Datasheet
SLUS317B − JANUARY 2000 − REVISED FEBRUARY 2004
4
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
electrical characteristics, T
A
= −40°C to 100°C for the UC282-X series and 0°C to 100°C for the
UC382-X, VB = 5 V, VIN = 3.3 V, VOUT = 2.5 V for the UC382-ADJ, T
A
= T
J
, (unless otherwise stated)
UC382-ADJ adjustable, 3-A family
PARAMETERS TEST CONDITIONS MIN TYP MAX UNITS
ADJ voltage (I
VOUT
= 100 mA)
UC382-ADJ 1.188 1.200 1.212 V
ADJ voltage (I
VOUT
= 100 mA)
UC282-ADJ 1.176 1.200 1.212 V
Load regulation I
VOUT
= 10 mA to 3 A 0.5 4 mV
VIN PSSR VOUT programmed for 2.5 V 80 100 dB
VB PSSR VOUT programmed for 2.5 V 50 60 dB
I
VOUT
= 3 A, T
J
= 25°C 350 425 mV
VIN dropout voltage = VIN−VOUT
I
VOUT
= 3 A, UC382-ADJ 350 450 mV
VIN dropout voltage = VIN−VOUT
I
VOUT
= 3 A, UC282-ADJ 350 500 mV
VB dropout = VB−VOUT
I
VOUT
= 3 A, UC382-ADJ 1.8 2.10 V
VB dropout = VB−VOUT
I
VOUT
= 3 A, UC282-ADJ 1.8 2.20 V
Short circuit current limit 3.3 4.5 A
VB current
I
VOUT
= 10 mA 6 11 mA
VB current
I
VOUT
= 3 A 18 60 mA
VIN current I
VOUT
= 3 A 2.94 2.97 A
pin descriptions
ADJ: In the adjustable version, the user programs the output voltage with two external resistors. The resistors
should be 0.1% for high accuracy. The output amplifier is configured as a non-inverting-operational amplifier.
The resistors should meet the criteria of R3 || R4 < 100 Ω. Connect ADJ to VOUT for an output voltage of 1.2 V.
Note that the point at which the feedback network is connected to the output is the Kelvin sense point. For -1,
-2, and -3 versions, ADJ pin is tied to VOUT to obtain specified output voltage.
GND: For accurate results, the GND pin should be referenced to the load ground.
VB: Supplies power to all circuits of the regulator except the collector of the output-power transistor. The 2-V
headroom from VB to VOUT allows the use of a Darlington output stage for inherently-low-output impedance
and fast response. (Dropout is derated for junction temperatures below 0°C.)
VIN: Supplies the current to the collector of the output-power transistor only. The dropout (VIN−VOUT) is under
100 mV for light loads; maximum dropout is 450 mV at 3 A for T
J
= 0°C to 100°C. (Dropout is derated for junction
temperatures over 100°C.) At full load, the majority of the VB current is going to the load.
VOUT: This pin should be connected to the load via a low impedance path. Avoid connectors which add
significant inductance and resistance. Note that even though a Kelvin sense is available through a 5-pin
package, care must be taken since voltage drops along wire traces add to the dropout voltage.