ISO-9001 CERTIFIED BY DSCC
M.S.KENNEDY CORP.
NEGATIVE, 3 AMP,
LOW DROPOUT
VOLTAGE REGULATOR
5332
SERIES
(315) 701-6751
4707 Dey Road Liverpool, N.Y. 13088
FEATURES:
-5V, -5.2V, -10V, -12V and -15V Standard Versions
Low Dropout Voltage
Output Current to 3 Amps
Output Voltage Internally Set to ±1% MAX.
Internal Short Circuit Current Limit
Internal Thermal Overload Protection
Lead Form Options: Straight, Up, Down and Gull Wing
Alternate Output Voltages Available
Available with Top Tab or Tabless Package
MIL-PRF-38534 CERTIFIED
TOP TAB
NO TAB
DESCRIPTION:
The MSK 5332 is a fixed, negative voltage regulator which offers low dropout and output voltage accuracy to ±1%
maximum. The low
θjc
combined with low dropout allows increased output current and excellent device efficiency. The
MSK 5332 offers both internal current limit and thermal overload protection. The case of the device is electrically isolated
for heat sinking purposes. The device is packaged in a space efficient 3 pin power package with various lead form options.
The MSK 5332 series is also available in a power package with a top tab to accomodate direct mounting to a heat sink.
EQUIVALENT SCHEMATIC
TYPICAL APPLICATIONS
High Efficiency Linear Regulators
Constant Voltage/Current Regulators
System Power Supplies
Switching Power Supply Post Regulators
PIN-OUT INFORMATION
1 GND
2 VIN
3 VOUT
1
Rev. B 8/05
APPLICATION NOTES
BYPASS CAPACITORS
For most applications a 33uF minimum, low ESR (0.5-2 ohm)
tantalum capacitor should be attached as close to the regulator's
output as possible. This will effectively lower the regulator's
output impedance, increase transient response and eliminate any
oscillations that are normally associated with low dropout regu-
lators. Additional bypass capacitors can be used at the remote
load locations to further improve regulation. These can be either
of the tantalum or the electrolytic variety. Unless the regulator
is located very close to the power supply filter capacitor(s), a
4.7uF minimum low ESR (0.5-2 ohm) tantalum capacitor should
also be added to the regulator's input. An electrolytic may also
be substituted if desired. When substituting electrolytic in place
of tantalum capacitors, a good rule of thumb to follow is to
increase the size of the electrolytic by a factor of 10 over the
tantalum value.
OVERLOAD SHUTDOWN
The MSK 5332 features both power and thermal overload
protection. When the maximum power dissipation is not ex-
ceeded, the regulator will current limit slightly above its 3 amp
rating. As the Vin-Vout voltage increases, however, shutdown
occurs in relation to the maximum power dissipation curve. If
the device heats enough to exceed its rated die junction tem-
perature due to excessive ambient temperature, improper heat
sinking etc., the regulator will shutdown until an appropriate
junction temperature is maintained. It should also be noted that
in the case of an extreme overload, such as a sustained direct
short, the device may not be able to recover. In these instances,
the device must be shut off and power reapplied to eliminate the
shutdown condition.
HEAT SINKING
To determine if a heat sink is required for your application
and if so, what type, refer to the thermal model and govern-
ing equation below.
Governing Equation: Tj = Pd x (R
θ
jc + R
θ
cs + R
θ
sa) + Ta
WHERE
Tj = Junction Temperature
Pd = Total Power Dissipation
R
θ
jc = Junction to Case Thermal Resistance
R
θ
cs = Case to Heat Sink Thermal Resistance
R
θ
sa = Heat Sink to Ambient Thermal Resistance
Tc = Case Temperature
Ta = Ambient Temperature
Ts = Heat Sink Temperature
EXAMPLE:
This example demonstrates an analysis where the regulator is at
one-half of its maximum rated power dissipation, which occurs
when the output current is at 1.5 amps.
Conditions for MSK 5332-5:
Vin = -7.0V; Iout = -1.5A
1.) Assume 45° heat spreading model.
2.) Find regulator power dissipation:
LOAD REGULATION
For best results the ground pin should be connected directly
to the load as shown below, this effectively reduces the ground
loop effect and eliminates excessive voltage drop in the sense
leg. It is also important to keep the output connection between
the regulator and the load as short as possible since this directly
affects the load regulation. For example, if 20 gauge wire were
used which has a resistance of about .008 ohms per foot, this
would result in a drop of 8mV/ft at 1Amp of load current. It is
also important to follow the capacitor selection guidelines to
achieve best performance. Refer to Figure 1 for connection dia-
gram.
MSK 5332 TYPICAL APPLICATION:
Low Dropout Negative Power Supply
FIGURE 1
Pd = (Vin - Vout)(Iout)
Pd = (-7-(-5))(-1.5)
= 3.0W
3.) For conservative design, set Tj = +125°C Max.
4.) For this example, worst case Ta = +90°C.
5.) R
θ
jc = 7.0°C/W from the Electrical Specification Table.
6.) R
θ
cs = 0.15°C/W for most thermal greases.
7.) Rearrange governing equation to solve for R
θ
sa:
R
θ
sa= ((Tj - Ta)/Pd) - (R
θ
jc) - (R
θ
cs)
= (125°C - 90°C)/3.0W - 7.0°C/W - 0.15°C/W
= 4.5°C/W
In this case the result is 4.5°C/W. Therefore, a heat sink with a
thermal resistance of no more than 4.5°C/W must be used in
this application to maintain the regulator junction temperature
under 125°C.
3
Rev. B 8/05
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