Programmable One Shot Timer鈥?/div>
Down to 100ns
Precision 5V Reference
Dual 2A Peak Totem Pole Outputs
Programmable Output Sequence
Programmable Under Voltage Lockout
Very Low Start Up Current
Programmable Fault Management &
Restart Delay
Uncommitted Comparator
DESCRIPTION
The UC1860 family of control ICs is a versatile system for resonant mode
power supply control. This device easily implements frequency modulated
fixed-on-time control schemes as well as a number of other power supply
control schemes with its various dedicated and programmable features.
The UC1860 includes a precision voltage reference, a wide-bandwidth er-
ror amplifier, a variable frequency oscillator operable to beyond 3MHz, an
oscillator-triggered one-shot, dual high-current totem-pole output drivers,
and a programmable toggle flip-flop. The output mode is easily pro-
grammed for various sequences such as A, off, B, off; A & B, off; or A, B,
off. The error amplifier contains precision output clamps that allow pro-
gramming of minimum and maximum frequency.
The device also contains an uncommitted comparator, a fast comparator
for fault sensing, programmable soft start circuitry, and a programmable
restart delay. Hic-up style response to faults is easily achieved. In addi-
tion, the UC1860 contains programmable under voltage lockout circuitry
that forces the output stages low and minimizes supply current during
start-up conditions.
Comparator Output Voltage (pin 15) . . . . . . . . . . . . . . . . . . 15V
Soft Start or Restart Delay Sink Current (pins 22 & 23) . . . 5mA
Power Dissipation at T
A
= 50擄C (DIP) . . . . . . . . . . . . . . . 1.25W
Power Dissipation at T
A
= 50擄C (PLCC) . . . . . . . . . . . . . . . . 1W
Lead Temperature (Soldering, 10 seconds) . . . . . . . . . . . 300擄C
Note: All voltages are with respect to signal ground and all
currents are positive into the specified terminal.
Pin numbers refer to the DIP.
Refer to Packaging Section of Databook for thermal
limitations and considerations of packages.
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (pin 19) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20V
Output Current, Source or Sink (pins 17 & 20)
DC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.8A
Pulse (0.5碌s) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.0A
Power Ground Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . .
鹵0.2V
Inputs (pins 1, 2, 3, 4, 8, 9, 11, 12,
13, 14, 21, 22, 23 & 24) . . . . . . . . . . . . . . . . . . . . . . -0.4 to 6V
Error Amp Output Current, Source or Sink (pin 5) . . . . . . . . 2mA
I
VFO
Current (pin 7). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2mA
Comparator Output Current (pin 15) . . . . . . . . . . . . . . . . . . 5mA
BLOCK DIAGRAM
10/93
1
2
3
4
5
6
7
8
9
