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参数资料
| 型号： | MC33341 |
| 厂商： | Motorola, Inc. |
| 英文描述： | Power Supply Battery Charger Regulation Control Circuit(应用于电源和电池充电器的稳压控制电路) |
| 中文描述： | 电源电池充电器规控制电路（应用于电源和电池充电器的稳压控制电路） |
| 文件页数： | 6/20页 |
| 文件大小： | 369K |
| 代理商： | MC33341 |
MC33341
6
MOTOROLA ANALOG IC DEVICE DATA
INTRODUCTION
Power supplies and battery chargers require precise
control of output voltage and current in order to prevent
catastrophic damage to the system load. Many present day
power sources contain a wide assortment of building blocks
and glue devices to perform the required sensing for proper
regulation. Typical feedback loop circuits may consist of a
voltage and current amplifier, level shifting circuitry, summing
circuitry and a reference. The MC33341 contains all of these
basic functions in a manner that is easily adaptable to many
of the various power source–load configurations.
OPERATING DESCRIPTION
The MC33341 is an analog regulation control circuit that is
specifically designed to simultaneously close the voltage and
current feedback loops in power supply and battery charger
applications. This device can control the feedback loop in
either constant–voltage or constant–current mode with
automatic crossover. A concise description of the integrated
circuit blocks is given below. Refer to the block diagram in
Figure 13.
Transconductance Amplifier
A quad input transconductance amplifier is used to control
the feedback loop. This amplifier has separate voltage and
current channels, each with a sense and a threshold input.
Within a given channel, if the sense input level exceeds that
of the threshold input, the amplifier output is driven high. The
channel with the largest difference between the sense and
threshold inputs will set the output source current of the
amplifier and thus dominate control of the feedback loop. The
amplifier output appears at Pin 8 and is a source–only type
that is capable of 15 mA.
A high impedance node within the transconductance
amplifier is made available at Pin 3 for loop compensation.
This pin can sink and source up to 10
μ
A of current. System
stability is achieved by connecting a capacitor from Pin 3 to
ground. The Compensation Pin signal is out of phase with
respect to the Drive Output. By actively clamping Pin 3 low,
the Drive Output is forced into a high state. This, in effect, will
shutdown the power supply or battery charger, by forcing the
output voltage and current regulation threshold down
towards zero.
Voltage Sensing
The voltage that appears across the load is monitored by
the noninverting Vsen input of the transconductance amplifier.
This voltage is resistively scaled down and connected to
Pin 5. The threshold at which voltage regulation occurs is set
by the level present at the inverting Vth input of the
transconductance amplifier. This level is controlled by Pin 6.
In source high–side and load high–side current sensing
modes, Pin 6 must be connected to the low potential side of
current sense resistor RS. Under these conditions, the
voltage regulation threshold is internally fixed at 1.2 V. In
source return low–side and load low–side current sensing
modes, Pin 6 is available, and can be used to lower the
regulation threshold of Pin 5. This threshold can be externally
adjusted over a range of 0 V to 1.2 V with respect to the IC
ground at Pin 4.
Current Sensing
Current sensing is accomplished by monitoring the
voltage that appears across sense resistor RS, level shifting
it with respect to Pin 4 if required, and applying it to the
noninverting Isen input of the transconductance amplifier. In
order to allow for maximum circuit flexibility, there are three
methods of current sensing, each with different internal
paths.
In source high–side (Figures 13 and 14) and load high–side
(Figures 17 and 18) current sensing, the Differential Amplifier
is active with a gain of 1.0. Pin 1 connects to the high potential
side of current sense resistor RS while Pin 6 connects to the
low side. Logic circuitry is provided to disable the Differential
Amplifier output whenever low–side current sensing is
required. This circuit clamps the Differential Amplifier output
high which disconnects it from the Isen input of the
Transconductance Amplifier. This happens if Pin 1 is less than
1.2 V or if Pin 1 is less than Pin 6.
With source return low–side current sensing (Figures 15
and 16), the Inverting Amplifier is active with a gain of –1.0.
Pin 1 connects to the low potential side of current sense
resistor RS while Pin 4 connects to the high side. Note that a
negative voltage appears across RS with respect to Pin 4.
In load low–side current sensing (Figures 19 and 20) a
Noninverting input path is active with a gain of 1.0. Pin 1
connects to the high potential side of current sense resistor
RS while Pin 4 connects to the low side. The Noninverting
input path lies from Pin 1, through the Inverting Amplifier
input and feedback resistors R, to the cathode of the output
diode. With load low–side current sensing, Pin 1 will be more
positive than Pin 4, forcing the Inverting Amplifier output low.
This causes the diode to be reverse biased, thus preventing
the output stage of the amplifier from loading the input signal
that is flowing through the feedback resistors.
The regulation threshold in all of the current sensing
modes is internally fixed at 200 mV with Pin 2 connected to
VCC. Pin 2 can be used to externally adjust the threshold over
a range of 0 to 200 mV with respect to the IC ground at Pin 4.
Reference
An internal band gap reference is used to set the 1.2 V
voltage threshold and 200 mV current threshold. The
reference is initially trimmed to a
±
1.0% tolerance at
TA = 25
°
C and is guaranteed to be within
±
2.0% over an
ambient operating temperature range of –25
°
to 85
°
C.
Applications
Each of the application circuits illustrate the flexibility of
this device. The circuits shown in Figures 13 through 20
contain an optoisolator connected from the Drive Output at
Pin 8 to ground. This configuration is shown for ease of
understanding and would normally be used to provide an
isolated control signal to a primary side switching regulator
controller. In non–isolated, primary or secondary side
applications, a load resistor can be placed from Pin 8 to
ground. This resistor will convert the Drive Output current to
a voltage for direct control of a regulator.
In applications where excessively high peak currents are
possible from the source or load, the load induced voltage
drop across RS could exceed 1.6 V. Depending upon the
current sensing configuration used, this will result in forward
biasing of either the internal VCC clamp diode, Pin 6, or the
device substrate, Pin 1. Under these conditions, input series
resistor R3 is required. The peak input current should be
limited to 20 mA. Excessively large values for R3 will
degrade the current sensing accuracy. Figure 21 shows a
method of bounding the voltage drop across RS without
sacrificing current sensing accuracy.
相关PDF资料 |
PDF描述 |
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| MC33341 | POWER SUPPLY BATTERY CHARGER REGULATION CONTROL CIRCUIT |
| MC33341D | POWER SUPPLY BATTERY CHARGER REGULATION CONTROL CIRCUIT |
| MC33341P | POWER SUPPLY BATTERY CHARGER REGULATION CONTROL CIRCUIT |
| MC33348D-1 | LITHIUM BATTERY PROTECTION CIRCUIT FOR ONE CELL SMART BATTERY PACKS |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MC33341D | 功能描述:电池管理 2.3-15V Power Supply RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
| MC33341DG | 功能描述:电池管理 2.3-15V Power Supply Charger w/Regulation RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
| MC33341DR2 | 功能描述:电池管理 2.3-15V Power Supply RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
| MC33341DR2G | 功能描述:电池管理 2.3-15V Power Supply Charger w/Regulation RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
| MC33341P | 功能描述:电池管理 2.3-15V Power Supply RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
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