UC2833Q_技术文档

UC1832/3

UC2832/3

UC3832/3

Precision Low Dropout Linear Controllers

FEATURES

DESCRIPTION

•

Precision 1% Reference

The UC1832 and UC1833 series of precision linear regulators include all the

control functions required in the design of very low dropout linear regulators.

Additionally, they feature an innovative duty-ratio current limiting technique

which provides peak load capability while limiting the average power dissipa-

tion of the external pass transistor during fault conditions. When the load cur-

rent reaches an accurately programmed threshold, a gated-astable timer is

enabled, which switches the regulator’s pass device off and on at an externally

programmable duty-ratio. During the on-time of the pass element, the output

current is limited to a value slightly higher than the trip threshold of the duty-ra-

tio timer. The constant-current-limit is programmable on the UCx832 to allow

higher peak current during the on-time of the pass device. With duty-ratio con-

trol, high initial load demands and short circuit protection may both be accom-

modated without extra heat sinking or foldback current limiting. Additionally, if

the timer pin is grounded, the duty-ratio timer is disabled, and the IC operates

in constant-voltage/constant-current regulating mode.

•

Over-Current Sense Threshold

Accurate to 5%

•

Programmable Duty-Ratio

Over-Current Protection

•

4.5V to 36V Operation

100mA Output Drive, Source or

Sink

•

Under-Voltage Lockout

Additional Features of the UC1832

series:

•

Adjustable Current Limit to

Current Sense Ratio

These IC’s include a 2 Volt (±1%) reference, error amplifier, UVLO, and a high

current driver that has both source and sink outputs, allowing the use of either

NPN or PNP external pass transistors. Safe operation is assured by the inclu-

sion of under-voltage lockout (UVLO) and thermal shutdown.

•

Separate +VIN terminal

Programmable Driver Current

Limit

The UC1833 family includes the basic functions of this design in a low-cost, 8-

pin mini-dip package, while the UC1832 series provides added versatility with

the availability of 14 pins. Packaging options include plastic (N suffix), or ce-

ramic (J suffix). Specified operating temperature ranges are: commercial (0°C

to 70°C), order UC3832/3 (N or J); industrial (–25°C to 85°C), order UC2832/3

(N or J); and military (–55°C to 125°C), order UC1832/3J. Surface mount

packaging is also available.

•

Access to V_REFand E/A(+)

Logic-Level Disable Input

BLOCK DIAGRAMS

UDG-92040

6/94

UC1832/3

UC2832/3

UC3832/3

ABSOLUTE MAXIMUM RATINGS

Supply Voltage +VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40V

Driver Output Current (Sink or Source) . . . . . . . . . . . . . 450mA

Driver Sink to Source Voltage . . . . . . . . . . . . . . . . . . . . . . . 40V

TRC Pin Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . –0.3V to 3.2V

Other Input Voltages. . . . . . . . . . . . . . . . . . . . . . . –0.3V to +VIN

Operating Junction Temperature (note 2) . . . –55°C to +150°C

Storage Temperature . . . . . . . . . . . . . . . . . . . –65°C to +150°C

Lead Temperature (Soldering, 10 Seconds) . . . . . . . . . . 300°C

Note 1: Unless otherwise indicated, voltages are referenced to

ground and currents are positive into, negative out of, the speci-

fied terminals.

Note 2: See Unitrode Integrated Circuits databook for

information regarding thermal specifications and limitations of

packages.

CONNECTION DIAGRAMS

UC1832

UC1833

DIL-14 (Top View)

J Or N Package

DIL-8 (Top View)

J Or N Package

SOIC-16 (Top View)

DW Package

SOIC-16 (Top View)

DW Package

PACKAGE PIN FUNCTION

LCC-20 & PLCC-20

L & Q Package

(Top View)

LCC-20 & PLCC-20

L & Q Package

(Top View)

FUNCTION

N/C

1

+VIN & C/S(+)

1

+VIN

2

N/C

2

Comp/Shutdown

E/A(+)

3

4

N/C

3

N/C

4

+2V REF

N/C

5

6

Comp/Shutdown

5

Gnd

6

Gnd

7

N/C

7

Logic Disable

Limit

8

9

N/C

8

N/C

9

Source

N/C

E/A(-)

Sink

VADJ

N/C

Timer RC

Current Sense(-)

Current Sense(+)

10

11

12

13

14

15-17

18

19

20

Source

N/C

E/A(-)

N/C

Sink

Timer RC

Current Sense(+)

N/C

10

11

12

13

14

15

16

17

18-20

2

UC1832/3

UC2832/3

UC3832/3

Unless otherwise stated, specifications hold for TA = 0°C to 70°C for the

UC3832/3, –25°C to 85°C for the UC2832/3, and –55°C to 125°C for the

UC1832/3, +VIN = 15V, Driver sink = +VIN, C/S(+) voltage = +VIN. TA=TJ.

ELECTRICAL CHARACTERISTICS:

PARAMETER

Input Supply

TEST CONDITIONS

MIN

TYP

MAX UNITS

Supply Current

+VIN = 6V

+VIN = 36V

6.5

9.5

3.3

10

15

mA

Logic Disable = 2V (UCx832 only)

Reference Section

Output Voltage (Note 3)

TJ = 25°C, IDRIVER = 10mA

over temperature, IDRIVER = 10mA

IOUT = 0 to 10mA

1.98

1.96

-10

2.00 2.02

V

2.00

-5.0

2.04

Load Regulation (UCx832 only)

Line Regulation

mV

mV/V

V

+VIN = 4.5 to 36V, IDRIVER = 10mA

0.033 0.5

Under-Voltage Lockout Threshold

Logic Disable Input (UCx832 only)

Threshold Voltage

3.6

4.5

1.3

1.4

1.5

V

Input Bias Current

Logic Disable = 0V

Over Temperature

-5.0

-1.0

µA

Current Sense Section

Comparator Offset

95

93

100

135

235

305

100

105

107

170

290

360

135

10

mV

µA

Amplifier Offset (UCx833 only)

Amplifier Offset (UCx832 only)

110

180

250

65

VADJ = Open

VADJ = 1V

VADJ = 0V

VCM = +VIN

Input Bias Current

Input Offset Current (UCx832 only) VCM = +VIN

-10

µA

Amplifier CMRR (UCx832 only)

Transconductance

VCM = 4.1V to +VIN+0.3V

80

65

-1

dB

±

ICOMP = 100µA

mS

µA

VADJ Input Current (UCx832 only)

VADJ = 0V

-10

Timer

Inactive Leakage Current

Active Pullup Current

Duty Ratio (note 4)

C/S(+) = C/S(-) = +VIN; TRC pin = 2V

0.25

-270

4.8

36

1.0

µA

%

C/S(+) = +VIN, C/S(-) = +VIN - 0.4V; TRC pin = 0V

ontime/period, RT = 200k, CT = 0.27µF

ontime + offtime, RT = 200k, CT = 0.27µF

-345

-175

Period (notes 4,5)

ms

V

Upper Trip Threshold (Vu)

Lower Trip Threshold (Vl)

Trip Threshold Ratio

Error Amplifier

1.8

0.9

2.0

V

Vu/Vl

V/V

Input Offset Voltage (UCx832 only) VCM = VCOMP = 2V

Input Bias Current VCM = VCOMP = 2V

Input Offset Current (UCx832 only) VCM = VCOMP = 2V

-8.0

-4.5

-1.5

50

8.0

1.5

mV

µA

dB

mS

V

-1.1

AVOL

VCOMP = 1V to 13V

70

80

CMRR (UCx832 only)

PSRR (UCx832 only)

Transconductance

VOH

VCM = 0V to +VIN - 3V

VCM = 2V, +VIN = 4.5 to 36V

60

90

±

ICOMP = 10µA

4.3

.95

.45

-500

ICOMP = 0, Volts below +VIN

ICOMP = 0

1.3

0.7

VOL

V

IOH

VCOMP = 2V

-700

-100

µA

3

UC1832/3

UC2832/3

UC3832/3

Unless otherwise stated, specifications hold for TA = 0°C to 70°C for the UC3832/3, –25°C to

85°C for the UC2832/3, and –55°C to 125°C for the UC1832/3, +VIN = 15V, Driver sink =

+VIN, C/S(+) voltage = +VIN. TA=TJ.

ELECTRICAL

CHARACTERISTICS (cont.)

PARAMETER

Error Amplifier (cont.)

IOL

TEST CONDITIONS

MIN

TYP

MAX UNITS

VCOMP = 2V, C/S(-) = +VIN

100

2

500

6

700

µA

VCOMP = 2V, C/S(-) = +VIN - 0.4V

mA

Driver

Maximum Current

Driver Limit & Source pins common; TJ = 25°C

Over Temperature

200

100

300

400

450

mA

Limiting Voltage (UCx832 only)

Driver Limit to Source voltage at current limit,

ISOURCE = -10mA; TJ = 25°C (Note 6)

TJ = 25°C (Note 6)

.72

2.4

V

Ω

Internal Current Sense Resistance

Pull-Up Current at Driver Sink

Compensation/Shutdown = 0.4V; Driver Sink = +VIN - 1V -800

Compensation/Shutdown = 0.4V, +VIN = 36V; Driver

-300

-100

µA

Sink = 35V

Pull-Down Current at Driver Source Compensation/Shutdown = 0.4V; Driver Source = 1V

-1000 -300

-75

µA

V

150

300

1.5

700

Saturation Voltage Sink to Source

Maximum Source Voltage

Driver Source = 0V; Driver Current = 100mA

Driver Sink = +VIN, Driver Current = 100mA

Volts below +VIN

3.0

25

V

UVLO Sink Leakage

+VIN = C/S(+) = C/S(-) = 2.5V, Driver Sink = 15V, Driver

Source = 0V, TA = 25°C

µA

Maximum Reverse Source Voltage Compensation/Shutdown = 0V; ISOURCE = 100µA,

+VIN = 3V

1.6

V

Thermal Shutdown

160

°C

Note 3: On the UCx833 this voltage is defined as the regulating level at the error amplifier inverting input, with the error amplifier

driving VSOURCE to 2V.

Note 4: These parameters are first-order supply-independent, however both may vary with supply for +VIN less than about 4V. This

supply variation will cause a slight change in the timer period and duty cycle, although a high off-time/on-time ratio will be main-

tained.

±

Note 5: With recommended RT value of 200k, TOFF ≈ RT CT * ln(Vu/Vl) 10%.

Note 6: The internal current limiting voltage has a temperature dependence of approximately -2.0mV/°C, or -2800ppm/°C. The inter-

nal 2.4 Ω sense resistor has a temperature dependance of approximately +1500ppm/°C.

APPLICATION AND OPERATION INFORMATION

NPN Pass (Local 100mA Regulator) (UCx833)

UDG-92041-1

4

UC1832/3

UC2832/3

UC3832/3

APPLICATION AND OPERATION INFORMATION (cont.)

PNP Pass (Low Drop-Out Regulator) (UCx833)

UDG-92042-1

NPN Pass (Medium Power, Low Drop-Out Regulator) (UCx832)

UDG-92043-1

Estimating Maximum Load Capacitance

For any power supply, the rate at which the total output

capacitance can be charged depends on the maximum

output current available and on the nature of the load. For

a constant-current current-limited power supply, the out-

put will come up if the load asks for less than the maxi-

mum available short-circuit limit current.

Current Sense Amplifier OffsetVoltage

and

K =

100mA

≈1.35 for UCx833, and is variable from 1.35 to 3.05

with VADJ for the UCx832.

For a worst-case constant-current load of value just less

than ITH, CMAX can be estimated from:

To guarantee recovery of a duty-ratio current-limited

power supply from a short-circuited load condition, there

is a maximum total output capacitance which can be

charged for a given unit ON time. The design value of ON

time can be adjusted by changing the timing capacitor.

Nominally, TON = 0.693 x 10k x CT.

TON

VOUT

CMAX = ((K−1)ITH) (

),

where VOUT is the nominal regulator output voltage.

For a resistive load of value RL, the value of CMAX can be

estimated from:

TON

RL

1

VOUT

K • ITH • RL

CMAX =

•

.

Typically, the IC regulates output current to a maximum of

IMAX = K x ITH, where ITH is the timer trip-point current,

−1

In [(1−

)

]

5

UC1832/3

UC2832/3

UC3832/3

APPLICATION AND OPERATION INFORMATION (cont.)

Current Sense Amplifier Offset Voltage vs VADJ

UCx832/33 Timer Function

UCx832/33 Current Sense Input Configuration

Load current, timing capacitor voltage, and output voltage of

the regulator under fault conditions.

6

UC1832/3

UC2832/3

UC3832/3

APPLICATION AND OPERATION INFORMATION (cont.)

UNITRODE CORPORATION

7 CONTINENTAL BLVD. • MERRIMACK, NH 03054

TEL. (603) 424-2410 • FAX (603) 424-3460

7

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pertaining to warranty, patent infringement, and limitation of liability.

TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in

accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent

TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily

performed, except those mandated by government requirements.

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型号：	UC2833Q
厂家：	ETC
描述：	Positive Adjustable Voltage Regulator 正，可调式稳压器\n 稳压器
文件：	总8页 (文件大小：762K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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