參數(shù)資料
型號(hào)： MAX1804
廠(chǎng)商： Maxim Integrated Products, Inc.
英文描述： External Four-Input Feedback Integrator for Power Supplies
中文描述： 外部四反饋輸入積分器，用于電源控制
文件頁(yè)數(shù)： 8/11頁(yè)
文件大?。?/td> 570K
代理商： MAX1804
M
External Four-Input Feedback Integrator for
Power Supplies
8
_______________________________________________________________________________________
inputs are disabled, OUT is high impedance. Connect
any unused input to GND.
Setting the Maximum Regulator Output
Voltage Increase
The ratio between the maximum guaranteed OUT cur-
rent of 10μA and the current in the regulator
’
s feedback
resistive divider determines the maximum increase. The
maximum increase in the regulator output voltage
depends on the regulator
’
s upper feedback resistor
(R
TOP
) and the sink current into OUT:
V
OUT
(MAX) = I
OUT
(MAX) x R
TOP
The maximum adjust current I
OUT
(MAX) can be further
limited with a resistor (R
OUT
) between OUT and the
feedback point of the regulator (see
Typical Operating
Circuit
):
I
OUT
(MAX) = V
FB
/ R
OUT
where V
FB
is the voltage at the regulator
’
s feedback
point.
Therefore:
V
OUT
(MAX) = V
FB
x R
TOP
/ R
OUT
and:
R
OUT
= V
FB
x R
TOP
/
V
OUT
(MAX)
Place the regulator
’
s feedback resistors and R
OUT
close to the regulator
’
s feedback pin to reduce noise
pickup at the regulator
’
s feedback point, which can
cause unstable switching in the regulator (Figure 5).
Shutdown Mode
SHDN
is a logic input that, when held low, places the
MAX1804 in its low-power shutdown mode, reducing
the supply current to 10nA (typ). The IN1
–
IN4, OUT,
and ADJ are high impedance when the MAX1804 is in
shutdown or when V+ is removed. Connect
SHDN
to
V+ for normal operation.
Undervoltage Lockout
The MAX1804 has an undervoltage lockout (UVLO) fea-
ture that deactivates the device when the supply volt-
age at V+ goes below 2.4V; IN1
–
IN4, OUT, and ADJ go
to high impedance and do not affect the regulator oper-
ation. Hysteresis holds the device in lockout until the
supply voltage at V+ rises above 2.6V.
Integrator Gain-Bandwidth Product
and Regulator Stability
The MAX1804 gain-bandwidth (GBW) product is set by
the external capacitor on COMP:
GBW = [4 x (IN_ transconductance)] / (2
π
C
COMP
)
The bandwidth is typically 40kHz with a 470pF capaci-
tor on COMP.
For system stability, the integrator GBW product is typi-
cally set below the regulator circuit
’
s crossover frequen-
cy, if known. Switching regulators typically have
crossover frequencies well below their switching frequen-
cies. Setting the MAX1804
’
s GBW product too high can
cause regulator loop instability, typically evidenced by
ringing after transients. Setting the GBW product unnec-
essarily low will slow the MAX1804
’
s loop response to
transients, although the regulator
’
s loop transient
response will remain unaffected (see Load Transient
Response in
Typical Operating Characteristics
).
Often the regulator
’
s crossover frequency varies with
load and is not easily found. If the regulator
’
s crossover
frequency is unknown, the MAX1804
’
s gain-bandwidth
product can be chosen empirically. Start with a fairly
low capacitor value (470pF is a good starting point)
and increase the value until the circuit is stable with all
loads. Then increase the value further to ensure design
margin. If transient response is unimportant, choose a
large COMP capacitor value (such as 2200pF), thereby
maximizing stability.
Figure 3. MAX1804 Used with Linear Regulator
COMP
ADJ
IN2
IN3
IN4
IN1
GND
V+
SET
10
μ
F
2200pF
R
300k
R
600k
I
LOAD
0 TO
500mA
FDV 304P
5V TO
11V
1.25V
REFERENCE
MAX1804
SHDN
10
μ
F
R
BOTTOM
GND
SET
OUT
IN
MAX603
OFF
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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(fēng)格:SMD/SMT 封裝 / 箱體:HPSO-8 封裝:Reel
MAX1804EUB+ 功能描述:電流和電力監(jiān)控器、調(diào)節(jié)器 Feedback Integrator for Power Supply 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
MAX1804EUB+T 功能描述:電流和電力監(jiān)控器、調(diào)節(jié)器 Feedback Integrator for Power Supply 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
MAX1804EUB-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
MAX1805EEE 制造商:Maxim Integrated Products 功能描述:
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