UC1823J [TI]
;
| 型号： | UC1823J |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | 稳压器 开关式稳压器或控制器 电源电路 开关式控制器 |
| 文件： | 总7页 (文件大小：411K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
UC1823
UC2823
UC3823
High Speed PWM Controller
FEATURES
DESCRIPTION
•
Compatible with Voltage or Current-Mode
Topologies
The UC1823 family of PWM control ICs is optimized for high fre-
quency switched mode power supply applications. Particular care
was given to minimizing propagation delays through the compara-
tors and logic circuitry while maximizing bandwidth and slew rate
of the error amplifier. This controller is designed for use in either
current-mode or voltage-mode systems with the capability for input
voltage feed-forward.
•
Practical Operation @ Switching
Frequencies to 1.0MHz
•
•
•
•
50ns Propagation Delay to Output
High Current Totem Pole Output (1.5A peak)
Wide Bandwidth Error Amplifier
Protection circuitry includes a current limit comparator, a TTL com-
patible shutdown port, and a soft start pin which will double as a
maximum duty cycle clamp. The logic is fully latched to provide jit-
ter free operation and prohibit multiple pulses at the output. An un-
der-voltage lockout section with 800mV of hysteresis assures low
start up current. During under-voltage lockout, the output is high im-
pedance. The current limit reference (pin 11) is a DC input voltage to
the current limit comparator. Consult specifications for details.
Fully Latched Logic with Double Pulse
Suppression
•
•
•
•
•
Pulse-by-Pulse Current Limiting
Soft Start/Max. Duty Cycle Control
Under-Voltage Lockout with Hysteresis
Low Start Up Current (1.1mA)
These devices feature a totem pole output designed to source and
sink high peak currents from capacitive loads, such as the gate of
a power MOSFET. The on state is defined as a high level.
Trimmed Bandgap Reference (5.1V ±1%)
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (Pins 15, 13) . . . . . . . . . . . . . . . . . . . . . . . . 30V Oscillator Charging Current (Pin 5) . . . . . . . . . . . . . . . . . . -5mA
Output Current, Source or Sink (Pin14) Power Dissipation at TA = 60 °C . . . . . . . . . . . . . . . . . . . . . 1W
DC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.5A Storage Temperature Range . . . . . . . . . . . . . . -65°C to +150°C
Pulse (0.5µs). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.0A Lead Temperature (Soldering, 10 seconds) . . . . . . . . . . 300°C
Analog Inputs (Pins 1, 2, 7, 8, 9, 11) . . . . . . . . . . . -0.3V to +6V Note: All voltages are with respect to ground, Pin 10.
Currents are positive into the specified terminal.
Consult Packaging Section of Databook for thermal
limitations and considerations of packages.
Clock Output Current (Pin 4) . . . . . . . . . . . . . . . . . . . . . . . -5mA
Error Amplifier Output Current (Pin 3) . . . . . . . . . . . . . . . . 5mA
Soft Start Sink Current (Pin 8) . . . . . . . . . . . . . . . . . . . . . 20mA
BLOCK DIAGRAM
3/97
1
UC1823
UC2823
UC3823
CONNECTION DIAGRAMS
DIL-16, SOIC-16 (TOP VIEW)
J or N, DW Package
PLCC-20, LCC-20 (TOP VIEW)
Q, L Package
PACKAGE PIN FUNCTION
FUNCTION
N/C
PIN
1
Inv.
2
N.I.
3
E/A Out
Clock
N/C
4
5
6
RT
7
CT
8
Ramp
Soft start
N/C
9
10
11
12
13
14
15
16
17
18
19
20
ILIM/S.D.
Ground
ILIM REF
PWR Gnd
N/C
VC
OUT
VCC
VREF 5.1V
ELECTRICAL CHARACTERISTICS: Unless otherwise noted, these specifications apply for RT = 3.65k, CT =
1nF, VCC = 15V, 0°C < TA < +70°C for the UC3823, -25°C < TA < +85°C for
the UC2823, and -55°C < TA < +125°C for the UC1823, TA = TJ.
UC1823
UC2823
UC3823
UNITS
PARAMETER
Reference Section
TEST CONDITIONS
MIN
TYP
MAX
MIN
TYP
MAX
Output Voltage
Line Regulation
TJ = 25°C, lO = 1mA
5.05
5.10
2
5.15
20
5.00
5.10
2
5.20
20
V
10 < VCC < 30V
1 < IO < 10mA
mV
mV
Load Regulation
5
20
5
20
Temperature Stability*
Total Output Variation*
Output Noise Voltage*
Long Term Stability*
Short Circuit Current
Oscillator Section
Initial Accuracy*
TMIN < TA < TMAX
Line, Load, Temp.
10Hz < f < 10kHz
TJ = 125°C, 1000 hrs.
VREF=0V
0.2
0.4
5.20
0.2
0.4 mV/°C
5.00
4.95
5.25
50
5
50
5
µV
25
25
mV
mA
-15
-50
-100
-15
-50
-100
TJ=25°C
360
400
0.2
5
440
2
360
400
0.2
5
440
2
kHz
%
%
kHz
V
Voltage Stability*
Temperature Stability*
Total Variation*
10 < VCC < 30V
TMIN <TA < TMAX
Line, Temp.
340
3.9
460
340
3.9
460
Clock Out High
4.5
2.3
2.8
1.0
1.8
4.5
2.3
2.8
1.0
1.8
Clock Out Low
2.9
3.0
2.9
3.0
V
Ramp Peak*
2.6
0.7
1.6
2.6
0.7
1.6
V
Ramp Valley*
1.25
2.0
1.25
2.0
V
Ramp Valley to Peak*
V
* These parameters are guaranteed by design but not 100% tested in production.
2
UC1823
UC2823
UC3823
ELECTRICAL CHARACTERISTICS: Unless otherwise noted, these specifications apply for RT = 3.65k, CT = 1nF, VCC
= 15V, 0°C < TA < +70°C for the UC3823, -25°C < TA < +85°C for the
UC2823, and -55°C < TA < +125°C for the UC1823, TA = TJ.
UC1823
UC2823
UC3823
TYP
UNITS
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
MIN
MAX
Error Amplifier Section
Input Offset Voltage
Input Bias Current
Input Offset Current
Open Loop Gain
10
3
15
3
mV
µA
0.6
0.1
95
0.6
0.1
95
1
1
µA
1 < VO < 4V
60
75
85
1
60
75
85
1
dB
CMRR
1.5 < VCM < 5.5V
10 < VCC < 30V
VPIN 3 =1V
95
95
dB
PSRR
110
2.5
-1.3
4.7
0.5
5.5
12
110
2.5
-1.3
4.7
0.5
5.5
12
dB
Output Sink Current
Output Source Current
Output High Voltage
Output Low Voltage
Unity Gain Bandwidth*
Slew Rate*
mA
mA
V
VPIN 3 = 4V
-0.5
4.0
0
-0.5
4.0
0
IPIN 3 = −0.5mA
IPIN 3 = 1mA
5.0
1.0
5.0
1.0
V
3
3
MHz
V/µS
6
6
PWM Comparator Section
Pin 7 Bias Current
Duty Cycle Range
Pin 3 Zero D.C. Threshold
Delay to Output*
VPIN 7 = 0V
VPIN 7 = 0V
-1
-5
-1
-5
µA
%
V
0
80
0
85
1.1
1.25
50
1.1
1.25
50
80
20
80
20
ns
Soft-Start Section
Charge Current
V
PIN 8 = 0.5V
3
1
9
3
1
9
µA
Discharge Current
Current Limit/Shutdown Section
Pin 9 Bias Current
Current Limit Offset
VPIN 8 = 1V
mA
0 < VPIN 9 < 4V
VPIN 11 = 1.1V
±10
15
±10
15
µA
mV
V
Current Limit Common Mode
Range (VPIN 11)
1.0
1.25
1.0
1.25
Shutdown Threshold
Delay to Output*
1.25
1.40
50
1.55
80
1.25
1.40
50
1.55
80
V
ns
Output Section
Output Low Level
IOUT = 20mA
IOUT = 200mA
IOUT = −20mA
IOUT = −200mA
VC = 30V
0.25
1.2
0.40
2.2
0.25
1.2
0.40
2.2
V
V
Output High Level
13.0
12.0
13.5
13.0
100
30
13.0
12.0
13.5
13.0
100
30
V
V
Collector Leakage
Rise/Fall Time*
500
60
500
60
µA
ns
CL = 1nF
Under-Voltage Lockout Section
Start Threshold
8.8
0.4
9.2
0.8
9.6
1.2
8.8
0.4
9.2
0.8
9.6
1.2
V
V
UVLO Hysteresis
Supply Current
Start Up Current
ICC
VCC = 8V
1.1
22
2.5
33
1.1
22
2.5
33
mA
mA
VPIN 1, VPIN 7, VPIN 9 =0V, VPIN 2 = 1V
* These parameters are guaranteed by design but not 100% tested in production.
3
UC1823
UC2823
UC3823
UC1823 PRINTED CIRCUIT BOARD LAYOUT
CONSIDERATIONS
High speed circuits demand careful attention to layout
and component placement. To assure proper perform-
ance of the UC1823, follow these rules. 1) Use a ground
plane. 2) Damp or clamp parasitic inductive kick energy
from the gate of driven MOSFET. Don’t allow the output
pins to ring below ground. A series gate resistor or a
shunt 1 Amp Schottky diode at the output pin will serve
this purpose. 3) Bypass VCC, VC, and VREF. Use 0.1µF
monolithic ceramic capacitors with low equivalent series
inductance. Allow less than 1 cm of total lead length for
each capacitor between the bypassed pin and the ground
plane. 4) Treat the timing capacitor, CT, like a bypass ca-
pacitor.
ERROR AMPLIFIER CIRCUIT
Simplified Schematic
Unity Gain Slew Rate
Open Loop Frequency Response
PWM APPLICATIONS
Conventional (Voltage Mode)
Current-Mode
* A small filter may be required to suppress switch
4
UC1823
UC2823
UC3823
OSCILLATOR CIRCUIT
SYNCHRONIZED OPERATION
Two Units in Close Proximity
Generalized Synchronization
5
UC1823
UC2823
UC3823
CONSTANT VOLT-SECOND CLAMP CIRCUIT
The circuit shown here will achieve a constant
volt-second product clamp over varying input
voltages. The ramp generator components, RT and CR
are chosen so that the ramp at Pin 9 crosses the 1V
threshold at the same time the desired maximum
volt-second product is reached. The delay through the
inverter must be such that the ramp capacitor can be
completely discharged during the minimum deadtime.
OUTPUT SECTION
FEED FORWARD TECHNIQUE FOR OFF-LINE VOLTAGE MODE APPLICATION
UNITRODE CORPORATION
7 CONTINENTAL BLVD. • MERRIMACK, NH 03054
TEL. (603) 424-2410 • FAX (603) 424-3460
6
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