B29152J-3.3 View Datasheet(PDF) - Bay Linear
Part Name
Description
MFG CO.
'B29152J-3.3' PDF : 5 Pages View PDF
APPLICATION HINTS
The Bay Linear B29150/51/52/53 incorporates protection against
over-current faults, reversed load insertion, over temperature
operation, and positive and negative transient voltage. However, the
use of an output capacitor is required in order to insure the stability
and the performances.
Thermal Consideration
Although the B29150/51/52/53 offers limiting circuitry for overload
conditions, it is necessary not to exceed the maximum junction
temperature, and therefore to be careful about thermal resistance. The
heat flow will follow the lowest resistance path, which is the Junction-
to-case thermal resistance. In order to insure the best thermal flow of
the component, a proper mounting is required. Note that the case of
the device is electrically connected to the output. The
case has to be electrically isolated, a thermally conductive spacer can
be used. However do not forget to consider its contribution to thermal
resistance.
Assuming:
VIN = 10V, VOUT = 5V, IOUT = 1.5A, TA = 90°C, θCASE= 1°C/W (no
external heat sink, no wind)
Power dissipation under these conditions
PD = (VIN – VOUT) * IOUT = 7.5W
Junction Temperature
TJ = TA + PD * (θCASE+ θJC)
For the Control Section
TJ = 90°C + 7.5W*(1°C/W + 0.6°C/W) = 102°C
114°C < TJUNCTION MAX for the control section.
For the Power Section
TJ = 90°C + 7.5W*(1°C/W + 1.6°C/W) = 104.5°C
109.5°C < TJUNCTION MAX for the power transistor.
In both case reliable operation is insured by adequate junction
temperature.
Capacitor Requirements
The output capacitor is needed for stability and to minimize the output
noise. The required value of the capacitor varies with the load.
However, a minimum value of 10µF Aluminum will guarantee
stability over load. A tantalum capacitor is recommended for a fast
load transient response.
If the power source has high AC impedance, a 0.1µF capacitor
between input & ground is recommended. This capacitor should have
good characteristics up to 250 kHz.
B29150
Minimum Load Current
To ensure a proper behavior of the regulator at light load, a
minimum load of 5mA for B29150/51/52/53 is required.
Adjustable Regulator Design
B29152/53 are adjustable regulators and maybe programmed for
any value between 1.25V and 16V using two resistors. The relation
between the resistors is given by:
R1=R2 (VOUT/1.240 –1)
Resistors have a large value up to 1mΩ in order to reduce the
current consumption. This might be interesting in the case of
widely varying load currents.
Error Flag
B29152/53 features an error indicating either an over current fault
or a low input voltage. This flag pulls low when such a problem
occurs and may sink 10mA. It is inoperative during thermal
shutdown.
Enable Input
B29152/53 features enable input allowing turning ON & OFF the
device. EN has been designed to be compatible with TTL/CMOS
logic. When the regulator is ON, the current flowing through this
pin is approximately 20µA.
VIN
BAY
B29150
V OU
T
Fig.1 Basic Fixed Output Regulator
1
4
BAY
VOUT
VIN
2 B29152
3
5
R1
VOUT = VREF X [1 + (R1/
R2
R2)]
For best results, the total series resistance should be small
enough to pass the minimum regulator load current
Fig. 2 Adjustable Output Voltage Regulator
Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556
www.baylinear.com
Share Link: 
