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| 型号： | MIC9131YM TR |
| 厂商： | Micrel Inc |
| 文件页数： | 10/19页 |
| 文件大小： | 0K |
| 描述： | IC CTRLR DC-DC PWM HV HS 16-SOIC |
| 标准包装： | 2,500 |
| 应用： | 控制器，电信 |
| 输入电压： | 9 V ~ 18 V |
| 输出数： | 1 |
| 输出电压： | 4.7 V ~ 5 V |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-SOIC（0.154"，3.90mm 宽） |
| 供应商设备封装： | 16-SOIC |
| 包装： | 带卷 (TR) |
| 其它名称： | MIC9131YMTR MIC9131YMTR-ND |
Ct = 470pF
t
MIC9131
plied and the depletion FET, which is normally enabled allows
current from V IN to charge the V CC bias capacitor. Once the
V CC voltage reaches the V CC enable threshold, V GLO (ON) ,
the gate drive is enabled and the MIC9131 starts switching.
Vcc continues to increase until the Pre-Regulator turn-off
threshold, (V PR (OFF)), is reached and the depletion FET is
turned off. The Vcc voltage decreases as energy from the
bias capacitor is used to supply the controller. The deple-
tion FET is turned back on when the pre-regulator turn-on
threshold is reached. A bias winding derived supply voltage,
set higher than the FET turn-off threshold, V PR (OFF), raises
the V CC voltage over the threshold and prevents the FET
from turning on.
In certain designs the MIC9131 may be powered directly from
the Line voltage, eliminating the need for an extra transformer
bias winding. When operating in this fashion the designer
must insure the power dissipation in the IC does not cause
the die temperature to exceed the 125°C maximum. Power
dissipation is calculated by:
P DISS = ( V IN ? V CC ) × I VCC
Where :
V IN is the line input voltage
V CC is the average V CC voltage (typically 8.5V)
I VCC is the total current drawn by the IC
I VCC is the sum of the operating current of the MIC9131 at
a given frequency and the average current required to drive
the external switching MOSFET. A plot of typical operating
current vs. frequency is given in Figure 3. The average MOS-
FET gate drive current is calculated in the “MOSFET GATE
DRIVE” section of this speci?cation.
Quiescent Current
vs. Frequency
10
9
8
7
6
5
4
3
2 C = 100pF
1
0
GATE DRIVE FREQUENCY (kHz)
Figure 3
The die junction temperature is calculated by
T J = T A + P DISS × θ JA
Where: T J is the die junction temperature
T A is the ambient temperature of the circuit
θ JA is the junction to ambient thermal resistance
of the MIC9131 (listed in the operating ratings
section of the speci?cation.
When powered directly from the Line voltage, the V CC volt-
age will vary between the upper and lower pre-regulator
thresholds. The amplitude of the output gate drive voltage
will vary with the V CC voltage. This should not be a problem
for most topologies since the variation is small (equal to the
Micrel, Inc.
ΔV PR hysteresis). The bias regulator in the MIC9131 buffers
the internal circuits from V CC variations.
The pre-regulator FET is protected by a thermal shutdown
circuit, which turns the MOSFET off if its temperature exceeds
approximately 150°C.
When operating at input voltages greater than 150V, a fast
input voltage risetime during turn-on (which may occur during
a hot plug operation)may cause a high peak current to ?ow
through the depletion FET, damaging the MIC9131. A 1.8kΩ
resistor in series between the input voltage and the Line pin
(pin 1) is recommended when operating at input voltages
greater than 150V. This resistor limits the maximum peak
current to 100mA (at 180V IN ) and protects the part.
The depletion mode MOSFET contains an internal parasitic
diode. The V IN pin voltage must be greater than the V CC
voltage or the V CC voltage will be clamped to a diode drop
greater than the V IN voltage. Excessive power dissipation
in the parasitic diode will destroy the IC.
V CC and Bias Supplies
The power for the controller and gate drive circuitry is supplied
through the V CC pin. The gate drive current is returned to
ground through the power ground pin (PGND). The rest of
the supply current is returned to ground through the analog
ground pin (AGND). The two ground pins must be connected
together through the PCB ground plane.
High frequency decoupling is provided at the V CC pin to supply
the gate drive’s peak current requirements. Turn-on of the
external MOSFET causes a voltage glitch on the V CC pin. If
the glitch is excessive, this disruption can appear as noise or
jitter in the oscillator circuit or the gate drive waveform. The
decoupling capacitor must be able to supply the MOSFET
gate with the charge required to turn it on. A 0.1μF ceramic
capacitor is usually suf?cient for most MOSFETs. Larger
FETs, with a higher gate charge requirement may require a
0.22μF ceramic capacitor or a ceramic capacitor paralleled
with a 2.2μF tantalum or 4.7uF aluminum electrolytic. It is
recommend that if V LINE is greater than 150V DC than the
maximum capacitor recommended on V CC is 2.2μF.The ca-
pacitor must be located next to the V CC pin of the MIC9131.
The ground end of the capacitor should be connected to the
ground plane, making a low impedance connection to the
power ground pin (pin 15).
The internal bias regulator block provides several internal and
external bias voltages. Referring to Figure 1, a 2.5V refer-
ence is used for the internal error ampli?er, a 0.82V bias is
used by the current limit comparator and a 1.21V reference
is used by the Line UVLO circuit. An external 5V bias volt-
age (V BIAS ) powers the oscillator circuit and may be used
as a reference voltage for other external components. The
V BIAS pin requires a minimum 0.1μF capacitor to ground for
decoupling.
Enable and Undervoltage Monitoring Circuits
The two undervoltage lockout circuits in the MIC9131 are
shown in Figure 4. One monitors the V CC voltage and the
other monitors the input line voltage. These signals are OR’d
together and either one can disable the gate drive pin and
discharge the voltage on the soft start capacitor.
M9999-080206
10
August 2006
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| MIC9131YQS | 功能描述:电流型 PWM 控制器 SO-16 High Vin Telecom DC/DC PWM Control IC (Lead Free) RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| MIC9131YQS TR | 功能描述:电流型 PWM 控制器 SO-16 High Vin Telecom DC/DC PWM Control IC (Lead Free) RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| MIC913BM5 | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| MIC913BM5 TR | 功能描述:IC OPAMP 350MHZ HS LP SOT23-5 RoHS:否 类别:集成电路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 标准包装:2,500 系列:- 放大器类型:通用 电路数:1 输出类型:满摆幅 转换速率:0.11 V/µs 增益带宽积:350kHz -3db带宽:- 电流 - 输入偏压:4nA 电压 - 输入偏移:20µV 电流 - 电源:260µA 电流 - 输出 / 通道:20mA 电压 - 电源，单路/双路(±):2.7 V ~ 36 V，±1.35 V ~ 18 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 供应商设备封装:8-SO 包装:带卷 (TR) |
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