TI UC3838A

UC1838A
UC2838A
UC3838A
Magnetic Amplifier Controller
FEATURES
DESCRIPTION
• Independent 1% Reference
The UC1838A family of magnetic amplifier controllers contains the circuitry to generate and amplify a low-level analog error signal along with a high voltage-compliant current source. This source will provide the reset current necessary
to enable a magnetic amplifier to regulate and control a power supply output in the
range of 2A to 20A.
• Two Uncommitted, Identical
Operational Amplifiers
• 100mA Reset Current Source
with –120V Capability
• 5V to 40V Analog Operation
• 5W DIL Package
By controlling the reset current to a magnetic amplifier, this device will define the
amount of volt-seconds the magnetic amplifier will block before switching to the
conducting state. Magnetic amplifiers are ideal for post-regulators for multiple-output power supplies where each output can be independently controlled with
efficiencies up to 99%. With a square or pulse-width-modulated input voltage, a
magnetic amplifier will block a portion of this input waveform, allowing just enough
to pass to provide a regulated output. With the UC1838A, only the magnetic amplifier coil, three diodes, and an output L-C filter are necessary to implement a complete closed-loop regulator.
The UC1838A contains a precision 2.5V reference, two uncommitted high-gain op
amps and a high-gain PNP-equivalent current source which can deliver up to
100mA of magnetic amplifier reset current and with –120 volt capability.
These devices are available in a plastic “bat-wing” DIP for operation over a –20°C
to +85°C temperature range and, with reduced power, in a hermetically sealed
cerdip for –55°C to +125°C operation. Surface mount versions are also available.
This improved “A” version replaced the non “A” version formerly introduced.
BLOCK DIAGRAM
VCC
10
VREF
9
2.5V
REFERENCE
11
INV. IN
6
3.5V
E/A
N.I. IN
7
E/A OUT
8
INV. IN
3
5k
20
14 RESET
C/L
N.I. IN
1k
VM
15 DR 1
2
16 DR 2
C/L OUT
1
4
5
12
13
GND GND GND GND
04/99
UDG-97174
UC1838A
UC2838A
UC3838A
CONNECTION DIAGRAMS
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40V
Magnetic Amp. Source Voltage, VM . . . . . . . . . . . . . . . . . . . . . . . . 40V
Reset Output Voltage, VR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –120V
Total Current Source Voltage, VM - VR . . . . . . . . . . . . . . . . . . –140V
Amplifier Input Range . . . . . . . . . . . . . . . . . . . . . . –0.3V to VCC
Reset Input Current, IDR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –10mA
Power Dissipation at TA = 25°C
Q, N, DP Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2W
J, L Package. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1W
Power Dissipation at T (leads/case) = 25°C
Q, N, DP Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5W
J, L Package. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2W
Operating Temperature Range . . . . . . . . . . . . –55°C to +125°C
Storage Temperature Range . . . . . . . . . . . . . –65°C to +150°C
Lead Temperature (Soldering, 10 sec) . . . . . . . . . . . . . . 300°C
DIL-16, SOIC-16 (TOP VIEW)
J or N Package, DP Package
Note: All voltages are with respect to ground pins. All currents
are positive into the specified terminal. Consult Packaging
section of Databook for thermal limitations and considerations
of package.
TEMPERATURE RANGE
–55°C to +125°C
–20°C to +85°C
0°C to +70°C
1
16
DR 2
C/L N.I. In
2
15
DR 1
C/L INV. In
3
14
Reset
Gnd
4
13
Gnd
Gnd
5
12
Gnd
E/A Inv. In
6
11
VM
E/A N.I. In
7
10
VCC
E/A Out
8
9
VREF
Note: All four ground pins must be connected to a common
ground
ORDERING INFORMATION
UC1838AJ
UC1838AL
UC2838ADP
UC2838AN
UC2838AQ
UC3838ADP
UC3838AN
UC3838AQ
C/L Out
PACKAGE
Ceramic Dip
CLCC
Power SOIC
Plastic Dip
PLCC
Power SOIC
Plastic Dip
PLCC
PLCC-20, LCC-20 (TOP VIEW)
Q, L Packages
N/C
C/L Out
C/L N.I. In
DR2
DR1
3
1
20 19
C/L Inv. In
4
18
Reset
GND
5
17
N/C
N/C
6
16
N/C
N/C
7
15
GND
E/A Inv. In
8
14
VM
9
E/A N.I. In
E/A Out
2
2
10 11 12 13
VCC
VREF
N/C
UC1838A
UC2838A
UC3838A
ELECTRICAL CHARACTERISTICS: Unless otherwise stated, these specifications apply for TA = –55°C to +125°C for the
UC1838A, –20°C to +85°C for the UC2838A, and 0°C to +70°C for the UC3838A, VCC = 20V, VM = 5V, TA = TJ.
UC1838A / UC2838A
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
4
8
2.47
2.5
2.53
UC3838A
UNITS
MIN
TYP
MAX
4
8
mA
2.45
2.5
2.55
V
Reference Section
Supply Current
VCC = VM = 40V
Reference Output
TA = 25°C
Line Regulation
VCC = 5 to 30V
1
5
1
10
mV
Load Regulation
IO = 0 to –2mA
5
20
5
20
mV
Short Circuit Current
VREF = 0V
–30
–60
–30
–60
mA
Temperature Stability*
Over Operating Temp. Range
15
25
10
25
mV
10
mV
–1
–1
µA
100
100
nA
Amplifier Section (Each Amplifier)
Offset Voltage
VCM = 2.5V
Input Bias Current
VIN = 0V
5
Input Offset Current
Minimum Output Swing
Output Sink Current
0.4
VO = 5V
1
18
0.4
10
30
1
–20
18
V
10
30
mA
–20
mA
Output Source Current
VO = 0V
–1
–10
–1
–10
AVOL
VO = 1 to 11V
100
120
100
120
dB
CMRR
VIN = 1 to 11V
70
80
70
80
dB
PSRR
VCC = 10 to 20V
70
100
70
100
dB
0.6
0.8
0.6
0.8
MHz
Gain Bandwidth*
Reset Drive Section
Input Leakage
VDR = 40V
Output Leakage
VR = –120V
Input Current
IR = –50mA
Maximum Reset Current
IDR = –3mA
Transconductance
IR = –10 to –50mA
+12V, 4A output with switching frequency = 50 kHz.
3
10
µA
–100
µA
–1
–2
–1
–2
mA
–100
–120
–200
–100
–120
–200
mA
.03
.042
.055
.03
.042
.055
A/V
* These parameters are guaranteed by design but not 100% tested in production.
TYPICAL APPLICATION
10
–100
UC1838A
UC2838A
UC3838A
APPLICATION INFORMATION
Figure 1. Amplifier open loop response.
Figure 4. Reset driver response.
Figure 2. Reset driver-input current.
Figure 5. Reset driver-input voltage.
Figure 3. Reset driver-output impedance.
Figure 6. Reference temperature coefficient.
UNITRODE CORPORATION
7 CONTINENTAL BLVD. • MERRIMACK, NH 03054
TEL. (603) 424-2410 • FAX (603) 424-3460
4
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