- 您现在的位置：买卖IC网 > PDF目录67658 > GM3255S8R (American Power Management Inc.) 1.5A 280kHz DC-DC CONVERTOR BOOST REGULATOR PDF资料下载
参数资料
| 型号： | GM3255S8R |
| 厂商： | American Power Management Inc. |
| 元件分类： | DC/DC变换器 |
| 英文描述： | 1.5A 280kHz DC-DC CONVERTOR BOOST REGULATOR |
| 中文描述： | 1.5A的为280kHz的DC - DC转换器升压稳压器 |
| 文件页数： | 2/19页 |
| 文件大小： | 234K |
| 代理商： | GM3255S8R |
The situation is different in a flyback circuit. The input
current is discontinuous and a significant pulse cur-
rent is see by the input capacitors. Therefore, there
are two requirements for capacitors in a flyback regu-
lator: energy storage and filtering. To maintain a sta-
ble voltage supply to the chip, a storage capacitor
larger than 20F with low ESR is required. To reduce
the noise generated by the inductor, insert a 1.0F ce-
ramic capacitor between V
and ground as close as
CC
possible to the chip.
When the power switch is turned on, I
is shunted to
L
ground and I
discharges the output capacitor.
OUT
When the I ripple is small enough, I can be treated
LL
as a constant and is equal to input current I ,
IN
Summing up, the output voltage peak-peak ripple can
be calculated by:
The equation can be expressed more conveniently in
terms of V
, V
and I
for design purposes as
CC
OUT
follows:
The capacitor RMS ripple current is:
Although the above equations apply only for boost cir-
cuits, similar equations can be derived for flyback cir-
cuits.
+
-
Figure 11. Boost Circuit Effective Input Filter
VCC
CIN
RESR
IL
IIN
Reducing the Current Limit
In some applications, the designer may prefer a lower
limit on the switch current than 1.5A. An external shunt
can be connected between the V pin and ground to re-
C
duce its clamp voltage. Consequently, the current limit
of the internal power transistor current is reduced from
its nominal value.
The voltage on the V
pin can be evaluated with the
C
equation
where:
R
= 0.063 W, the value of the internal emitter resistor;
E
A
= 5V/ V, the gain of the current sense amplifier
.
V
Since R
and A
cannot be changed by the end user,
the only available method for limiting switch current be-
low 1.5A is to clamp the V pin at a lower voltage. If
C
the maximum switch or inductor current is substituted
into the equation above, the desired clamp voltage will
result.
A simple diode clamp, as shown in Figure12, clamps
the V voltage to a diode drop above the voltage on re-
C
sistor R3. Unfortunately, such a simple circuit is not
generally acceptable if V
is loosely regulated.
IN
V
=
OUT(RIPPLE)
+
+ I X ESR
IN
(I - I
) (1 - D)
IN
OUT
(C
)(f)
OUT
ID
OUT
(C
)(f)
OUT
V
=
x
OUT(RIPPLE)
+
I(V
- V
)
OUT
CC
(C
)(f)
OUT
(I
)(V
)(ESR)
OUT
V
CC
1
(C
)(f)
OUT
22
(I
- I
) (1 - D) + (I
) (D)
IN
OUT
V
- V
OUT
CC
V
CC
I
=
RIPPLE
= I
OUT
V
= I
R A
CSW E V
Figure 12. Current Limiting using a Diode Clamp
VC
D1
VCC
R1
V IN
C2
C1
R2
R3
G
M
3
2
5
10
E
V
相关PDF资料 |
PDF描述 |
|---|---|
| GM3255S8T | 1.5A 280kHz DC-DC CONVERTOR BOOST REGULATOR |
| GM3255 | 1.5A 280kHz DC-DC CONVERTOR BOOST REGULATOR |
| GM34063D8T | 1.5A DC-TO-DC CONVERTER CONTROL CIRCUIT |
| GM34063S8R | 1.5A DC-TO-DC CONVERTER CONTROL CIRCUIT |
| GM34063S8T | 1.5A DC-TO-DC CONVERTER CONTROL CIRCUIT |
相关代理商/技术参数 |
参数描述 |
|---|---|
| GM3255S8T | 制造商:GAMMA 制造商全称:GAMMA 功能描述:1.5A 280kHz DC-DC CONVERTOR BOOST REGULATOR |
| GM330K | 制造商:Mallory Sonalert Products Inc 功能描述:Cap Ceramic 33pF 500V SL 10% (6 X 4mm) Radial 6.4mm 85°C 制造商:CORNELL DUBILIER ELECTRONICS 功能描述:Cap Ceramic 33pF 500V SL 10% (6 X 4mm) Radial 6.4mm 85°C |
| GM331K | 功能描述:瓷片电容器 500V 330pF DISC RoHS:否 制造商:Vishay/Cera-Mite 电容:0.01 uF 容差:20 % 电压额定值:3 kV 工作温度范围:- 25 C to + 105 C 损耗因数 DF: 端接类型:Radial 产品:High Voltage Ceramic Disc Capacitors |
| GM3326 | 制造商:GAMMA 制造商全称:GAMMA 功能描述:PWM,PWM/PFM SWITCHING STEP-UP & DOWN DC/DC CONVERTER CONTROLLER ICS |
| GM3326-2.5ST25R | 制造商:GAMMA 制造商全称:GAMMA 功能描述:PWM,PWM/PFM SWITCHING STEP-UP & DOWN DC/DC CONVERTER CONTROLLER ICS |
发布紧急采购，3分钟左右您将得到回复。