lt1123cz-pbf Linear Technology Corporation, lt1123cz-pbf Datasheet

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lt1123cz-pbf

Manufacturer Part Number
lt1123cz-pbf
Description
Low Dropout Regulator Driver
Manufacturer
Linear Technology Corporation
Datasheet
FEATURES
TYPICAL APPLICATIO
5.4 TO 7.2V
LEAD ACID
*REQUIRED IF DEVICE IS
REQUIRED FOR STABILITY
MORE THAN 6" FROM MAIN
FILTER CAPACITOR
(LARGER VALUES INCREASE
STABILITY)
Extremely Low Dropout
Low Cost
Fixed 5V Output, Trimmed to ±1%
700µA Quiescent Current
1mV Line Regulation
5mV Load Regulation
Thermal Limit
4A Output Current Guaranteed
Available in a 3-Pin TO-92 Package
SEALED
5V Low Dropout Regulator
+
10µF*
LT1123
DRIVE
GND
620Ω
20Ω
U
FB
+
MOTOROLA
MJE1123
LT1123 TA01
10µF
OUTPUT = 5V/4A
DESCRIPTIO
The LT
in conjunction with a discrete PNP power transistor to
form an inexpensive low dropout regulator. The LT1123
consists of a trimmed bandgap reference, error amplifier,
and a driver circuit capable of sinking up to 125mA from
the base of the external PNP pass transistor. The LT1123
is designed to provide a fixed output voltage of 5V.
The drive pin of the device can pull down to 2V at 125mA
(1.4V at 10mA). This allows a resistor to be used to reduce
the base drive available to the PNP and minimize the
power dissipation in the LT1123. The drive current of the
LT1123 is folded back as the feedback pin approaches
ground to further limit the available drive current under
short-circuit conditions.
Total quiescent current for the LT1123 is only 700µA. The
device is available in a low cost TO-92 package.
All other trademarks are the property of their respective owners.
, LTC and LT are registered trademarks of Linear Technology Corporation.
®
1123 is a 3-pin bipolar device designed to be used
0.5
0.4
0.3
0.2
0.1
0
0
1
U
Dropout Voltage
OUTPUT CURRENT (A)
Regulator Driver
2
Low Dropout
3
4
LT1123 TA02
5
LT1123
1123fb
1

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lt1123cz-pbf Summary of contents

Page 1

... Total quiescent current for the LT1123 is only 700µA. The device is available in a low cost TO-92 package. , LTC and LT are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. 0.5 MOTOROLA ...

Page 2

... V = 0.5V DRIVE 10mA 4.5V DRIVE 125mA 4.5V DRIVE FB 5V < V < 20V DRIVE ∆ 100mA DRIVE ORDER PART NUMBER FB GND LT1123CZ Z PACKAGE = 125°C, θ = 220°C MIN TYP MAX 4.90 5.00 5.10 ● 4.80 5.00 5.20 ● 300 500 ● 0.45 1.0 ● 125 170 25 ...

Page 3

W U TYPICAL PERFOR A Feedback Pin Bias Current vs Temperature 400 300 200 100 100 125 TEMPERATURE (°C) LT1123 G01 Feedback Pin Bias Current vs Feedback Pin Voltage 500 400 300 ...

Page 4

LT1123 CTIO S All internal circuitry connected to the drive pin is designed to operate at the saturation voltage of the Darlington output driver (1.4 to 2V). This allows a resistor to be inserted between ...

Page 5

U U APPLICATIO S I FOR ATIO The LT1123 is designed to be used in conjunction with an external PNP transistor. The overall specifications of a regulator circuit using the LT1123 and an external PNP will be heavily dependent on ...

Page 6

LT1123 U U APPLICATIO S I FOR ATIO Dropout Voltage DRIVE CURRENT OUTPUT CURRENT 20mA 1A 50mA 1A 2A 120mA 1A 4A 1.0 BASED ON MJE1123 SPECS 0. 120mA DRIVE 0. 20mA DRIVE 0. ...

Page 7

U U APPLICATIO S I FOR ATIO The following assumptions were made in calculating the data for the curves. Resistors are 5% tolerance and the values shown on the curve are nominal. For 20mA drive current assume 0.95V ...

Page 8

LT1123 U U APPLICATIO S I FOR ATIO The curve in Figure 6 can be used to determine the range of current limit of an LT1123 regulator circuit using an MJE1123 as a pass transistor. The curve was generated using ...

Page 9

U U APPLICATIO S I FOR ATIO voltage and resistor value. Power dissipation can be calculated using the following formula – V – DRIVE = where emitter/base voltage ...

Page 10

LT1123 U U APPLICATIO S I FOR ATIO PNP. If the output of the regulator circuit can be shorted, heat sinking must be adequate to limit the rate of tempera- ture rise of the power device to approximately 50°C/ minute. ...

Page 11

U TYPICAL APPLICATIO S Isolated Feedback for Switching Regulators V IN SWITCHING REGULATOR DRIVE LT1123 FB GND 5V/2A Regulator with Remote Sensing 600Ω 75Ω 7V DRIVE LT1123 1k 5V OUTPUT LT1123 TA03 5V Regulator with Antisat Miminizes Ground Pin Current ...

Page 12

LT1123 U TYPICAL APPLICATIO S 12 5V/1A Regulator with Shutdown 6V GEL CELL 620Ω 50k OFF 1/6 MM74C906 MPSA12 (OPEN COLLECTOR DRIVE OUTPUT) LT1123 FB + GND Undervoltage Indicator On for V < ...

Page 13

U TYPICAL APPLICATIO S INTERNAL BATTERY GEL CELL Battery Backup Regulator + 10µF 620Ω 620Ω ALUM 6V MJE1123 1N4148 1N4148 20Ω DRIVE 5V OUTPUT LT1123 FB + 10µF GND ALUM LT1123 TA07 Adjusting V OUT 620Ω V > ...

Page 14

LT1123 PACKAGE DESCRIPTIO .264 – .287 (6.70 – 7.30) .130 – .146 (3.30 – 3.71) .0905 (2.30) BSC .071 (1.80) MAX Package 3-Lead Plastic SOT-223 (Reference LTC DWG # 05-08-1630) .248 – .264 (6.30 – 6.71) .114 ...

Page 15

... NOM Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen- tation that the interconnection of circuits as described herein will not infringe on existing patent rights Package 3-Lead Plastic TO-92 (Similar to TO-226) (Reference LTC DWG # 05-08-1410) .180 ± ...

Page 16

... R3 R5 10V 10V 1.5k 1.5k MJE1123 MJE1123 MJE1123 R4 R6 820Ω 820Ω + LT1123 TA06 10µF 10V *PACKS WILL SHARE CURRENT REF = 30µ 20µA Q LT/LWI/LT 0505 REV B • PRINTED IN USA © LINEAR TECHNOLOGY CORPORATION 1992 10µF 10V 5V/1A OUTPUT 1123fb ...

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