鈥?/div>
5W DIL Package
DESCRIPTION
The UC1838A family of magnetic amplifier controllers contains the circuitry to gen-
erate and amplify a low-level analog error signal along with a high volt-
age-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.
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 multi-
ple-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 ampli-
fier coil, three diodes, and an output L-C filter are necessary to implement a com-
plete 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 鈥?20 volt capability.
These devices are available in a plastic 鈥渂at-wing鈥?DIP for operation over a 鈥?0擄C
to +85擄C temperature range and, with reduced power, in a hermetically sealed
cerdip for 鈥?5擄C to +125擄C operation. Surface mount versions are also available.
This improved 鈥淎鈥?version replaced the non 鈥淎鈥?version formerly introduced.
BLOCK DIAGRAM
VCC
VREF
10
9
2.5V
REFERENCE
11
VM
INV. IN
6
E/A
3.5V
5k
1k
20
N.I. IN
E/A OUT
INV. IN
7
8
3
C/L
14 RESET
15 DR 1
16 DR 2
N.I. IN
2
C/L OUT
1
4
5
12
13
UDG-97174
GND GND GND GND
04/99
1
2
3
4
5
