Replacement of
CS5205-XX
MIK5205-XX
5 A Low Dropout Positive
Voltage Regulator
June 1999 - revised August 2000
Description
The MIK5205 series of positive adjustable and fixed regulators are designed to provide 5A with higher efficiency than currently available
devices. All internal circuitry is designed to operate down to 500 mV input to output differential and the dropout voltage is fully specified
as a function of load current. Dropout voltage of the device is 100 mV at light loads and rising to 500 mV at maximum output current. A
second low current input is required to achieve this dropout. The MIK5205 can also be used as a single supply device (3 pin version).
On-chip trimming adjusts the reference voltage to 1%. Current limit is also trimmed, minimizing the stress on both the regulator and
power source circuitry under overload conditions. The MIK5205 series are ideal to power the next generation of advanced
microprocessor on motherboards where both 5V and 3.3V supplies are available.
Features
Adjustable or Fixed Output
Output Current of 5A
Low Dropout, 500 mV at 5A Output Current
0.015% Line Regulation
0.01% Load Regulation
100% Thermal Limit Burn-In
Fast Transient Response
Remote Sense
Applications
High Efficiency Linear Regulators
Post Regulators for Switching Supplies
Microprocessor Supply
Adjustable Power Supply
Typical application data2.5V, 5A
regulator
V
POWER
V
CONTROL
V
OUT
V
SENSE
Load
MIK5205
10 F
10V
5V
3.3V
100 F
5V
0.1 F
5V
300 F
5V
2.5V@5A
124
1%
124
1%
V
OUT
=
I
R2
ADJ
V
(1+R2/R1) +
REF
Adjust
R2
R1
Package information
Absolute Maximum Ratings
Symbol Parameter
Maximum
Units
P
D
Power Dissipation
Internally Limited
W
V
IN
Input Voltage
Vpower
Vcontrol
7
13
V
T
J
Operating Junction Temperature Range
o
C
Control Section
Power Transistor
0 to 125
0 to150
T
STG
Storage Temperature
-65 to 150
o
C
T
LEAD
Lead Temperature (Soldering, 10 sec)
300
o
C
Device Selection Guide
(Note1)
Device Output
Voltage
MIK5205 Adj
MIK5205-1.5 1.5V
MIK5205-2.5 2.5V
MIK5205-2.85 2.85V
MIK5205-3.0 3.0V
MIK5205-3.3 3.3V
MIK5205-3.5 3.5V
MIK5205-5.0 5.0V
Note 1: Other fixed versions are available Vout = 1.5V to 5.0V
Page 1 of 7
Replacement of
CS5205-XX
MIK5205-XX
5 A Low Dropout Positive
Voltage Regulator
June 1999 - revised August 2000
Electrical Characteristics
(Note 1)
Electrical Characteristics at I
LOAD
= 0 mA and T
J
= +25
C unless otherwise specified.
Parameter Device
Test
Conditions
Min
Typ
Max
Units
Reference Voltage MIK5205
V
CONTROL
= 2.75V, V
POWER
= 2V, I
LOAD
= 10mA
V
CONTROL
= 2.7V to 12V,
V
POWER
= 3.3V to 5.5V, I
LOAD
= 10mA to 5A
*
1.238
1.230
1.250
1.250
1.262
1.270
V
Output Voltage
MIK5205-1.5
V
CONTROL
= 4V, V
POWER
= 2V
V
CONTROL
= 3V, V
POWER
= 2.3V, I
LOAD
= 0mA to 5A
*
1.485
1.475
1.500
1.500
1.515
1.525
V
MIK5205-2.5
V
CONTROL
= 5V, V
POWER
= 3.3V
V
CONTROL
= 4V, V
POWER
= 3.3V, I
LOAD
= 0mA to 5A
*
2.475
2.460
2.500
2.500
2.525
2.540
V
MIK5205-2.85
V
CONTROL
= 5.35V, V
POWER
= 3.35V
V
CONTROL
= 4.4V, V
POWER
= 3.7V, I
LOAD
= 0mA to 5A
*
2.821
2.805
2.850
2.850
2.879
2.895
V
MIK5205-3.0
V
CONTROL
= 5.5V, V
POWER
= 3.5V
V
CONTROL
= 4.5V, V
POWER
= 3.8V, I
LOAD
= 0mA to 5A
*
2.970
2.950
3.000
3.000
3.030
3.050
V
MIK5205-3.3
V
CONTROL
= 5.8V, V
POWER
= 3.8V
V
CONTROL
= 4.8V, V
POWER
= 4.1V, I
LOAD
= 0mA to 5A
*
3.267
3.247
3.300
3.300
3.333
3.353
V
MIK5205-3.5
V
CONTROL
= 6V, V
POWER
= 4V
V
CONTROL
= 5V, V
POWER
= 4.3V, I
LOAD
= 0mA to 5A
*
3.465
3.445
3.500
3.500
3.535
3.555
V
MIK5205-5.0
V
CONTROL
= 7.5V, V
POWER
= 5.5V
V
CONTROL
= 6.5V, V
POWER
= 5.8V, I
LOAD
= 0mA to 5A
*
4.950
4.920
5.000
5.000
5.050
5.080
V
Line Regulation
All
I
LOAD
= 10mA, (1.5V+ V
OUT
)
V
CONTROL
12V,
0.8V
(V
POWER
- V
OUT
)
5.5V
*
0.04
0.20
%
Load Regulation
All
V
CONTROL
= V
OUT
+2.5V, V
POWER
= V
OUT
+ 0.8V,
I
LOAD
= 10mA to 5A
* 0.08
0.40 %
Minimum Load
Current (Note 2)
MIK5205 V
CONTROL
= 5V, V
POWER
= 3.3V, V
ADJ
= 0V
*
5
10
mA
Control Pin Current
(Note3)
All V
CONTROL
= V
OUT
+2.5V, V
POWER
= V
OUT
+ 0.8V,
I
LOAD
= 10mA to 5A
*
80 135
mA
Ground Pin Current MIK5205-1.5/
-2.5/-2.85/
-3.0/-3.3/-3.5/-
5.0
V
CONTROL
= V
OUT
+2.5V, V
POWER
= V
OUT
+ 0.8V,
I
LOAD
= 10mA to 5A
* 6 10
mA
Adjust Pin Current MIK5205
V
CONTROL
= 2.75V, V
POWER
= 2.05V,
I
LOAD
= 10mA
* 50
120 A
Current Limit
All
(V
IN
- V
OUT
) = 3V
*
5.5
6.8
A
Ripple Rejection
All
V
CONTROL
= V
POWER
= V
OUT
+ 2.5V, V
RIPPLE
= 1V
P-P
,
I
LOAD
= 2.5A
60 80
dB
Thermal Regulation MIK5205
T
A
= 25
C, 30 ms pulse
0.003
%/W
Dropout Voltage Note 4
Control Input
(V
CONTROL
- V
OUT
)
All V
POWER
= V
OUT
+0.8V, I
LOAD
= 10mA
V
POWER
= V
OUT
+ 0.8V, I
LOAD
= 5A
*
1.00
1.15
1.15
1.30
V
Power Input
(V
POWER
- V
OUT
)
All V
CONTROL
= V
OUT
+2.5V, I
LOAD
= 10mA
V
CONTROL
= V
OUT
+ 2.5V, I
LOAD
= 5A
*
0.10
0.55
0.17
0.70
V
The * denotes the specifications which apply over the full temperature range.
Note 1: Unless otherwise specified Vout = Vsense. For MIK5205 (adj) Vadj = 0V
Note 2: For the adjustable device the minimum load current is the minimum current required to maintain regulation. Normally the current
in the resistor divider used to set the output voltage is selected to meet the minimum load current requirement.
Note 3: The control pin current is the drive current required for the output transistor. This current will track output current with a ratio of
about 1:100.
Note 4: The dropout voltage for the MIK5205 is caused by either minimum control voltage or minimum power voltage.
The specifications represent the minimum input/output voltage required to maintain 1% regulation.
Page 2 of 7
Replacement of
CS5205-XX
MIK5205-XX
5 A Low Dropout Positive
Voltage Regulator
June 1999 - revised August 2000
Pin Functions (5-Lead)
Sense (Pin 1): This pin is the positive side of the reference
voltage. With this pin it is possible to Kelvin sense the output
voltage at the load.
Adjust (Pin 2): This pin is the negative side of the reference
voltage. Adding a small bypass capacitor from the Adjust pin to
ground improves the transient response. For fixed voltage
devices the Adjust pin is also brought out to allow the user to
add a bypass capacitor.
GND (Pin 2): For fixed voltage devices this is the bottom of the
resistor divider that sets the output voltage.
V
POWER
(Pin 5): This pin is the collector of the power transistor.
The output load current is supplied through this pin. The
voltage at this pin must be 0.7V greater than the output voltage
for the device to regulate.
V
CONTROL
(Pin 4): This pin is the supply pin for the control
circuitry. The current flow into this pin will be about 1% of the
output current. The voltage at this pin must be 1.3V greater
than the output voltage for the device to regulate.
Output (Pin 3): This is the power output of the device.
Block Diagram
Page 3 of 7
Replacement of
CS5205-XX
MIK5205-XX
5 A Low Dropout Positive
Voltage Regulator
June 1999 - revised August 2000
Application Information
The MIK5205 series of adjustable and fixed
regulators are designed to power the new generation of
microprocessors. The MIK5205 is designed to make use of
multiple power supplies, present in most systems, to reduce
the dropout voltage. One of the advantages of the two supply
approach is maximizing the efficiency.
The second supply is at least 1V greater than output
voltage and is providing the power for the control circuitry and
supplies the drive current to the NPN output transistor. This
allows the NPN output transistor to be driven into saturation.
For the control voltage the current requirement is small equal
to about 1% of the output current or approximately 50 mA for a
5A load. This drive current becomes part of the output current.
The maximum voltage on the Control pin is 12V. The
maximum voltage at the Power pin is 7V. By tying the control
and power inputs together the MIK5205 can also be operated
as a single supply device. In single supply operation the
dropout will be determined by the minimum control voltage.
The new generation of microprocessors cycle load
current from several hundred milliamperes to several amperes
in tens of nanoseconds. Output voltage tolerances are tighter
and include transient response as part of the specification.
Designed to meet the fast current load step requirements of
these microprocessors, the MIK5205 also saves total cost by
needing less output capacitance to maintain regulation.
Both the fixed and adjustable versions have remote
sense pins, permitting very accurate regulation of output
voltage. As a result, over an output current range of 100mA to
5A, the typical load regulation is less than 1mV. For the fixed
voltages the adjust pin is brought out allowing the user to
improve transient response by bypassing the internal resistor
divider. Optimum transient response is provided using a
capacitor in the range of 0.1
F to 1F for bypassing the Adjust
pin.
In addition to the enhancements mentioned, the
reference accuracy has been improved a factor of two with a
guaranteed initial tolerance of
1% at 25
0
C and 1.6% accuracy
over the full temperature and load current range.
Typical applications for the MIK5205 include 3.3V to
2.5V conversion with a 5V control supply, 5V to 4.2V
conversion with a 12V control supply or 5V to 3.6V conversion
with a 12V control supply. It is easy to obtain dropout voltages
of less than 0.5V at 2.5A along with excellent static and
dynamic specifications. The device is fully protected against
overcurrent and overtemperature conditions.
Grounding and Output Sensing
The MIK5205 allows true Kelvin sensing for both the
high and low side of the load. As a result the voltage regulation
at the load can be easily optimized. Voltage drops due to
parasitic resistances between the regulator and the load can
be placed inside the regulation loop. The advantages of
remote sensing are illustrated in figures 1 through 3.
Figure 1 shows the device connected as a
conventional 3 terminal regulator with the Sense lead
connected directly to the output of the device. R
P
is the
parasitic resistance of the connections between the device and
the load. Trace A of figure 3 illustrates the effect of Rp.
Figure 2 shows the device connected to take
advantage of the remote sense feature. The Sense pin and the
top of the resistor divider are connected to the top of the load;
the bottom of the resistor divider is connected to the bottom of
the load. The effect on output regulation can be seen in trace
B of figure 3.
It is important to note that the voltage drops due to
R
P
are not eliminated; they will add to the dropout voltage of
the regulator regardless. The MIK5205 can control the voltage
at the load as long as the input-output voltage is greater than
the total of the dropout voltage of the device plus the voltage
drop across R
P
.
POWER
SENSE
OUTPUT
ADJ
R
P
R
P
CONTROL
MIK5205
3.3V
5.0V
LOAD
R1
R2
Figure 1. Conventional Load Sensing
POWER
SENSE
OUTPUT
ADJ
R
P
R1
R2
R
P
CONTROL
MIK5205
3.3V
5.0V
LOAD
Figure 2. Remote Load Sensing
Figure 3. Remote Sensing Improves Load Regulation
Page 4 of 7
Replacement of
CS5205-XX
MIK5205-XX
5 A Low Dropout Positive
Voltage Regulator
June 1999 - revised August 2000
Stability
The circuit design used in the MIK5205 series
requires the use of an output capacitor as part of the device
frequency compensation. The addition of 150
F aluminum
electrolytic or a 22
F solid tantalum on the output will ensure
stability for all operating conditions. In order to meet the
transient performance of the processor larger value capacitors
are needed. To limit the high frequency noise generated by the
processor high quality bypass capacitors must be used. In
order to limit parasitic inductance (ESL) and resistance (ESR)
in capacitors to acceptable limits, multiple small ceramic
capacitor in addition to high quality solid tantalum capacitors
are required.
When the adjustment terminal is bypassed to
improve the ripple rejection, the requirement for an output
capacitor increases. The Adjust pin is brought out on the fixed
voltage device specifically to allow this capability. To further
improve stability and transient response of these devices
larger values of output capacitor can be used.
The modern processors generate large high frequency current
transients.
Figure 4.
The load current step contains higher order
frequency components than the output coupling network must
handle until the regulator throttles to the load current level.
Because they contain parasitic resistance and inductance,
capacitors are not ideal elements. These parasitic elements
dominate the change in output voltage at the beginning of a
transient load step change. The ESR of the output capacitors
produces an instantaneous step in output voltage
V=I(ESR).
The ESL of the output capacitors produces a droop
proportional to the rate of change of the output current
V=L(
I/t). The output capacitance produces a change in
output voltage proportional to the time until the regulator can
respond
V=t(I/C). Figure 4 illustrates these transient
effects.
Output Voltage
The MIK5205 (adjustable version) develops a 1.25V
reference voltage between the Sense pin and the Adjust pin
(Figure 5). Placing a resistor between these two terminals
causes a constant current to flow though R1 and down though
R2 to set the output voltage. In general R1 is chosen so that
this current is the specified minimum load current of 10 mA.
The current out of the Adjust pin is small, typically 50
A and it
adds to the current from R1. For best regulation the top of the
resistor divider should be connected directly to the Sense pin.
POWER
SENSE
OUTPUT
ADJ
R1
R2
V
OUT
I
ADJ
50 A
V
REF
V
OUT
=
I
R2
ADJ
V
(1+R2/R1) +
REF
V
POWER
V
CONTROL
CONTROL
MIK5205
+
+
+
Figure 5. Setting Output Voltage
Protection Diodes
In normal operation MIK5205 family does not need
any protection diodes between the adjustment pin and the
output and from the output to the input to prevent die
overstress. Internal resistors are limiting the internal current
paths on the ADJ pin. Therefore even with bypass capacitors
on the adjust pin no protection diode is needed to ensure
device safety under short-circuit conditions. The Adjust pin can
be driver on a transient basis
7V with respect to the output
without any device degradation.
A protection diode between the Output pin and
V
POWER
pin is not usually needed. Microsecond surge currents
of 50A to 100A can be handled by the internal diode between
the Output pin and V
POWER
pin of the device. In normal
operations it is difficult to get those values of surge currents
even with the use of large output capacitances. Only with high
value output capacitors, such as 1000
F to 5000F and the
V
POWER
pin is instantaneously shorted to ground, damage can
occur. A diode from output to input is recommended (Figure 6).
POWER
SENSE
OUTPUT
ADJ
D1
D2
R1
R2
V
OUT
V
POWER
V
CONTROL
CONTROL
MIK5205
+
+
+
Figure 6. Optional Clamp Diodes Protect Against Input
Crowbar Circuits
If MIK5205 is connected as a single supply device
with the control and power input pins shorted together the
internal diode between the output and the power input pin will
protect the control input pin.
Thermal Considerations
The MIK5205 series have internal power and
thermal limiting circuitry designed to protect the device under
overload conditions. However maximum junction temperature
ratings should not be exceeded under continuous normal load
conditions. Careful consideration must be given to all sources
of thermal resistance from junction to ambient, including
junction-to-case, case-to-heat sink interface and heat sink
resistance itself.
Junction temperature of the Control section can run
up to 125
0
C. Junction temperature of the Power section can
run up to 150
0
C. Due to the thermal gradients between the
power transistor and the control circuitry there is a significant
difference in thermal resistance between the Control and
Power sections.
Virtually all the power dissipated by the device is
dissipated in the power transistor. The temperature rise in the
power transistor will be greater than the temperature rise in the
Control section making the thermal resistance lower in the
Control section. At power levels below 12W the temperature
gradient will be less than 25
0
C and the maximum ambient
temperature will be determined by the junction temperature of
the Control section. This is due to the lower maximum junction
temperature in the Control section. At power levels above 12W
the temperature gradient will be greater than 25
0
C and the
maximum ambient temperature will be determined by the
Power section. In both cases the junction temperature is
determined by the total power dissipated in the device. For
most low dropout applications the power dissipation will be
less than 12W.
Page 5 of 7
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