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Bay Linear
Inspire the Linear Power
250mA Low Dropout Voltage Regulators
ON/OFF & BYPASS
B4251
Description
Features
The B4251 series are a group of positive output voltage,
five-pin regulators, which provide a high current even
when the input/output voltage differential is small. Low
power consumption and high accuracy is achieved
though CMOS and programmable fuse technologies.
Output voltage: 2.0V to 6.0V in 0.1V increments.
The B4251 consists of a high-precision voltage
reference, an error correction circuit, and a current
limited output driver. Key features include a Shutdown
Pin that reduces supply current to 0.5µA max and a
470pF Bypass input to ground reduces noise present on
the internal reference, which in turn significantly reduce
output noise. If output noise is not concern, this input
maybe left unconnected. Larger capacitor values cap be
used, but results in longer time period to rated output
voltage when power initially applied.
The ON/OFF pin enables the output to be turned off,
resulting in reduced power consumption. Provided in
SOT-25 (150mW) packages minimizes the usage of
board real state.
• Maximum Output Current: 250 mA.
• Highly Accurate Output Voltage +/- 1.4%
• Only 19µA Power Consumption MAX
• Shutdown Supply Current 1µA
• Ground Current of Less than 5µA
• Very Low Dropout
0.12V at 100mA
0.23V at 250mA
• Shutdown Mode for Power Savings
• With ON/OFF & BYPASS Features
• Offered in SOT-89 & SOT-25 Packages
• PIN-to-PIN S-818
Applications
• Battery Powered Equipment
• Notebook PC, Palmtops, PDA
• Portable Cameras and Video Recorders
• Reference Voltage Sources
• Cellular / GSM / PCS Phones
Pin Connection
SOT-25 (K5)
Vout Bypass
54
123
Vin ON/OFF
GND
Top View
SOT-89 (R)
Vout
Vss
54
1 23
NC Vin On/Off
Top View
Ordering Information
Package
Part No.
SOT-25
B4251CK5-X.X
SOT-89
B4251CR-X.X
X.X = Fixed Output Voltages from 2.0V to 6.0V
ON/OFF (Enable) Function
Part No
B4251
ON/Off
High
Low
VOUT
ON
OFF
Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 606-5950, Fax: (925) 940-9556
www.baylinear.com
B4251
Absolute Maximum Ratings
Parameter
Input Voltage
Output Current
Output Voltage
On/Off Voltage
Continual Total Power Dissipation
Operating Ambient Temperature
Storage Temperature
SOT-25
SOT-89
Symbol
VIN
IOUT
VOUT
On/Off
Pd
TOPR
TSTG
Ratings
12
500
VSS -0.3 to VIN 0.3
VSS -0.3 to VIN+ 0.3
150
300
-30 to 80
-40 to 125
Units
V
mA
V
V
mW
°C
°C
Electrical Characteristics (Ta = 25°C, VIN = VOUT + 0.5V; unless otherwise noted)
Parameter
Conditions
MIN TYP MAX
Output Voltage Accuracy
Line Regulation
∆VOUT/∆VIN-VOUT
IO = 1mA
IO = 0 to 150mA
IO= 100mA,
(VOUT + 0.1V)<VIN<6V
-1.4% - +1.4%
-2% - +2%
0.2 0.3
Load Regulation
VIN 6V, 0mA < IO < 120mA COUT = 1µF
0.01 0.04
Maximum Output Current
Current Limit
Shutdown Supply Current
Shutdown Input Bias Current
Shutdown Exit Delay
Shutdown Input Threshold Low
Shutdown Input Threshold High
Ground Pin Current
Dropout Voltage
Thermal Shutdown Temperature
TA=25°C
VSHDN=VIN, TA=25°C
CBP=0µF COUT=1µF, IO = 1mA
Vin=2.5 to 5.5V
Vin=2.5 to 5.5V
IOUT = 0mA……150mA
IO = 150mA
IO = 250 mA
250
160 500
0.01 1
0.01 100
30 150
0.4
2
25
160 250
200 280
155
UNIT
V
%/V
%/mV
mA
µA
nA
µsec
V
V
µA
mV
°C
Marking Format
SOT-25
FXWW
F = B4251
Variables
X = Voltage Codes
B = 2.0 F = 3.3
C = 2.5 G = 3.5
WW = Work Week Code
SOT-25 = 01 to 99
D = 2.8 H = 5.0
E = 3.0
Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 606-5950, Fax: (925) 940-9556
www.baylinear.com
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