UCC284-5/-12/-ADJ
UCC384-5/-12/-ADJ
Low Dropout 0.5A Negative Linear Regulator
BLOCK DIAGRAM
FEATURES
• Precision Negative Series
Pass Voltage Regulation
(+)
4
GND
• 0.2V Drop Out at 0.5A
1µA
R1
0
R2
DISCHARGE
• Wide Input voltage Range
–3.2V to –15V
UCC384-ADJ
UCC384-5
OPEN
+
–2.2V
SHUTDOWN
375K 125K
375K 43.6K
–
–0.6V
1.25V
R2
50k
UCC384-12
• Low Quiescent Current
+
–
Irrespective of Load
–1.6V
–2.6V
TON
TOFF
Q
Q
S
R
SD/CT
8
• Simple Logic Shutdown
Interfacing
VPUMP
+
–
R1
+
• –5V, –12V and Adjustable
Output
GM
–
40µA
CHARGE
1
VOUTS
• 2.5% Duty Cycle Short Circuit
Protection
OVERCURRENT
700mA
–
+
• Remote Load Sensing for
VIN
VIN
VIN
VIN
(–)
2
3
6
7
THERMAL
SHUTDOWN
Accurate Load Regulation
• 8-Pin DP Package
UVLO
5
VOUT
(–)
UDG-99030
DESCRIPTION
The UCC384 family of negative linear series pass regula- Short circuit current is internally limited. The device re-
tors is tailored for low drop out applications where low sponds to a sustained over current condition by turning
quiescent power is important. Fabricated with
BCDMOS technology ideally suited for low input to out- riod, TOFF, that is 40 times the TON delay. The device
put differential applications, the UCC384 will pass 0.5A then begins pulsing on and off at the TON/ OFF duty cycle
a
off after a TON delay. The device then stays off for a pe-
T
while requiring only 0.2V of input voltage headroom. of 2.5%. This drastically reduces the power dissipation
Drop out voltage decreases linearly with output current, during short circuit such that heat sinking, if at all re-
so that drop out at 50mA is less than 20mV.
quired, must only accommodate normal operation. An
external capacitor sets the on time. The off time is al-
Quiescent current consumption for the device under nor-
mal (non-drop out) conditions is typically 200µA. An inte-
ways 40 times TON
.
grated charge pump is internally enabled only when the The UCC384 can be shutdown to 45µA (maximum) by
device is operating near drop out with low VIN. This pulling the SD/CT pin more positive than –0.6V. To allow
guarantees that the device will meet the drop out specifi- for simpler interfacing, the SD/CT pin may be pulled up
cations even for maximum load current and a VIN of to +6V above the ground pin without turning on clamping
–3.2V with only a modest increase in quiescent current. diodes.
Quiescent current is always less than 350µA, with the
charge pump enabled. Quiescent current of the UCC384
does not increase with load current.
Internal power dissipation is further controlled with ther-
mal overload protection circuitry. Thermal shutdown oc-
curs if the junction temperature exceeds 140°C. The chip
will remain off until the temperature has dropped 20°C.
SLUS234A - JANUARY 2000