- 您现在的位置：买卖IC网 > PDF目录15367 > MIC3809YMM TR (Micrel Inc)IC REG CTRLR ISO PWM CM 8-MSOP PDF资料下载
参数资料
| 型号： | MIC3809YMM TR |
| 厂商： | Micrel Inc |
| 文件页数： | 8/11页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR ISO PWM CM 8-MSOP |
| 标准包装： | 2,500 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 1MHz |
| 占空比： | 50% |
| 电源电压： | 2 V ~ 14 V |
| 降压： | 是 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 是 |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 8-TSSOP，8-MSOP（0.118"，3.00mm 宽） |
| 包装： | 带卷 (TR) |
| 其它名称： | MIC3809YMMTR MIC3809YMMTR-ND |
MIC3808/3809
Functional Diagram
Micrel
Overcurrent
FB
2
3.65V
COMP
1
CS
3
Peak Current
8
V DD
Comparator
0.75V
2.2V
2.0V
Error
Comparator
0.5V
14V
V DD OK
Amplifier
Oscillator
7
OUTA
S
Q
0.8V
R
PWM
Comparator
PWM
Latch
V DD —1V
S1
1.2R
S
Q
T
Q
S2
Q
R
/Q
R
0.5V
V DD
Soft Start
R
6
OUTB
Voltage
Reference
Slope = 1V/ms
4
RC
Figure 1. MIC3808 Block Diagram
5
GND
Functional Description
The MIC3808/9 is a high-speed power supply controller with
push-pull output drive capability. MIC3808 has a higher V DD
turn-on threshold and more hysteresis between V DD turn-on
and turn-off than the MIC3809. The outputs of the controller
operate in a push-pull fashion with a guaranteed dead time
between them. A block diagram of the MIC3808/9 controller
is shown in Figure 1.
V DD and Turn-on Sequence
The oscillator and output gate drive signals are disabled
when V DD is lower than the turn on threshold. Circuitry in the
output drivers eliminates glitching or random pulsing during
the start-up sequence. The oscillator is enabled when V DD is
applied and reaches the turn-on threshold. The V DD com-
parator also turns off the internal soft-start discharge FET,
slowly bringing up the COMP pin voltage.
The V DD pin is internally clamped. As V DD approaches this
clamp voltage, the V DD current will increase over the normal
current draw of the IC. Exceeding the V DD zener shunt
voltage may cause excessive power dissipation in the
MIC3808/9.
Soft-Start
The soft start feature helps reduce surge currents at the
power supply input source. An internal current source and
capacitor ramp up from 0V to near Vdd at a typical rate of
1V/ms. The softstart feature limits the output voltage of the
error amplifier at the COMP pin. As the softstart voltage rises,
it allows the COMP pin voltage to rise, which in turn allows the
duty cycle of the output drivers to increase. The internal
softstart voltage is discharged and remains discharged dur-
ing the following conditions:
1. The V DD voltage drops below the turn-off
threshold
2. The voltage on the CS pin exceeds the
overcurrent comparator threshold
Once the internal softstart discharge FET is turned on, it
cannot be turned off until the internal softstart voltage drops
down below 0.5V. This insures a clean restart.
Oscillator
The oscillator operates at twice the switching frequency of
either OUTA or OUTB. The oscillator generates a sawtooth
waveform on the RC pin. The rising edge of the waveform is
controlled by the external resistor/capacitor combination.
The fall time is set by the on-resistance of the discharge FET
(see Figure 2). The fall time sets the delay (dead time)
between the turn-off of one output driver and the turn-on of the
other driver. A toggle flip-flop insures that drive signals to
OUTA and OUTB are alternated and therefore insures a
maximum duty cycle of less than 50% for each output driver.
Graphs of component values vs. oscillator frequency and
dead time are shown in the typical characteristic section of
this specification.
MIC3808/3809
8
April 2005
相关PDF资料 |
PDF描述 |
|---|---|
| VE-B14-EV-F2 | CONVERTER MOD DC/DC 48V 150W |
| GCM28DRES | CONN EDGECARD 56POS .156 EYELET |
| 160-560MS | INDUCTOR RF CHIP .056UH 20% SMD |
| PM105-181K-RC | INDUCTOR POWER 180UH 10% SMD |
| UPM2A151MHD | CAP ALUM 150UF 100V 20% RADIAL |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MIC3811B-0152W-LF3 | 制造商:Wurth Electronics Inc 功能描述:MIC3811b Serie Through-Hole Intergrated RJ45 制造商:Wurth Elektronik 功能描述:MIC3811b Serie Through-Hole Intergrated RJ45 |
| MIC38121-5356X-LF3 | 制造商:WURTH 制造商全称:Wurth Elektronik GmbH & Co. KG, Germany. 功能描述:TRANSFORMER |
| MIC38150 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:HELDO? 1.5A High Efficiency Low Dropout Regulator |
| MIC38150_10 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:HELDO? 1.5A High Efficiency Low Dropout Regulator |
| MIC38150HYHL | 制造商:Micrel 功能描述:HELDO 1.5A High Eff LDO Regulator |
发布紧急采购，3分钟左右您将得到回复。