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UC1825
UC2825
UC3825
High Speed PWM Controller
FEATURES
•
•
•
•
•
•
•
•
•
•
Compatible with Voltage or Current Mode
Topologies
DESCRIPTION
The UC1825 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 comparators
Practical Operation Switching Frequencies
and logic circuitry while maximizing bandwidth and slew rate of the
to 1MHz
error amplifier. This controller is designed for use in either cur-
50ns Propagation Delay to Output
rent-mode or voltage mode systems with the capability for input volt-
age feed-forward.
High Current Dual Totem Pole Outputs
(1.5A Peak)
Protection circuitry includes a current limit comparator with a 1V
threshold, a TTL compatible shutdown port, and a soft start pin
Wide Bandwidth Error Amplifier
which will double as a maximum duty cycle clamp. The logic is fully
Fully Latched Logic with Double Pulse
latched to provide jitter free operation and prohibit multiple pulses at
Suppression
an output. An under-voltage lockout section with 800mV of hysteresis
assures low start up current. During under-voltage lockout, the out-
Pulse-by-Pulse Current Limiting
puts are high impedance.
Soft Start / Max. Duty Cycle Control
These devices feature totem pole outputs designed to source and
sink high peak currents from capacitive loads, such as the gate of a
Under-Voltage Lockout with Hysteresis
power MOSFET. The on state is designed as a high level.
Low Start Up Current (1.1mA)
BLOCK DIAGRAM
UDG-92030-2
SLUS235A - MARCH 1997 - REVISED MARCH 2004
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Supply Voltage (Pins 13, 15) . . . . . . . . . . . . . . . . . . . . . . . . 30V
Output Current, Source or Sink (Pins 11, 14)
DC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.5A
Pulse (0.5m s) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.0A
Analog Inputs
(Pins 1, 2, 7). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 7V
(Pin 8, 9) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6V
Clock Output Current (Pin 4) . . . . . . . . . . . . . . . . . . . . . . . -5mA
Error Amplifier Output Current (Pin 3) . . . . . . . . . . . . . . . . 5mA
Soft Start Sink Current (Pin 8) . . . . . . . . . . . . . . . . . . . . . 20mA
Oscillator Charging Current (Pin 5) . . . . . . . . . . . . . . . . . . -5mA
Power Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1W
Storage Temperature Range . . . . . . . . . . . . . . -65°C to +150°C
Lead Temperature (Soldering, 10 seconds) . . . . . . . . . . 300°C
CONNECTION DIAGRAMS
DIL-16 (Top View)
J or N Package
UC1825
UC2825
UC3825
SOIC-16 (Top View)
DW Package
PLCC-20 & LCC-20
(Top View)
Q & L Packages
PACKAGE PIN FUNCTION
FUNCTION
PIN
N/C
INV
NI
E/A Out
Clock
N/C
R
T
C
T
Ramp
Soft Start
N/C
ILIM/SD
Gnd
Out A
Pwr Gnd
N/C
V
C
Out B
V
CC
V
REF
5.1V
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
THERMAL RATINGS TABLE
Package
DIL-16J
DIL-16N
PLCC-20
LCC-20
SOIC-16
Q
Q
JA
80-120
90
(1)
43-75(1)
70-80
50-120
(1)
Q
JC
28
(2)
45
34
20
(2)
35
Q
2
UC1825
UC2825
UC3825
ELECTRICAL CHARACTERISTICS:
Unless otherwise stated, these specifications apply for , R
T
= 3.65k, C
T
= 1nF, V
CC
= 15V, -55°C<T
A
<125°C for the UC1825, –40°C<T
A
<85°C for the UC2825, and 0°C<T
A
<70°C for the UC3825, T
A
=T
O.
UC1825
UC2825
MIN
TOP MAX
5.05
5.10
2
5
0.2
50
5
-50
400
0.2
5
5.15
20
20
0.4
5.20
25
-100
440
2
460
4.5
2.3
2.8
1.0
1.8
PARAMETERS
Reference Section
Output Voltage
Line Regulation
Load Regulation
Temperature Stability*
Total Output Variation*
Output Noise Voltage*
Long Term Stability*
Short Circuit Current
Oscillator Section
Initial Accuracy*
Voltage Stability*
Temperature Stability*
Total Variation*
Oscillator Section (cont.)
Clock Out High
Clock Out Low
Ramp Peak*
Ramp Valley*
Ramp Valley to Peak*
Error Amplifier Section
Input Offset Voltage
Input Bias Current
Input Offset Current
Open Loop Gain
CMRR
PSRR
Output Sink Current
Output Source Current
Output High Voltage
Output Low Voltage
Unity Gain Bandwidth*
Slew Rate*
TEST CONDITIONS
UC3825
MIN
5.00
TOP
5.10
2
5
0.2
50
5
-50
400
0.2
5
MAX UNITS
5.20
20
20
0.4
5.25
25
-100
440
2
460
4.5
2.3
2.8
1.0
1.8
V
mV
mV
mV/°C
V
µV
mV
mA
kHz
%
%
kHz
V
V
V
V
V
mV
µA
µA
dB
dB
dB
mA
mA
V
V
MHz
V/µs
T
O
= 25°C, I
O
= 1mA
10V < V
CC
< 30V
1mA < I
O
< 10mA
T
MIN
< T
A
< T
MAX
Line, Load, Temperature
10Hz < f < 10kHz
T
J
= 125°C, 1000hrs.
V
REF
= 0V
T
J
= 2°C
10V < V
CC
< 30V
T
MIN
< T
A
< T
MAX
Line, Temperature
5.00
4.95
-15
360
-15
360
340
3.9
2.6
0.7
1.6
340
3.9
2.9
3.0
1.25
2.0
10
3
1
2.6
0.7
1.6
2.9
3.0
1.25
2.0
15
3
1
1V < V
O
< 4V
1.5V < V
CM
< 5.5V
10V < V
CC
< 30V
V
PIN 3
= 1V
V
PIN 3
= 4V
I
PIN 3
= -0.5mA
I
PIN 3
= 1mA
60
75
85
1
-0.5
4.0
0
3
6
0.6
0.1
95
95
110
2.5
-1.3
4.7
0 .5
5.5
12
5.0
1.0
60
75
85
1
-0.5
4.0
0
3
6
0.6
0.1
95
95
110
2.5
-1.3
4.7
0.5
5.5
12
5.0
1.0
3
UC1825
UC2825
UC3825
ELECTRICAL CHARACTERISTICS:
Unless otherwise stated, these specifications apply for , R
T
= 3.65k, C
T
= 1nF, V
CC
= 15V, -55°C<T
A
<125°C for the UC1825, –40°C<T
A
<85°C for the UC2825, and 0°C<T
A
<70°C for the UC3825, T
A
=T
J.
UC1825
UC2825
MIN
TOP MAX
-1
0
1.1
1.25
50
9
-5
80
80
20
3
1
PARAMETERS
TEST CONDITIONS
UC3825
MIN
TOP
-1
0
1.1
1.25
50
9
MAX UNITS
-5
85
80
20
µA
%
V
ns
µA
mA
µA
V
V
ns
V
V
V
V
µA
ns
V
V
mA
mA
PWM Comparator Section
Pin 7 Bias Current
V
PIN 7
= 0V
Duty Cycle Range
Pin 3 Zero DC Threshold
V
PIN 7
= 0V
Delay to Output*
Soft-Start Section
Charge Current
V
PIN 8
= 0.5V
Discharge Current
V
PIN 8
= 1V
Current Limit / Shutdown Section
Pin 9 Bias Current
0 < V
PIN 9
< 4V
Current Limit Threshold
Shutdown Threshold
Delay to Output
Output Section
Output Low Level
I
OUT
= 20mA
I
OUT
= 200mA
Output High Level
I
OUT
= -20mA
I
OUT
= -200mA
Collector Leakage
V
C
= 30V
Rise/Fall Time*
CL = 1nF
Under-Voltage Lockout Section
Start Threshold
UVLO Hysteresis
Supply Current Section
Start Up Current
V
CC
= 8V
ICC
V
PIN 1
, V
PIN 7
, V
PIN 9
= 0V; V
PIN 2
= 1V
3
1
0.9
1.25
1.0
1.40
50
0.25
1.2
13.5
13.0
100
30
9.2
0.8
1.1
22
15
1.1
1.55
80
0.40
2.2
0.9
1.25
1.0
1.40
50
0.25
1.2
13.5
13.0
10
30
9.2
0.8
1.1
22
10
1.1
1.55
80
0.40
2.2
13.0
12.0
13.0
12.0
500
60
9.6
1.2
2.5
33
8.8
0.4
500
60
9.6
1.2
2.5
33
8.8
0.4
4
嵌入式系统
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