power is
first applied to the IC, 2) when exiting shutdown with
power already applied, and 3) when exiting undervolt-
age lockout. The MAX1856
’
s soft-start sequence does
not start until V
LDO
reaches 2.5V.
Design Procedure
The MAX1856 can operate within a wide input voltage
range from 3V to 28V. This allows it to be used with wall
adapters. In applications driven by low-power, low-cost
and low input and output ripple current requirements,
the MAX1856 flyback topology can be used to gener-
ate various levels of output voltages and multiple out-
puts.
Communications over the Internet interface with a stan-
dard telephone connection, which includes the
Subscriber Line Interface Circuit (SLIC). The SLIC
requires a negative power supply for the audio and
ringer functions. The circuits discussed here are
designed for these applications. The following design
discussions are related to the standard application cir-
M
Wide Input Range, Synchronizable,
PWM SLIC Power Supply
_______________________________________________________________________________________
9
CS
EXT
1
2
FB
LDO
FREQ
*INPUT
4.5V TO 24V
D1, D2: Central Semiconductor CMR1U-02
M1: International Rectifier IRLL2705
T1: Coiltronics CTX01-14853
R
OSC
200k
C4
1
μ
F
C
LDO
1
μ
F
R
CS
33m
C
IN
(2x) 10
μ
F
25V
GND
REF
V
CC
PGND
SYNC/SHDN
MAX1856
OUT2
-72V
M1
9
10
1
2
3
7
4
5
6
8
T1
D2
D1
C5
1nF
R6
100
R5
10
R4
470
R3
5.11k
R2
681k
R1
174k
C
REF
2.2
μ
F
C2
100
μ
F
Sanyo
100MV100AX
C1
330
μ
F
Sanyo
35MV330AX
C3
100pF
2
2
OUT1
-24V
C
FB
1nF
*INPUT RANGE LIMITED BY OUTPUT POWER REQUIREMENTS.
SEE
MAXIMUM OUTPUT POWER
AND
TYPICAL OPERATING CHARACTERISTICS
.
Figure 1. Standard Application Circuit
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX1856EUB 功能描述:電信線路管理 IC RoHS:否 制造商:STMicroelectronics 產(chǎn)品:PHY 接口類型:UART 電源電壓-最大:18 V 電源電壓-最小:8 V 電源電流:30 mA 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VFQFPN-48 封裝:Tray
MAX1856EUB+ 功能描述:電信線路管理 IC Synchronizable PWM SLIC Power Supply RoHS:否 制造商:STMicroelectronics 產(chǎn)品:PHY 接口類型:UART 電源電壓-最大:18 V 電源電壓-最小:8 V 電源電流:30 mA 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VFQFPN-48 封裝:Tray
MAX1856EUB+T 功能描述:電信線路管理 IC Synchronizable PWM SLIC Power Supply RoHS:否 制造商:STMicroelectronics 產(chǎn)品:PHY 接口類型:UART 電源電壓-最大:18 V 電源電壓-最小:8 V 電源電流:30 mA 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VFQFPN-48 封裝:Tray
MAX1856EUB-T 功能描述:電信線路管理 IC RoHS:否 制造商:STMicroelectronics 產(chǎn)品:PHY 接口類型:UART 電源電壓-最大:18 V 電源電壓-最小:8 V 電源電流:30 mA 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VFQFPN-48 封裝:Tray
MAX1856EVKIT 功能描述:電源管理IC開發(fā)工具 Evaluation Kit for the MAX1856 RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評(píng)估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V
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