Datasheet

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FEATURES SUPPORTS DEFENSE, AEROSPACE AND

VIN

SD/CT

VOUT

VIN

VOUTS

VIN

GND

DESCRIPTION

UCC284-EP

www.ti.com

....................................................................................................................................... SLVS862A – NOVEMBER 2008 – REVISED NOVEMBER 2008

LOW-DROPOUT 0.5-A NEGATIVE LINEAR REGULATOR

MEDICAL APPLICATIONS

• Precision Negative Series Pass Voltage

• Controlled Baseline

Regulation

• One Assembly/Test Site

• 0.2-V Dropout at 0.5 A

• One Fabrication Site

• Wide Input Voltage Range – 3.2 V to – 15 V

• Available in S-Temp ( – 55 ° C/100 ° C)

• Low Quiescent Current Irrespective of Load D

Temperature Range

(1)

Simple Logic Shutdown Interfacing

• Extended Product Life Cycle

• – 5 V, – 12 V, and Adjustable Output

• Extended Product-Change Notification

• 2.5% Duty Cycle Short Circuit Protection

• Product Traceability

(1) Additional temperature ranges are available – contact factory.

D PACKAGE

(FRONT VIEW)

The UCC284-x family of negative linear-series pass regulators is tailored for low-dropout applications where

low-quiescent power is important. Fabricated with a BCDMOS technology ideally suited for low input-to-output

differential applications, the UCC284-x passes 0.5 A while requiring only 0.2 V of input-voltage headroom.

Dropout voltage decreases linearly with output current, so that dropout at 50 mA is less than 20 mV.

Quiescent current consumption for the device under normal (non-dropout) conditions is typically 200 µ A. An

integrated charge pump is internally enabled only when the device is operating near dropout with low VIN. This

ensured that the device meets the dropout specifications even for maximum load current and a VIN of – 3.2 V

with only a modest increase in quiescent current. Quiescent current is always less than 360 µ A, with the charge

pump enabled. The quiescent current of the UCC284 does not increase with load current.

Short-circuit current is internally limited. The device responds to a sustained overcurrent condition by turning off

after a t

delay. The device then stays off for a period, t

OFF

, that is 40 times the t

delay. The device then

begins pulsing on and off at the t

OFF

duty cycle of 2.5%. This drastically reduces the power dissipation during

short circuit such that heat sinking, if at all required, must only accommodate normal operation. An external

capacitor sets the on time. The off time is always 40 times t

The UCC284-x can be shutdown to 45 µ A (maximum) by pulling the SD/CT pin more positive than – 0.7 V. To

allow for simpler interfacing, the SD/CT pin may be pulled up to 6 V above the ground pin without turning on

clamping diodes.

Internal power dissipation is further controlled with thermal-overload protection circuitry. Thermal shutdown

occurs if the junction temperature exceeds 140 ° C. The chip remains off until the temperature has dropped 20 ° C

= 120 ° C).

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.

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.

Summary of content (21 pages)

PAGE 1
UCC284-EP www.ti.com ....................................................................................................................................... SLVS862A – NOVEMBER 2008 – REVISED NOVEMBER 2008 LOW-DROPOUT 0.5-A NEGATIVE LINEAR REGULATOR FEATURES 1 • • • • • • Precision Negative Series Pass Voltage Regulation 0.2-V Dropout at 0.5 A Wide Input Voltage Range –3.2 V to –15 V Low Quiescent Current Irrespective of Load D Simple Logic Shutdown Interfacing –5 V, –12 V, and Adjustable Output 2.
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UCC284-EP SLVS862A – NOVEMBER 2008 – REVISED NOVEMBER 2008 ....................................................................................................................................... www.ti.
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UCC284-EP www.ti.com .......................................................................................................................................
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UCC284-EP SLVS862A – NOVEMBER 2008 – REVISED NOVEMBER 2008 ....................................................................................................................................... www.ti.com ELECTRICAL CHARACTERISTICS (continued) TA = –55°C to 100°C for the UCC284, VIN = VOUT – 1.5 V, IOUT = 0 mA, COUT = 4.7 µF, and CT = 0.015 µF. For UCC284-ADJ, VOUT is set to –3.3 V (unless otherwise noted) PARAMETER Peak current limit MIN TYP MAX TA = 25°C, VOUT = 0 V TEST CONDITIONS 0.7 1.1 1.
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UCC284-EP www.ti.com ....................................................................................................................................... SLVS862A – NOVEMBER 2008 – REVISED NOVEMBER 2008 ELECTRICAL CHARACTERISTICS (continued) TA = –55°C to 100°C for the UCC284, VIN = VOUT – 1.5 V, IOUT = 0 mA, COUT = 4.7 µF, and CT = 0.015 µF. For UCC284-ADJ, VOUT is set to –3.3 V (unless otherwise noted) PARAMETER Dropout voltage, VOUT - VIN TEST CONDITIONS MIN IOUT 0.5 A, VOUT = –3.
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UCC284-EP SLVS862A – NOVEMBER 2008 – REVISED NOVEMBER 2008 ....................................................................................................................................... www.ti.com VOUTS: This is the feedback pin for sensing the output of the regulator. For the UCC284-5 and UCC284-12 versions, VOUTS can be connected directly to VOUT.
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UCC284-EP www.ti.com ....................................................................................................................................... SLVS862A – NOVEMBER 2008 – REVISED NOVEMBER 2008 APPLICATION INFORMATION overview The UCC284–x family of negative low-dropout linear (LDO) regulators provides a regulated-output voltage for applications with up to 0.5 A of load current.
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UCC284-EP SLVS862A – NOVEMBER 2008 – REVISED NOVEMBER 2008 ....................................................................................................................................... www.ti.com short-circuit protection The UCC284 provides unique short-circuit protection circuitry that reduces power dissipation during a fault. When an overcurrent condition is detected, the device enters a pulsed mode of operation, limiting the output to a 2.5% duty cycle.
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UCC284-EP www.ti.com ....................................................................................................................................... SLVS862A – NOVEMBER 2008 – REVISED NOVEMBER 2008 t OFF t ON t OFF t ON t ON IOUT=0A ~40 x tON ~40 x tON IOUT (NOM) IOVER IPEAK NOTE: CURRENT FLOW IS INTO THE DEVICE VOUT = 0V VOUT =(IPEAK)(RL) VOUT NOM. (−V) CT = 0V CT (NOM) = − 1.6V CT = − 2.6V UDG−99031 Figure 5.
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UCC284-EP SLVS862A – NOVEMBER 2008 – REVISED NOVEMBER 2008 ....................................................................................................................................... www.ti.com short-circuit timing During normal operation the output voltage is in regulation and the SD/CT pin is held to -1.5 V via a 50-kΩ internal-source impedance. If the output-current rises above the overcurrent threshold, the CT capacitor is charged by a 40-µA current sink.
PAGE 11
UCC284-EP www.ti.com ....................................................................................................................................... SLVS862A – NOVEMBER 2008 – REVISED NOVEMBER 2008 UCC284−ADJ OVERCURRENT CONDITION OPERATION 1 ms/div Figure 6. UCC284−ADJ OVERCURRENT CONDITION OPERATION 25 ms/div Figure 7. shutdown feature of the UCC284 The shutdown feature of the UCC284 allows the device to be placed in a low quiescent current mode.
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UCC284-EP SLVS862A – NOVEMBER 2008 – REVISED NOVEMBER 2008 ....................................................................................................................................... www.ti.com TTL SHUTDOWN CIRCUIT +5 V +5 V LOGIC INPUT 470 k GND (+) (+) 0.015µF CT 4 R2 GND 8 SD/CT + VIN CIN VOUTS COUT 4.7µF C1 UCC384−ADJ 1 µF VOUT VIN VIN VIN VIN 2 3 6 7 VOUT + 1 R1 (−) 5 (−) Figure 8.
PAGE 13
UCC284-EP www.ti.com ....................................................................................................................................... SLVS862A – NOVEMBER 2008 – REVISED NOVEMBER 2008 VIN TO VOUT DELAY TIME DURING POWER-UP WITH CT = 0.22 µF Figure 9. VIN to VOUT Delay During power-up there is a delay between VIN and VOUT. The majority of this delay time is due to the charging time of the CT capacitor.
PAGE 14
UCC284-EP SLVS862A – NOVEMBER 2008 – REVISED NOVEMBER 2008 ....................................................................................................................................... www.ti.com With the quick start-up circuit, the delay time between VIN and VOUT during start-up can be reduced dramatically. Figure 11 shows that with the quick start-up circuit, the VIN to VOUT delay time has been reduced to approximately 1 ms. VIN TO VOUT DELAY TIME WITH QUICK START-UP CIRCUIT Figure 11.
PAGE 15
UCC284-EP www.ti.com ....................................................................................................................................... SLVS862A – NOVEMBER 2008 – REVISED NOVEMBER 2008 R3 along with C2 set the time that Q1 is allowed to be on. Since tM is the maximum amount of time that Q1 should be allowed to stay on, an added safety margin may be to use 0.9 × tM instead. This ensures that Q1 is turned off in the proper amount of time.
PAGE 16
PACKAGE OPTION ADDENDUM www.ti.com 10-Dec-2008 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Eco Plan (2) Qty UCC284SDR-5EP ACTIVE SOIC D 8 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR V62/09609-01XE ACTIVE SOIC D 8 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR Lead/Ball Finish MSL Peak Temp (3) (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs.
PAGE 17
PACKAGE MATERIALS INFORMATION www.ti.com 10-Dec-2008 TAPE AND REEL INFORMATION *All dimensions are nominal Device UCC284SDR-5EP Package Package Pins Type Drawing SOIC D 8 SPQ Reel Reel Diameter Width (mm) W1 (mm) 2500 330.0 12.4 Pack Materials-Page 1 A0 (mm) B0 (mm) K0 (mm) P1 (mm) 6.4 5.2 2.1 8.0 W Pin1 (mm) Quadrant 12.
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PACKAGE MATERIALS INFORMATION www.ti.com 10-Dec-2008 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) UCC284SDR-5EP SOIC D 8 2500 346.0 346.0 29.
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IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.