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UC2845A の電気的特性と機能

UC2845AのメーカーはST Microelectronicsです、この部品の機能は「(UC2842A - UC2845A) HIGH PERFORMANCE CURRENT MODE PWM CONTROLLER」です。


製品の詳細 ( Datasheet PDF )

部品番号 UC2845A
部品説明 (UC2842A - UC2845A) HIGH PERFORMANCE CURRENT MODE PWM CONTROLLER
メーカ ST Microelectronics
ロゴ ST Microelectronics ロゴ 




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UC2845A Datasheet, UC2845A PDF,ピン配置, 機能
UC284XA
UC384XA
HIGH PERFORMANCE CURRENT MODE PWM CONTROLLER
NOT FOR NEW DESIGN
1 FEATURES
Figure 1. Package
TRIMMED OSCILLATOR DISCHARGE
CURRENT
CURRENT MODE OPERATION TO 500kHz
AUTOMATIC FEED FORWARD
COMPENSATION
DIP-8
SO-8
LATCHING PWM FOR CYCLE-BY-CYCLE
CURRENT LIMITING
Table 1. Order Codes
INTERNALLY TRIMMED REFERENCE WITH
Part Number
Package
UNDERVOLTAGE LOCKOUT
HIGH CURRENT TOTEM POLE OUTPUT
t(s)UNDERVOLTAGE LOCKOUT WITH
HYSTERESIS
cLOW START-UP CURRENT (< 0.5mA)
uDOUBLE PULSE SUPPRESSION
rod2 DESCRIPTION
PThe UC384xA family of control ICs provides the
necessary features to implement off-line or DC to
teDC fixed frequency current mode control schemes
lewith a minimal external parts count. Internally im-
oplemented circuits include a trimmed oscillator for
sprecise DUTY CYCLE CONTROL under voltage
blockout featuring start-up current less than 0.5mA,
Oa precision reference trimmed for accuracy at the
-error amp input, logic to insure latched operation,
)a PWM comparator which also provides current
t(slimit control, and a totem pole output stage de-
csigned to source or sink high peak current. The
uoutput stage, suitable for driving N-Channel MOS-
dFETs, is low in the off-state.
UC2842AD1; UC3842AD1;
UC2843AD1; UC3843AD1;
UC2844AD1; UC3844AD1;
UC2845AD1; UC3845AD1
UC2842AN; UC3842AN;
UC2843AN; UC3843AN;
UC2844AN; UC3844AN;
UC2845AN; UC3845AN
SO-8
DIP-8
Differences between members of this family are
the under-voltage lockout thresholds and maxi-
mum duty cycle ranges. The UC3842A and
UC3844A have UVLO thresholds of 16V (on) and
10V (off), ideally suited off-line applications The
corresponding thresholds for the UC3843A and
UC3845A are 8.5 V and 7.9V. The UC3842A and
UC3843A can operate to duty cycles approaching
100%. A range of the zero to < 50 % is obtained by
the UC3844A and UC3845A by the addition of an
internal toggle flip flop which blanks the output off
every other clock cycle.
ProFigure 2. Block Diagram (toggle flip flop used only in UC3844A and UC3845A)
te 7
Vi
le 5
Obso GROUND
34V
UVLO
2.50V
S/R
5V
REF
VREF GOOD
INTERNAL
BIAS
8 VREF
5V 50mA
LOGIC
6
OUTPUT
4
RT/CT
OSC
T
VFB
COMP
CURRENT
SENSE
2
1
3
ERROR AMP.
+
-
2R
R
S
R
1V
CURRENT
SENSE
COMPARATOR
PWM
LATCH
D95IN331
May 2004
REV. 5
1/16

1 Page





UC2845A pdf, ピン配列
UC384XA - UC284XA
Table 4. Thermal Data
Symbol
Rth j-amb
Parameter
Thermal Resistance Junction-ambient
Max.
DIP-8
100
SO-8
150
Unit
°C/W
Table 5. Electrical Characteristcs
( [note 1] Unless otherwise stated, these specifications apply for -25 < Tamb < 85°C for UC284XA;
0 < Tamb < 70°C for UC384XA; Vi = 15V (note 5); RT = 10K; CT = 3.3nF)
Symbol
Parameter
Test Condition
UC284XA
UC384XA
Unit
Min. Typ. Max. Min. Typ. Max.
REFERENCE SECTION
VREF Output Voltage
Tj = 25°C Io= 1mA
4.95 5.00 5.05 4.90 5.00 5.10 V
VREF Line Regulation
12V Vi 25V
2 20
2 20 mV
VREF Load Regulation
1 Io 20mA
3 25
3 25 mV
VREF/T Temperature Stability
(Note 2)
Total Output Variation
Line, Load, Temperature
t(s)eN Output Noise Voltage
10Hz f 10KHz
Tj = 25°C (note 2)
ducLong Term Stability
Tamb = 125°C, 1000Hrs
(note 2)
roISC Output Short Circuit
POSCILLATOR SECTION
tefOSC Frequency
Tj = 25°C
lefOSC/V Frequency Change with Volt. VCC = 12V to 25V
oVREF/T Frequency Change with Temp. TA = Tlow to Thigh
bsVOSC Oscillator Voltage Swing (peak to peak)
OIdischg Discharge Current (VOSC =2V) TJ = 25°C
-ERROR AMP SECTION
)V2 Input Voltage
VPIN1 = 2.5V
t(sIb Input Bias Current
VFB = 5V
cAVOL
2V Vo 4V
duBW Unity Gain Bandwidth
TJ = 25°C
roPSRR Power Supply Rejec. Ratio 12V Vi 25V
te PIo Output Sink Current
VPIN2 = 2.7V
VPIN1= 1.1V
leIo Output Source Current
VPIN2 = 2.3V VPIN1 = 5V
soVOUT High
VPIN2 = 2.3V;RL = 15Kto
Ground
Ob VOUT Low
VPIN2 = 2.7V;RL = 15Kto
4.9
-30
47
7.8
2.45
65
0.7
60
2
-0.5
5
0.2
50
5
-100
52
0.2
5
1.6
8.3
2.50
-0.1
90
1
70
12
-1
6.2
0.8
5.1
25
-180
57
1
8.8
2.55
-1
1.1
4.82
-30
47
7.8
2.42
65
0.7
60
2
-0.5
5
0.2
50
5
-100
52
0.2
5
1.6
8.3
2.50
-0.1
90
1
70
12
-1
6.2
0.8
mV/°C
5.18 V
µV
25 mV
-180 mA
57 KHz
1%
–%
–V
8.8 mA
2.58
-2
V
µA
dB
MHz
dB
mA
mA
V
1.1 V
Pin 8
CURRENT SENSE SECTION
GV Gain
(note 3 & 4)
2.85 3 3.15 2.85 3 3.15 V/V
V3 Maximum Input Signal
VPIN1 = 5V (note 3)
0.9 1 1.1 0.9 1 1.1 V
SVR Supply Voltage Rejection 12 Vi 25V (note 3)
70
70 dB
Ib Input Bias Current
-2 -10
-2 -10 µA
Delay to Output
150 300
150 300 ns
3/16


3Pages


UC2845A 電子部品, 半導体
UC384XA - UC284XA
Figure 9. Current Sense Input Threshold vs.
Error Amp Output Voltage.
Figure 12. Output Saturation Voltage vs. Load
Current.
Vth
(V)
Vi=15V
1.0
TA=25˚C
0.8
TA=125˚C
0.6
D95IN338
Vsat
D95IN341
(V)
Vi
Source Saturation
(Load to Ground)
-1 TA=25˚C
TA=-40˚C
-2
Vi=15V
80µs Pulsed Load 120Hz Rate
3
0.4
TA=-40˚C
0.2
0.0
0 2 4 6 VO(V)
2 TA=-40˚C
TA=25˚C
1
Sink Saturation
GND
(Load to Vi)
0
0 200 400 600 IO(mA)
Figure 10. Reference Voltage Change vs.
)Source Current..
t(sD95IN339
60
cVi=15V
u50
rod40 TA=-40˚C
PTA=125˚C
te30
le20
bso10
- O0
)0 20 40 60 80 100 Iref(mA)
t(sFigure 11. Reference Short Circuit Current vs.
cTemperature..
duISC
ro(mA)
P100
D95IN340
Vi=15V
RL0.1
te90
ole80
Obs70
Figure 13. Supply Current vs. Supply Voltage.
Ii
(mA)
20
D95IN342
15
10
RT=10K
CT=3.3nF
VFB=0V
ISense=0V
5 TA=25˚C
0
0
10 20 30 Vi(V)
60
50
-55 -25 0 25 50 75 100 TA(˚C)
6/16

6 Page



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共有リンク

Link :


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HIGH PERFORMANCE CURRENT MODE PWM CONTROLLERS

Unisonic Technologies
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UC2845A

(UC2842A - UC2845A) HIGH PERFORMANCE CURRENT MODE PWM CONTROLLER

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ST Microelectronics


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