AP3845N8LA [ANACHIP]
High Performance Current Mode PWM Controller; 高性能电流模式PWM控制器型号: | AP3845N8LA |
厂家: | ANACHIP CORP |
描述: | High Performance Current Mode PWM Controller |
文件: | 总8页 (文件大小:216K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
AP3842/3/4/5
High Performance Current Mode PWM Controller
Features
General Description
• Optimized for Off-Line and DC to DC Converters
• Low Start-Up Current (≦0.5mA)
The AP3842/3/4/5 family of control ICs provides the
necessary features to implement off-line or DC to
DC fixed frequency current mode control schemes
with a minimal external parts count. Internally
implemented circuits include under voltage lockout
featuring start-up current less than 0.5 mA, a
precision reference trimmed for accuracy at the
error amp input, logic to insure latched operation, a
PWM comparator which also provides current limit
control, and a totem pole output stage designed to
source or sink high peak current. The output stage,
suitable for driving N-Channel MOSFETs, is low in
the off-state.
• Automatic Feed Forward Compensation
• Pulse-by-Pulse Current Limiting
• Enhanced Load Response Characteristics
• Under-Voltage Lockout (UVLO) with Hysteresis
• Double Pulse Suppression
• High Current Totem Pole Output
• Internally Trimmed Bandgap Reference
• Current Mode Operation to 500KHZ
• Low Ro Error Amplifier
Pin Connections
PDIP-8L, SOP-8L
Top View
Differences between members of this family are the
under-voltage lockout thresholds and maximum
duty cycle ranges. The AP3842 and AP3844 have
UVLO thresholds of 16V(on) and 10V(off), ideally
suited for off-line applications. The corresponding
thresholds for the AP3843 and AP3845 are 8.5V
and 7.6V. The AP3842 and AP3843 can operate to
duty cycles approaching 100%. A range of the zero
to < 50% is obtained by the AP3844 and AP3845
by the addition of an internal toggle flip flop which
blanks the output off every other clock cycle.
COMP.
VFB
VREF
VI
1
2
3
4
8
7
6
5
ISENSE
RT/CT
OUTPUT
GROUND
Ordering Information
AP 384X X X X
Part No.
Package
Packing
Lead Free
2:3842
3:3843
4:3844
5:3845
S8:SOP-8L
N8:PDIP-8L
Blank : Normal
Blank: Tube
L : Lead Free Package
A : Taping
This datasheet contains new product information. Anachip Corp. reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of
this product. No rights under any patent accompany the sale of the product.
Rev.1.0 Oct.11, 2004
1/8
AP3842/3/4/5
High Performance Current Mode PWM Controller
Block Diagram ( toggle flip flop used only in AP3844 and AP3845 )
7
Vi
36V
UVLO
8
6
VREF
5V
16V
5V 50mA
S/R
5
REF
GROUND
RT/CT
INTERNAL
BIAS
2.50V
VREF GOOD
LOGIC
OUTPUT
4
2
OSC.
ERROR AMP.
T
S
2R
VFB
PWM
LATCH
R
R
1
3
1V
CURRENT
SENSE
COMP
CURRENT
SENSE
AP384X
COMPARATOR
Absolute Maximum Ratings
Symbol
Parameter
Value
Unit
Vi
Vi
Io
Supply Voltage (low impedance source)
36
Self Limiting
±0.7
V
Supply Voltage (li < 30mA)
Output Current
A
µJ
V
Eo
Output Energy (capacitive load)
Analog Inputs (pins2,3)
5
-0.3 to 5.5
10
Error Amplifier Output Sink Current
Power Dissipation at Tamb ≦500C (PDIP8)
Power Dissipation at Tamb ≦250C (SOP8)
Storage Temperature Range
mA
W
Ptot
Ptot
Tstg
TL
1.25
800
mW
oC
oC
-65 to 150
260
Lead Temperature (soldering 10s)
*Notes: 1. All voltages are with respect to pin 5, all currents are positive into the specified terminal.
Electrical Characteristics
(Unless otherwise stated, these specifications apply for 0≦Tamb≦70oC for AP384X ; Vi = 15V(note 5); RT = 10KΩ;CT = 3.3nF)
AP384X
Symbol
Parameter
Test Conditions
Unit
Min. Typ. Max.
REFERENCE SECTION
VREF
∆VREF
Output Voltage
Tj = 250C I0=1mA
12V≦Vi≦25V
4.90 5.00 5.10
V
mV
mV
Line Regulation
Load Regulation
2
3
20
25
∆VREF
1mA≦Io≦20mA
∆VREF/∆T
Temperature Stability
Total Output Variation
(Notes 2)
0.2 0.4 mV/0C
Line, Load, Temperature (Notes 2) 4.82
10Hz≦f≦10KHz Tj=250C (Notes
2)
5.18
V
eN
Output Noise Voltage
50
5
µV
mV
Long Term Stability
Output Short Circuit current
Tamb=1250C, 1000Hrs (Notes 2)
25
ISC
-85 -120 mA
Anachip Corp.
www.anachip.com.tw
Rev.1.0 Oct.11, 2004
2/8
AP3842/3/4/5
High Performance Current Mode PWM Controller
Electrical Characteristics(Continued)
(Unless otherwise stated, these specifications apply for 0≦Tamb≦70oC for AP384X ; Vi = 15V(note 5); RT = 10KΩ;CT = 3.3nF)
AP384X
Symbol
Parameter
Test Conditions
Unit
Min. Typ. Max.
OSCILLATOR SECTION
fs
Oscillator Frequency
Tj=250C (Notes 6, 7)
12V≦Vi≦25V
MIN≦Tamb≦TMAX (Notes 2)
VPIN4 Peak to Peak
Tj=250C VPIN4=2V
49
52
0.2
0.5
1.6
55
1
KHz
%
Voltage Stability
Temperature Stability
Amplitude
T
%
V4
V
Discharge Current
7.8 8.3 8.8
mA
ERROR AMP SECTION
V2
Ib
Feedback Input Voltage
VPIN1=2.5V
VFB=5V
2.42 2.50 2.58
V
µA
Input Bias Current
AVOL
-0.1
90
1
-2
0V≦V0≦4V
65
0.7
dB
B
Unity Gain Bandwidth
Supply Voltage Rejection
Ratio
Tj=25oC
MHz
SVRR
12V≦Vi≦25V
60
2
70
6
dB
IO
IO
Output Sink Current
Output Source Current
VOUT High
VPIN2=2.7V VPIN1=1.1V
VPIN2=2.3V VPIN1=5V
VPIN2=2.3V; RL=15KΩ to ground
VPIN2=2.7V; RL=15KΩ to pin 8
mA
mA
V
-0.5 -0.8
5
7
VOUT Low
0.8 1.1
V
CURRENT SENSE SECTION
Gv
V3
Gain
(Notes3&Notes4)
VPIN1=5V (Notes3)
2.85
0.9
3
1
3.15 V/V
Maximum Input Signal
Supply Voltage Rejection
Ratio
1.1
V
SVRR
Ib
12≦Vi≦25V (Notes3)
70
-2
dB
Input Bias Current
Delay to Output
-10
µA
ns
150 300
OUTPUT SECTION
ISINK= 20mA
ISINK= 200mA
0.1 0.4
1.6 2.2
V
V
VOL
Output Low Level
ISOURCE= 20mA
13 13.5
12 13.5
V
VOH
Output High Level
ISOURCE= 200mA
V
Tr
Tf
VOLS
Rise Time
Fall Time
UVLO Saturation
Tj=250C CL=1nF (Notes2)
Tj=250C CL=1nF (Notes2)
Vcc = 6V ; Isink = 1mA
50 150
50 150
0.1 1.1
ns
ns
V
UNDER-VOLTAGE LOCKOUT SECTION
3842/4
3843/5
3842/4
3843/5
14.5 16 17.5
V
V
V
V
Start Threshold
7.8 8.4
9
Min Operating Voltage After
Turn-on
8.5
10 11.5
7.0 7.6 8.2
PWM SECTION
3842/3
3844/5
94
47
96
48
%
%
%
Maximum Duty Cycle
50
0
Minimum Duty Cycle
TOTAL STANDBY CURRENT
Vi=14V,3842/4 ;
Vi=6.5V 3843/5
VPIN2=VPIN3=0V
Ii=25mA
Ist
Start-up Current
0.3 0.5
mA
Ii
Viz
Operating Supply Current
Zener Voltage
12
36
17
mA
V
30
Anachip Corp.
www.anachip.com.tw
Rev.1.0 Oct.11, 2004
3/8
AP3842/3/4/5
High Performance Current Mode PWM Controller
Notes:2.These parameters, although guaranteed, are not 100% tested in production.
3.Parameter measured at trip point of latch with VPIN2=0.
4.Gain defined as:
∆VPIN1
; 0≦VPIN3≦0.8V
A=
∆VPIN3
5.Adjust Vi above the start threshold before setting at 15V.
6.Output frequency equals oscillator frequency for the AP3842 and AP3843.
7.Output frequency is one and half oscillator frequency for the AP3844 and AP3845.
Figure 1 : Error Amp Configuration.
2.5V
0.8 mA
VFB
Zf
2
COMP
1
Zf
Error amp can source or sink up to 0.5mA
Figure 2 : Under Voltage Lockout.
I
CC
ON/OFF COMMAND
TO REST OF IC
V
7
i
AP3842 AP3843
<17 mA
<1 mA
AP3844 AP3845
V
16V
10V
8.4V
7.6V
ON
V
V
OFF
CC
V
V
OFF ON
During Under-Voltage Lockout, the output driver is biased to sink minor amounts of current. Pin 6 should be
shunted to ground with a bleeder resistor to prevent activating the power switch with extraneous leakage
currents.
Figure 3 : Current Sense Circuit.
ERROR
2R
AMP
I
S
COMP
R
1V
CURRENT
SENSE
1
COMPARATOR
R
CURRENT
SENSE
3
C
Rs
GND
5
Anachip Corp.
www.anachip.com.tw
Rev.1.0 Oct.11, 2004
4/8
AP3842/3/4/5
High Performance Current Mode PWM Controller
Peak current(is) is determined by the formula
1.0V
IS max ≈
RS
A small RC filter may be required to suppress switch transients.
Figure 4.
8
VREF
RT
4
RT/CT
CT
5
GROUND
1.72
RTCT
for RT > 5KΩ f=
Figure 5 : Open Loop Test Circuit.
V
REF
R
T
A
Vi
4.7K
2N2222
V
1
2
3
4
8
7
6
5
COMP.
REF
100K
0.1
uF
V
i
V
ERROR AMP.
ADJUST
FB
TW
1K
0.1
uF
AP3842
1K
I
5K
SENSE
ADJUST
I
OUTPUT
GROUND
OUTPUT
SENSE
4.7K
R
C
T/
T
GROUND
C
T
High peak currents associated with capacitive loads necessitate careful grounding techniques. Timing and
bypass apacitors should be connected close to pin 5 in a single point ground. The transistor and 5 KΩ
potentiometer are used to sample the oscillator waveform and apply an adjustable ramp to pin 3.
Figure 6 : Shutdown Techniques.
1K
V
I
B
3
REF
1
COMP
330K
SENSE
500K
SHUTDOWN
SHUTDOWN
TO CURRENT
SENSE RESISTOR
Anachip Corp.
www.anachip.com.tw
Rev.1.0 Oct.11, 2004
5/8
AP3842/3/4/5
High Performance Current Mode PWM Controller
Shutdown of the AP3842 can be accomplished in two ways; either raise pin 3 above 1V or pull pin 1 below a
voltage two diode drops above ground. Either one of them causes the output of the PWM comparator to be
high (refer to block diagram). The PWM latch is reset dominant so that the output will remain low until the
next clock cycle after the shutdown condition at pins 1 and/or 3 is removed. In one example, an externally
latched shutdown may be accomplished by adding an SCR that will be reset by cycling Vi below the lower
UVLO threshold. At this point the reference turns off, allowing the SCR to reset.
Figure 7 : Slope Compensation.
Uref
8
4
0.1uF
RT
RT/CT
CT
R1
C
Isense
R2
3
Isense
AP3842/3
Rsense
A fraction of the oscillator ramp can be resistively summed with the current sense signal to provide slope
compensation for converters requiring duty cycles over 50%. Note that capacitor, C, forms a filter with R2 to
suppress the leading edge switch spikes.
Anachip Corp.
www.anachip.com.tw
Rev.1.0 Oct.11, 2004
6/8
AP3842/3/4/5
High Performance Current Mode PWM Controller
Package Diagrams
(1) PDIP-8L (Plastic Dual-in-line Package)
D
E-PIN O0.118 inch
E
(4X)
15
PIN #1 INDENT O0.025 DEEP 0.006-0.008 inch
C
7
(4X)
eB
B
B1
e
S
B2
Dimensions in millimeters
Dimensions in inches
Symbol
Min.
-
Nom.
-
Max.
5.33
-
Min.
Nom.
-
Max.
A
A1
A2
B
-
0.210
-
0.38
3.1
-
0.015
0.122
0.014
0.055
0.032
0.008
0.355
0.300
0.242
-
-
3.30
0.46
1.52
0.99
0.25
9.27
7.94
6.35
2.54
3.3
3.5
0.130
0.018
0.060
0.039
0.010
0.365
0.313
0.250
0.100
0.130
0.350
0.033
0.138
0.022
0.065
0.045
0.014
0.375
0.325
0.258
-
0.36
1.4
0.56
1.65
1.14
0.36
9.53
8.26
6.55
-
B1
B2
C
0.81
0.20
9.02
7.62
6.15
-
2.92
8.38
0.71
D
E
E1
e
L
3.81
9.40
0.97
0.115
0.330
0.028
0.150
0.370
0.038
eB
S
8.89
0.84
Anachip Corp.
www.anachip.com.tw
Rev.1.0 Oct.11, 2004
7/8
AP3842/3/4/5
High Performance Current Mode PWM Controller
(2) SOP-8L (JEDEC Small Outline Package)
L
VIEW "A"
D
0.015x45
7 (4X)
7 (4X)
e
B
VIEW "A"
y
Dimensions In Millimeters
Dimensions In Inches
Symbol
Min.
1.40
0.10
1.30
0.33
0.19
4.80
3.70
-
Nom.
1.60
-
Max.
1.75
0.25
1.50
0.51
0.25
5.30
4.10
-
6.20
1.27
0.10
8O
Min.
Nom.
0.063
-
Max.
A
A1
A2
B
0.055
0.040
0.051
0.013
0.0075
0.189
0.146
-
0.069
0.100
0.059
0.020
0.010
0.209
0.161
-
0.244
0.050
0.004
8O
1.45
0.41
0.20
5.05
3.90
1.27
5.99
0.71
-
0.057
0.016
0.008
0.199
0.154
0.050
0.236
0.028
-
C
D
E
e
H
L
5.79
0.38
-
0.228
0.015
-
y
0O
-
0O
-
θ
Marking Information
Logo
2,3,4,5
Blank: normal
AP384XB
Part No.
L: Lead Free Package
YYWW X X
ID code: internal
Xth Week : 01~52
Year : "01"=2001
"02"=2002
Anachip Corp.
www.anachip.com.tw
Rev.1.0 Oct.11, 2004
8/8
相关型号:
AP3845S8LA
Switching Regulator, Current-mode, 0.7A, 500kHz Switching Freq-Max, PDSO8, LEAD FREE, SOP-8
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