SLUS212F − NOVEMBER 1999 − REVISED MAY 2009
D
D
D
D
D
D
D
D
5-PIN TO-220
T PACKAGE (TOP VIEW)
Fast Transient Response
10-mA to 5-A Load Current
Short Circuit Protection
Maximum Dropout of 500-mV at 5-A Load
Current
Separate Bias (VB) and VIN Pins
Available in Adjustable or Fixed Output
Voltages
5-Pin Package Allows Kelvin Sensing of
Load Voltage
Reverse Current Protection
5-PIN TO-263
TD PACKAGE
(TOP VIEW)
Note: Tab = Ground
description
The UC385 is a low dropout linear regulator providing a quick response to fast load changes. Combined with
its precision onboard reference, the UC385 excels at driving GTL and BTL buses. Due to its fast response to
load transients, the total capacitance required to decouple the regulator’s output can be significantly decreased
when compared to standard LDO linear regulators.
Dropout voltage (VIN to VOUT) is only 490 mV maximum and 350 mV typical at 5-A load (0°C to 100°C).
The onboard bandgap reference is stable with temperature and scaled for a 1.2 V input to the internal power
amplifier. The UC385 is available in fixed output voltages of 1.5 V, 2.1 V, or 2.5 V. The output voltage of the
adjustable version can be set with two external resistors. If the external resistors are omitted, the output voltage
defaults to 1.2 V.
block diagram
VB
1
UC382−ADJ
UC382−1 (1.5 V)
UC382−2 (2.1 V)
UC382−3 (2.5 V)
R1
R2
OPEN
2 kΩ
2 kΩ
2 kΩ
0
500 Ω
1.5 k Ω
2.16 k Ω
THERMAL
SHUTDOWN
2
1.2 V
BANDGAP
REFERENCE
VIN
+
SHORT
CIRCUIT
SENSE
R2
R1
3
5
4
GND
ADJ
VOUT
UDG-00084
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
All trademarks are the property of their respective owners.
Copyright 1998−2009, Texas Instruments Incorporated
!" # $%&" !# '%()$!" *!"&+
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""0 !)) '!!&"&#+
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1
SLUS212F − NOVEMBER 1999 − REVISED MAY 2009
absolute maximum ratings over operating free-air temperature (unless otherwise noted)†
VB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 V
VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5 V
Output voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 V to −6.0 V
Storage temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −65°C to 150°C
Junction temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −55°C to 150°C
Lead temperature (soldering, 10 seconds) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300°C
† Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
AVAILABLE OPTIONS(1)
PACKAGED DEVICES
TO−263 (TD)(2)
TO-220 (T)
TJ
OUTPUT VOLTAGE
OUTPUT VOLTAGE
1.5 V
2.1 V
2.5 V
1.2 V or ADJ
1.5 V
2.1 V
2.5 V
1.2 V or ADJ
–40°C to 100°C
285T-1
285T-2
285T-3
285T-ADJ
285TD-1
285TD-2
285TD-3
285TD-ADJ
0°C to 100°C
385T-1
385T-2
385T-3
385T-ADJ
385TD-1
385TD-2
385TD-3
385TD-ADJ
1. For more package and ordering information, see the Package Option Addendum located at the end of this data sheet.
2. For 50 piece reel, add KTTT (e.g., UC285TDKTTT−1); for 500 piece reel, add TR (e.g., UC285TDTR−1).
electrical characteristics unless otherwise stated, these parameters apply for TA = −40°C to 100°C
for the UC285-x series and 0°C to 100°C for the UC385-x, VB = 5 V; VIN = 3.3 V, VOUT = 2.5 V, TA = TJ.
PARAMETER
TEST CONDITION
MIN
TYP
MAX
UNIT
2.475
2.5
2.525
V
2.45
2.5
2.525
0.5
4
UC385-3 Fixed 2.5 V, 5-A Family
Output voltage
UC385-3
UC285-3
Load regulation
IVOUT = 100 mA
IVOUT = 100 mA
IVOUT = 10 mA to 5 A
VIN PSRR
80
VB PSRR
50
VIN dropout voltage (VIN - VOUT)
UC385-3
UC285-3
VB dropout (VB - VOUT)
IVOUT = 5 A,
IVOUT = 5 A
UC385-3
IVOUT = 5 A
IVOUT = 5 A
UC285-3
IVOUT = 5 A
TJ = 25°C
Short circuit current limit
110
IVOUT = 10 mA
IVOUT = 5 A
VIN current
IVOUT = 5 A
dB
65
dB
350
425
mV
350
490
mV
350
500
mV
1.8
2.1
V
1.8
2.2
V
5.1
VB current
V
mV
7.5
A
8
15
mA
40
100
mA
4.9
4.96
A
2.079
2.1
2.121
V
2.058
2.1
2.121
V
0.5
4
VIN PSRR
80
110
dB
VB PSRR
50
67
dB
UC385-2 Fixed 2.1 V, 5-A Family
Output voltage
UC385-2
UC285-2
Load regulation
2
IVOUT = 100 mA
IVOUT = 100 mA
IVOUT = 10 mA to 5 A
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mV
SLUS212F − NOVEMBER 1999 − REVISED MAY 2009
electrical characteristics unless otherwise stated, these parameters apply for TA = −40°C to 100°C
for the UC285-x series and 0°C to 100°C for the UC385-x, VB = 5 V; VIN = 3.3 V, VOUT = 2.5 V, TA = TJ.
PARAMETER
TEST CONDITION
MIN
TYP
MAX
UNIT
350
425
mV
350
490
mV
350
500
mV
UC385-2
IVOUT = 5 A
IVOUT = 5 A
1.8
2.1
V
UC285-2
IVOUT = 5 A
1.8
2.2
V
UC385−2 Fixed 2.1 V, 5-A Family (continued)
VIN dropout voltage (VIN - VOUT)
UC385-2
UC285-2
VB dropout (VB - VOUT)
IVOUT = 5 A,
IVOUT = 5 A
TJ = 25°C
Short circuit current limit
5.1
VB current
IVOUT = 10 mA
IVOUT = 5 A
VIN current
IVOUT = 5 A
7.5
A
8
15
mA
40
100
mA
4.9
4.96
A
1.485
1.5
1.515
1.470
1.5
1.515
0.5
4
UC385−1 Fixed 1.5 V, 5-A Family
Output voltage
UC385-1
UC285-1
Load regulation
IVOUT = 100 mA
IVOUT = 100 mA
IVOUT = 10 mA to 5 A
VIN PSRR
80
110
VB PSRR
50
65
VIN dropout voltage (VIN - VOUT)
UC285-1
UC285-2
VB dropout (VB - VOUT)
IVOUT = 5 A,
IVOUT 5 A
UC385-1
IVOUT = 5 A
IVOUT = 5 A
UC285-1
IVOUT = 5 A
TJ = 25°C
Short circuit current limit
IVOUT = 10 mA
IVOUT = 5 A
VIN = current
IVOUT = 5 A
V
mV
dB
dB
350
425
mV
350
490
mV
350
500
mV
1.8
2.1
V
1.8
2.2
V
7.5
A
8
15
mA
40
100
mA
5.1
VB current
V
4.9
4.96
A
1.188
1.2
1.212
V
1.176
1.2
1.212
V
0.5
4
110
UC385-ADJ Adjustable, 5-A Family
ADJ voltage
UC385-ADJ
UC285-ADJ
Load regulation
IVOUT - 100 mA
IVOUT - 100 mA
VIN PSRR
IVOUT = 10 mA to 5 A
VOUT programmed for 2.5 V
80
VB PSRR VOUT
Programmed for 2.5 V
50
VIN dropout voltage (VIN - VOUT)
IVOUT = 5 A,
IVOUT = 5 A
UC385-ADJ
UC285-ADJ
VB dropout (VB - VOUT)
VIN current
dB
65
dB
350
425
mV
350
490
mV
IVOUT = 5 A
IVOUT = 5 A
350
500
mV
UC385-ADJ
1.8
2.1
V
UC285-ADJ
IVOUT = 5 A
1.8
2.2
V
Short circuit current limit
VB current
TJ = 25°C
mV
5.1
IVOUT = 10 mA
IVOUT = 5 A
IVOUT = 5 A
www.ti.com
4.9
7.5
A
8
15
mA
40
100
mA
4.96
A
3
SLUS212F − NOVEMBER 1999 − REVISED MAY 2009
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 noninverting 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.
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 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 490 mV at 5 A for TJ = 0°C to 100°C. (Dropout is derated for junction
temperatures over 100°C.)
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.
DROPOUT VOLTAGE (VIN − VOUT)
vs.
LOAD CURRENT
DROPOUT VOLTAGE (VB − VOUT)
vs.
LOAD CURRENT
400
VDO - Dropout Voltage (VIN − VOUT) − mV
VDO − Dropout Voltage (VB − VOUT) − V
1.7
TJ = 27°C
1.675
1.65
1.625
300
200
100
1.6
0
1
2
3
4
5
5
100m
IL− Load Current − A
IL− Load Current − A
Figure 2
Figure 1
4
TJ = 27°C
www.ti.com
SLUS212F − NOVEMBER 1999 − REVISED MAY 2009
APPLICATION INFORMATION
The UC385 is easy to use. The adjustable version requires two resistors to set the output voltage. The fixed
versions of the UC385 require no external resistors. All versions of the UC385 require decoupling capacitors
on the input and output. In a typical application, VB and VIN are driven from switching power supplies which
may have large filter capacitors at their outputs. If the UC385 is further than 12 inches from the power supply,
it is recommended to add local decoupling as close as possible to the linear regulator.
Decouple the output of the UC385 with at least 100 µF of high quality tantalum or Sanyo OSCON capacitors
close to the VOUT pin for maximum stability. Many applications involving ultrafast GTL or BTL applications
require additional capacitance close to the load. The exact amount will vary according to speed and magnitude
of the load transients and the tolerance allowed for transients on VOUT. When specifying the decoupling
capacitors, the series resistance of the capacitor bank is an important factor in its ability to filter load transients.
The UC385 allows for Kelvin sensing the voltage at the load. This improves regulation performance and
eliminates the voltage drops due to wire trace resistance. This voltage drop must be added to the headroom
(VIN to VOUT and VB to VOUT). The dropout of 350 mV is measured at the pins and does not include additional
drops due to trace resistance.
OPEN LOOP PHASE
vs.
FREQUENCY
OPEN LOOP GAIN
vs.
FREQUENCY
0
70
60
CO = 100 µF
IL = 1 A
CO = 100 µF
IL = 1 A
Gain - dB
Phase - deg
50
−90
40
30
20
10
0
−180
−10
100
1k
10 k
100 k
1M
10 M
100
1k
10 k
100 k
1M
10 M
f − Frequency − Hz
f − Frequency − Hz
Figure 4
Figure 3
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5
SLUS212F − NOVEMBER 1999 − REVISED MAY 2009
APPLICATION INFORMATION
PSSR - Power Supply Rejection Ratio (VB Input) − dB
POWER SUPPLY REJECTION RATIO (VB INPUT)
vs.
FREQUENCY
60
50
40
30
20
10
0
100
1k
10 k
100 k
1M
10 M
f − Frequency − Hz
Figure 5
1µ F
Ceramic
+
_
5V
1
2
+
+
_
3.3 V
4.7µ F
Tantalum
VIN
VB
VOUT
4
+
UC385−ADJ
GND
ADJ
IRF
520
VO = 1.2 V
100µ F
Tantalum
121Ω
R1
5
Pulse
Generator
3
UDG-00085
Figure 6. Transient Test Circuit
6
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SLUS212F − NOVEMBER 1999 − REVISED MAY 2009
APPLICATION INFORMATION
10 mA to 3 A/µs Load Transient Response
20
10
0
−10
3
−20
2
1
0
I O − Load Current − A
∆ VO − Change in
Output Voltage − mV
2 µs/DIV
Figure 7
+5 V
+
4.7µ F
Kelvin
Sense
Point
1
+3.3 V
2
+
4.7 µ F
VIN
VB
VOUT
4
R3
60 Ω
UC385−ADJ
GND
ADJ
+ 330 µ F
OSCON
+1.8 V
Output
F
2.2 µ
Ceramic
5
R4
120 Ω
3
UDG-00086
Figure 8. Typical UC385-ADJ Application
www.ti.com
7
SLUS212F − NOVEMBER 1999 − REVISED MAY 2009
APPLICATION INFORMATION
+5 V
+
4.7 µ F
Kelvin
Sense
Point
1
2
VIN
VB
VOUT
+
UC385−1
GND
+1.5 V
Output
4
ADJ
330 µ F
OSCON
2.2 µF
Ceramic
5
3
UDG-00087
Figure 9. Typical UC385-1, -2, or -3 Application
8
www.ti.com
SLUS212F − NOVEMBER 1999 − REVISED MAY 2009
Revision History
DATE
REV
PAGE
SECTION
5/09
F
2
Absolute Maximum Ratings
DESCRIPTION
Added VB.
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
www.ti.com
9
PACKAGE OPTION ADDENDUM
www.ti.com
13-Aug-2021
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
UC285T-3
ACTIVE
TO-220
KC
5
50
RoHS & Green
Call TI | SN
N / A for Pkg Type
-40 to 85
UC285T-3
UC285T-ADJ
ACTIVE
TO-220
KC
5
50
RoHS & Green
Call TI | SN
N / A for Pkg Type
-40 to 100
UC285T-ADJ
UC285T-ADJG3
ACTIVE
TO-220
KC
5
50
RoHS & Green
SN
N / A for Pkg Type
-40 to 100
UC285T-ADJ
UC285TDKTTT-1
ACTIVE
DDPAK/
TO-263
KTT
5
50
RoHS & Green
Call TI | SN
Level-2-260C-1 YEAR
-40 to 85
UC285TD-1
UC285TDKTTT-3
ACTIVE
DDPAK/
TO-263
KTT
5
50
RoHS & Green
Call TI | SN
Level-2-260C-1 YEAR
-40 to 85
UC285TD-3
UC285TDKTTT-ADJ
ACTIVE
DDPAK/
TO-263
KTT
5
50
RoHS & Green
Call TI | SN
Level-2-260C-1 YEAR
-40 to 100
UC285TD-ADJ
UC385T-1
ACTIVE
TO-220
KC
5
50
RoHS & Green
Call TI | SN
N / A for Pkg Type
UC385T-1
UC385T-2
ACTIVE
TO-220
KC
5
50
RoHS & Green
Call TI | SN
N / A for Pkg Type
UC385T-2
UC385T-3
ACTIVE
TO-220
KC
5
50
RoHS & Green
Call TI | SN
N / A for Pkg Type
UC385T-3
UC385T-ADJ
ACTIVE
TO-220
KC
5
50
RoHS & Green
Call TI | SN
N / A for Pkg Type
UC385T-ADJ
UC385TDTR-1
ACTIVE
DDPAK/
TO-263
KTT
5
500
RoHS & Green
Call TI | SN
Level-2-260C-1 YEAR
0 to 70
UC385TD-1
UC385TDTR-3
ACTIVE
DDPAK/
TO-263
KTT
5
500
RoHS & Green
Call TI | SN
Level-2-260C-1 YEAR
0 to 70
UC385TD-3
UC385TDTR-ADJ
ACTIVE
DDPAK/
TO-263
KTT
5
500
RoHS & Green
Call TI | SN
Level-2-260C-1 YEAR
0 to 70
UC385TD-ADJ
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
Addendum-Page 1
Samples
PACKAGE OPTION ADDENDUM
www.ti.com
13-Aug-2021
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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