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參數(shù)資料
| 型號： | MC44602P2 |
| 廠商： | MOTOROLA INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | RV Series - Econoline Unregulated DC-DC Converters; Input Voltage (Vdc): 3.3V; Output Voltage (Vdc): 12V; Power: 2W; High Isolation 2W Converter; Approved for Medical Applications; EN and UL Safety Certificates; 6kVDC Isolation; Skinny DIP24 Package; Optional Continuous Short Circuit Protected; Fully Encapsulated; Very Low Isolation Capacitance |
| 中文描述： | 1.5 A SWITCHING CONTROLLER, 500 kHz SWITCHING FREQ-MAX, PDIP16 |
| 封裝： | PLASTIC, DIP-16 |
| 文件頁數(shù)： | 10/18頁 |
| 文件大?。?/td> | 332K |
| 代理商： | MC44602P2 |
MC44602
10
MOTOROLA ANALOG IC DEVICE DATA
OPERATING DESCRIPTION
The MC44602 is a high performance, fixed frequency,
current mode controller specifically designed to directly drive
a bipolar power switch in off–line and high voltage dc–to–dc
converter applications. This device offers the designer a cost
effective solution with minimal external components. The
representative block and timing diagrams are shown in
Figures 27 and 28.
Oscillator
The oscillator frequency is programmed by the values
selected for the timing components RT and CT. Capacitor CT
is charged from the 5.0 V reference through resistor RT to
approximately 2.8 V and discharged to 1.2 V by an internal
current sink. During the discharge of CT, the oscillator
generates an internal blanking pulse that holds one of the
inputs of the NOR gate high. This causes the Source and
Sink outputs to be in a low state, thus producing a controlled
amount of output deadtime. An internal toggle flip–flop has
been incorporated in the MC44602 which blanks the output
off every other clock cycle by holding one of the inputs of the
NOR gate high. This in combination with the CT discharge
period yields output deadtimes programmable from 50% to
70%. Figure 1 shows RT versus Oscillator Frequency and
Figure 2, Output Deadtime versus Frequency, both for a
given value of CT. Note that many values of RT and CT will
give the same oscillator frequency but only one combination
will yield a specific output deadtime at a given frequency.
In many noise sensitive applications it may be desirable to
frequency–lock the converter to an external system clock.
This can be accomplished by applying a narrow rectangular
clock signal with an amplitude of 3.2 V to 5.5 V to the Sync
Input (Pin 7). For reliable locking, the free–running oscillator
frequency should be set about 10% less than the clock
frequency. If the clock signal is ac coupled through a
capacitor, an external clamp diode may be required if the
negative sync input current is greater than –5.0 mA.
Connecting Pin 7 to Vref will cause CT to discharge to 0 V,
inhibiting the Oscillator and conduction of the Source Output.
Multi–unit synchronization can be accomplished by
connecting the CT pin of each IC to a single MC1455 timer.
Error Amplifier
A fully compensated Error Amplifier with access to the
inverting input and output is provided. It features a typical dc
voltage gain of 90 dB, and a unity gain bandwith of
1.0 MHz with 57 degrees of phase margin (Figure 7). The
noninverting input is internally biased at 2.5 V and is not
pinned out. The converter output voltage is typically divided
down and monitored by the inverting input. The maximum
input bias current with the inverting input at 2.5 V is –2.0
μ
A.
This can cause an output voltage error that is equal to the
product of the input bias current and the equivalent input
divider source resistance.
The Error Amp Output (Pin 1) is provided for external loop
compensation (Figure 29). The output voltage is offset by two
diodes drops (
≈
1.4 V) and divided by three before it connects
to the inverting input of the Current Sense Comparator. This
guarantees that no drive pulses appear at the Source Output
(Pin 11) when Pin 1 is at its lowest state (VOL). This occurs
when the power supply is operating and the load is removed,
or at the beginning of a soft–start interval. The Error Amp
minimum feedback resistance is limited by the amplifier’s
minimum source current (0.5 mA) and the required output
voltage (VOH) to reach the comparator’s 1.0 V clamp level:
Rf(min)
3.0 (1.0 V)
1.4 V
0.5mA
8800
+
1.0 mA
2.5V
2.5V
Figure 29. Error Amplifier Compensation
Compensation
RFB
Cf
R1
R2
From Power Supply Output
Rf
1
3
Voltage
Feedback
Input
Error
Amplifier
Foldback
Amplifier
2R
R
1.0V
Current Sense
Comparator
Gnd
9
I
Current Sense Comparator and PWM Latch
The MC44602 operates as a current mode controller,
where output switch conduction is initiated by the oscillator
and terminated when the peak inductor current reaches the
threshold level established by the Error Amplifier output (Pin
1). Thus the error signal controls the peak inductor current on
a cycle–by–cycle basis. The Current Sense Comparator
PWM Latch configuration used ensures that only a single
pulse appears at the Source Output during the appropriate
oscillator cycle. The inductor current is converted to a voltage
by inserting the ground referenced sense resistor RS in series
with the emitter of output switch Q1. This voltage is monitored
by the Current Sense Input (Pin 6) and compared to a level
derived from the Error Amp output. The peak inductor current
under normal operating conditions is controlled by the
voltage at Pin 1 where:
lpk
V(Pin1)
1.4V
3 RS
Abnormal operating conditions occur when the power
supply output is overloaded or if output voltage sensing is
lost. Under these conditions, the Current Sense Comparator
threshold will be internally clamped to 1.0 V. Therefore the
maximum peak switch current is:
lpk(max)
1.0 V
RS
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MC44603ADW | RV Series - Econoline Unregulated DC-DC Converters; Input Voltage (Vdc): 3.3V; Output Voltage (Vdc): 15V; Power: 2W; High Isolation 2W Converter; Approved for Medical Applications; EN and UL Safety Certificates; 6kVDC Isolation; Skinny DIP24 Package; Optional Continuous Short Circuit Protected; Fully Encapsulated; Very Low Isolation Capacitance |
| MC44603 | MIXED FREQUENCY MODE GREENLINE PWM CONTROLLER |
| MC44603DW | MIXED FREQUENCY MODE GREENLINE PWM CONTROLLER |
| MC44603P | MIXED FREQUENCY MODE GREENLINE PWM CONTROLLER |
| MC44603AP | RV Series - Econoline Unregulated DC-DC Converters; Input Voltage (Vdc): 3.3V; Output Voltage (Vdc): 24V; Power: 2W; High Isolation 2W Converter; Approved for Medical Applications; EN and UL Safety Certificates; 6kVDC Isolation; Skinny DIP24 Package; Optional Continuous Short Circuit Protected; Fully Encapsulated; Very Low Isolation Capacitance |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MC44603 | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:MIXED FREQUENCY MODE GREENLINE PWM CONTROLLER |
| MC44603A | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:MIXED FREQUENCY MODE GREENLINE PWM CONTROLLER |
| MC44603A_05 | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:Enhanced Mixed Frequency Mode GreenLine TM PWM Controller:Fixed Frequency, Variable Frequency,Standby Mode |
| MC44603ADW | 功能描述:電流型 PWM 控制器 Voltage/Current PWM RoHS:否 制造商:Texas Instruments 開關(guān)頻率:27 KHz 上升時間: 下降時間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| MC44603ADWG | 功能描述:電流型 PWM 控制器 ANA SMPS PWM FREQ CONT RoHS:否 制造商:Texas Instruments 開關(guān)頻率:27 KHz 上升時間: 下降時間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
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