MIC5190
Micrel
MIC5190
Ultra High-Speed, High-Current Active Filter/LDO Controller
General Description
Features
The MIC5190 is an ultra high-speed linear regulator. It uses
an external N-Channel FET as its power device.
The MIC5190 offers ultra high-speed to cope with the fast
load demands of microprocessor cores, ASICs, and other
high-speed devices. Signal bandwidths of greater than 500kHz
can be achieved with a minimum amount of capacitance
while at the same time keeping the output voltage clean,
regardless of load demand. A powerful output driver delivers
large MOSFETs into their linear regions, achieving ultra-low
dropout voltage.
1.25VIN±10% can be turned into 0.9V ±1% without the use of
a large amount of capacitance.
MIC5190 (0.5V reference) is optimized for output voltages of
below 1.0V.
The MIC5190 is offered in 10-lead 3mm × 3mm MLF™ and
10-lead MSOP-10 packages and has an operating junction
temperature range of –40°C to +125°C.
All support documentation can be found on Micrel’s web
site at www.micrel.com.
• Input voltage range:
VIN = 0.9V to 5.5V
• +1.0% initial output tolerance
• Dropout down to 25mV@10A
• Filters out switching frequency noise on input
• Very high large signal bandwidth >500kHz
• PSRR >40dB at 500kHz
• Adjustable output voltage down to 0.5V
• Stable with any output capacitor
• Excellent line and load regulation specifications
• Logic controlled shutdown
• Current limit protection
• 3mm × 3mm 10-lead MLF™ and MSOP-10 packages
• Available –40°C to +125°C junction temperature
Applications
• Distributed power supplies
• ASIC power supplies
• DSP, µP, and µC power supplies
Typical Application
VCC = 12V
C1
0.01µF
VIN =1.2V
VOUT = 0.9V@7A
IR3716S
MIC5190
IS
OUT
VIN
VCC1
FB
VCC2
PGND
EN
C3
0.01µF
R1
100Ω
R2
125Ω
C2
10µF
SGND
COMP
R3
12.5kΩ
GND
GND
MicroLeadFrame and MLF are trademarks of Amkor Technology, Inc.
PowerPAK is a trademark of Siliconix, Inc.
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
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MIC5190
Micrel
Ordering Information
FB
Output Output
Part Number
Voltage Current Voltage
Standard
Pb-Free
MIC5190BML MIC5190YML
0.5V
ADJ
ADJ
MIC5190BMM MIC5190YMM
0.5V
ADJ
ADJ
Junction Temp. Range
Package
–40°C to +125°C
–40°C to +125°C
10-pin MLF™
MSOP-10
Pin Configuration
VIN 1
FB 2
SGND 3
VCC1 4
COMP 5
10 IS
VIN 1
9 PGND
FB 2
8 OUT
SGND 3
7 VCC2
VCC1 4
6 EN
COMP 5
MLF™-10 (ML)
10 IS
9 PGND
8 OUT
7 VCC2
6 EN
MSOP-10 (MM)
Pin Description
Pin Number
Pin Name
1
VIN
Input voltage (Current Sense +).
2
FB
Feedback input to error amplifier.
3
SGND
Signal ground.
4
VCC1
Supply to the internal voltage regulator.
5
COMP
Error amplifier output for external compensation.
6
EN
7
VCC2
Power to output driver.
8
OUT
Output drive to gate of power MOSFET.
9
PGND
Power ground.
10
IS
Current sense.
December 2005
Pin Function
Enable (Input): CMOS-compatible.
Logic high = Enable, Logic low = Shutdown. Do not float pin.
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MIC5190
Micrel
Absolute Maximum Ratings(1)
Operating Ratings(3)
Supply Voltage (VIN) .................................................. +6.0V
Enable Input Voltage (VEN) ......................................... +14V
VCC1, VCC2 ............................................................... +14V
Junction Temperature (TJ) ................ –40°C ≤ TJ ≤ +125°C
ESD ......................................................................... Note 2
Supply Voltage (VIN) ................................... +0.9V to +5.5V
Enable Input Voltage (VEN) ................................. 0V to VCC
VCC1,VCC2 ............................................... +4.5V to +13.2V
Junction Temperature (TJ) ................ –40°C ≤ TJ ≤ +125°C
Package Thermal Resistance
MLF™ (θJA)(4) ..................................................... 60°C/W
MSOP (θJA) (5) .............................................................. 200°C/W
Electrical Characteristics(6)
TA = 25°C with VIN = 1.2V, VCC = 12V, VOUT = 0.5V; bold values indicate –40°C < TJ < +125°C; unless otherwise specified.
Parameter
Condition
Output Voltage Accuracy
At 25°C
Over temperature range
Output Voltage Line Regulation
Min
VIN = 1.2V to 5.5V
Feedback Voltage
Typ
Max
Units
–1
+1
%
–2
+2
%
–0.1
0.005
+0.1
%/V
0.495
0.5
0.505
V
0.02
0.5
%
Output Voltage Load Regulation
IL = 10mA to 1A
VCC Pin Current (VCC1 + VCC2)
Enable = 0V
40
VCC Pin Current (VCC1 + VCC2)
Enable = 5V
15
20
mA
VIN Pin Current
Current from VIN
10
15
µA
13
30
µA
50
70
mV
25
100
µs
FB Bias Current
Current Limit Threshold
35
Start-up Time
VEN = VIN
Enable Input Threshold
Regulator enable
0.8
Regulator shutdown
Enable Pin Input Current
0.6
0.5
Enable Hysteresis
µA
V
0.2
V
100
mV
VIL < 0.2V (Regulator shutdown)
100
nA
VIH > 0.8V (Regulator enabled)
100
nA
Notes:
1. Exceeding the absolute maximum ratings may damage the device.
2. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.
3. The device is not guaranteed to function outside its operating ratings.
4. Per JESD 51-5 (1S2P Direct Attach Method).
5. Per JESD 51-3 (1S0P).
6. Specification for packaged product only.
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Typical Characteristics
0.501
0.5
0.499
0.498
0.499
0.498
12.5
11.5
0.495
9.5
20 40 60 80 100 120
Temp (C)
10.5
0.497
0.496
8.5
0.497
0.496
0.495
-40 -20 0
0.501
0.5
7.5
0.496
0.495
0 1 2 3 4 5 6 7 8 9 10
Output Current (A)
0.504
0.503
0.502
6.5
0.498
0.497
VOUT vs. VCC Voltage
0.505
5.5
0.5
0.499
VOUT vs. Temperature
Vout (V)
0.503
0.502
0.501
Vout (V)
Output Voltage (V)
0.505
0.504
0.503
0.502
4.5
Load Regulation
0.505
0.504
VCC Current
vs. VCCVoltage
0.8
0.5
10
8
6
Feedback Current
vs. Temperature
13.5
40
VCC (V)
13.5
12.5
11.5
10.5
9.5
8.5
7.5
6.5
Enable Time
vs. VCC Voltage
5.5
4.5
50
45
40
35
30
25
20
15
10
5
0
0
-40 -20 0 20 40 60 80 100 120
Temperature ( °C)
45
12.5
VCC Voltage(V)
5
50
11.5
13.5
12.5
11.5
10.5
9.5
8.5
7.5
6.5
4.5
5.5
10
10
55
10.5
11
15
60
9.5
12
20
8.5
13
65
CURRENT LIMIT (mA)
Feedback Current (µA)
14
Current Limit Threshold
vs. Vcc Voltage
7.5
25
9
4
2
0
-40 -20 0 20 40 60 80 100 120
Temperature (°C)
6.5
13.5
12.5
11.5
9.5
10.5
8.5
7.5
6.5
VCC Voltage (V)
CC
15
5.5
4.5
13.5
12.5
11.5
9.5
10.5
8.5
7.5
6.5
5.5
0.3
5.5
0.4
Feedback Current
Voltage
vs. V
Feedback Current (µA)
Input Current ( µA)
ENTH (V)
0.6
0.2
Input Current
vs. Temperature
20
18
16
14
12
0.7
VCC Voltage (V)
Enable Time (µsec)
Enable Threshold
vs. VCC Voltage
4.5
20
18
16
14
12
10
8
6
4
2
0
4.5
Input Current (mA)
Vcc (V)
VCC (V) Voltage
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Functional Characteristics
Disable Transient
ENABLE
(1V/div)
ENABLE
(1V/div)
OUTPUT
(500mV/div)
OUTPUT
(500mV/div)
Enable Transient
TIME (100µs/div)
TIME (10µs/div)
10A Load Transient
December 2005
LOAD CURRENT OUTPUT
(5A/div)
(10mV/div)
LOAD CURRENT
(5A/div)
OUTPUT
(10mV/div)
INPUT
(100mV/div)
INPUT
(100mV/div)
Transient Response
TIME (100µs/div)
5
TIME (100µs/div)
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Functional Diagram
VCC1
INTERNAL
VOLTAGE
REGULATOR
50mV
VIN
IS
CURRENT LIMIT
AMPLIFIER
VCC2
EN
ENABLE
OUTPUT
CONTROL
AND
LEVEL
SHIFT
OUT
PGND
FB
0.5V
ERROR
AMPLIFIER
SGND
COMP
Figure 1. MIC5190 Block Diagram
Enable
The MIC5190 comes with an active-high enable pin that
allows the regulator to be disabled. Forcing the enable pin low
disables the regulator and sends it into a low off-modecurrent state. Forcing the enable pin high enables the output
voltage. The enable pin cannot be left floating; a floating
enable pin may cause an indeterminate state on the output.
FB
The feedback pin is used to sense the output voltage for
regulation. The feedback pin is compared to an internal 0.5V
reference and the output adjusts the gate voltage accordingly
to maintain regulation. Since the feedback biasing current is
typically 13µA, smaller feedback resistors should be used to
minimize output voltage error.
COMP
COMP is the external compensation pin. This allows complete control over the loop to allow stability for any type of
output capacitor, load currents and output voltage. A detailed
explanation of how to compensate the MIC5190 is in the
“Designing with the MIC5190” section.
SGND, PGND
SGND is the internal signal ground which provides an isolated ground path from the high current output driver. The
signal ground provides the grounding for noise sensitive
circuits such as the current limit comparator, error amplifier
and the internal reference voltage.
PGND is the power ground and is the grounding path for the
output driver.
Functional Description
VIN
The VIN pin is connected to the N-Channel drain. VIN is the
input power being supplied to the output. This pin is also used
to power the internal current limit comparator and compare
the ISENSE voltage for current limit. The voltage range is
from 0.9V min to 5.5V max.
ISENSE
The ISENSE pin is the other input to the current limit comparator. The output current is limited when the ISENSE pin's
voltage is 50mV less than the VIN pin. In cases where there
is a current limited source and there isn’t a need for current
limit, this pin can be tied directly to VIN. Its operating voltage
range, like the VIN pin, is 0.9V min to 5.5V max.
VCC1, VCC2
VCC1 supplies the error amplifier and internal reference,
while VCC2 supplies the output gate drive. For this reason,
ensure these pins have good input capacitor bypassing for
better performance. The operating range is from 4.5V to
13.2V and both VCC pins should be tied together. Ensure that
the voltage supplied is greater than a gate-source threshold
above the output voltage for the N-Channel MOSFET selected.
Output
The output drives the external N-Channel MOSFET and is
powered from VCC. The output can sink and source over
150mA of current to drive either an N-Channel MOSFET or an
external NPN transistor. The output drive also has short
circuit current protection.
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Applications Information
∆V =
Designing with the MIC5190
Anatomy of a transient response
Output voltage variation will depend on two factors: loop
bandwidth and output capacitance. The output capacitance
will determine how far the voltage will fall over a given time.
With more capacitance, the drop in voltage will fall at a
decreased rate. This is the reason that more capacitance
provides a better transient response for the same given
bandwidth.
Load Current
The measure of a regulator is how accurately and effectively
it can maintain a set output voltage, regardless of the load's
power demands. One measure of regulator response is the
load step. The load step gauges how the regulator responds
to a change in load current. Figure 2 is a look at the transient
response to a load step.
Output Voltage
AC-Coupled
1
∫ idt
C
∆V ↓=
∆V = L
di
V=
The time it takes for the regulator to respond is directly
proportional to its bandwidth gain. Higher bandwidth control
loops respond quicker causing a reduced drop on the supply
for the same amount of capacitance.
1
∫ idt
C
dt
1
BW
Output voltage vs. time
during recovery is
directly proportional to
gain vs. frequency.
1
∫ idt ↓
C
Final recovery back to the regulated voltage is the final phase
of transient response and the most important factors are gain
and time. Higher gain at higher frequency will get the output
voltage closer to its regulation point quicker. The final settling
point will be determined by the load regulation, which is
proportional to DC (0Hz) gain and the associated loss terms.
∆V ↓=
Time
Figure 2. Typical Transient Response
At the start of a circuit's power demand, the output voltage is
regulated to its set point, while the load current runs at a
constant rate. For many different reasons, a load may ask for
more current without warning. When this happens, the regulator needs some time to determine the output voltage drop.
This is determined by the speed of the control loop. So, until
enough time has elapsed, the control loop is oblivious to the
voltage change. The output capacitor must bear the burden
of maintaining the output voltage.
There are other factors that contribute to large signal transient response, such as source impedance, phase margin,
and PSRR. For example, if the input voltage drops due to
source impedance during a load transient, this will contribute
to the output voltage deviation by filtering through to the
output reduced by the loops PSRR at the frequency of the
voltage transient. It is straightforward: good input capacitance reduces the source impedance at high frequencies.
Having between 35° and 45° of phase margin will help speed
up the recovery time. This is caused by the initial overshoot
in response to the loop sensing a low voltage.
Compensation
The MIC5190 has the ability to externally control gain and
bandwidth. This allows the MIC5190 design to be individually
tailored for different applications.
In designing the MIC5190, it is important to maintain adequate phase margin. This is generally achieved by having
the gain cross the 0dB point with a single pole 20dB/decade
roll-off. The compensation pin is configured as Figure 3
demonstrates.
di
dt
Since this is a sudden change in voltage, the capacitor will try
to maintain voltage by discharging current to the output. The
first voltage drop is due to the output capacitor's ESL (equivalent series inductance). The ESL will resist a sudden change
in current from the capacitor and drop the voltage quickly. The
amount of voltage drop during this time will be proportional to
the output capacitor's ESL and the speed at which the load
steps. Slower load current transients will reduce this effect.
∆V = L
di
dt ↑
Placing multiple small capacitors with low ESL in parallel can
help reduce the total ESL and reduce voltage droop during
high speed transients. For high speed transients, the greatest
voltage deviation will generally be caused by output capacitor
ESL and parasitic inductance.
∆V ↓= L
Internal
Error Amplifier
3.42MΩ
Driver
20pF
di
dt
After the current has overcome the effects of the ESL, the
output voltage will begin to drop proportionally to time and
inversely proportional to output capacitance.
∆V ↓= L ↓
December 2005
1
∫ idt
↑C
External
Comp
Figure 3. Internal Compensation
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Micrel
This places a pole at 2.3 kHz at 80dB and calculates as
follows.
1
2π × 3.42MΩ × 20pF
FP = 2.32kHz
100
FP =
225
The Dominant Pole
1
Fp =
2 × 3 .42 M × Ccomp
80
180
135
180
60
135
40
90
20
45
0
0
-20
0.01
1
10
100
1000
Frequency (KHz)
90
R LOAD × COUT Pole
20
45
0
0
-45
0.01
0.1
1
10
100
1000
Frequency (KHz)
10000 100000
Figure 6. External Compensation
Frequency Response
It is recommended that the gain bandwidth should be designed to be less than 1 MHz. This is because most capacitors lose capacitance at high frequency and becoming resistive or inductive. This can be difficult to compensate for and
can create high frequency ringing or worse, oscillations.
By increasing the amount of output capacitance, transient
response can be improved in multiple ways. First, the rate of
voltage drop vs. time is decreased. Also, by increasing the
output capacitor, the pole formed by the load and the output
capacitor decreases in frequency. This allows for the increasing of the compensation resistor, creating a higher mid-band
gain.
10000 100000
Figure 4. Internal Compensation
Frequency Response
There is single pole roll off. For most applications, an output
capacitor is required. The output capacitor and load resistance create another pole. This causes a two-pole system
and can potentially cause design instability with inadequate
phase margin. External compensation is required. By providing a dominant pole and zero–allowing the output capacitor
and load to provide the final pole–a net single pole roll off is
created, with the zero canceling the dominant pole. Figure 5
demonstrates placing an external capacitor (CCOMP) and
resistor (RCOMP) for the external pole-zero combination.
Where the dominant pole can be calculated as follows:
100
225
80
180
Gain (dB)
60
Internal
Error Amplifier
3.42MΩ
2 × Rcomp × Ccomp
-20
-45
0.1
Fz =
40
1
Driver
Increasing COUT reduces
the load resistance and
output capacitor pole
allowing for an increase
in mid-band gain.
40
135
90
20
45
0
0
Phase (Deg)
80
Phase (Deg)
225
Gain (dB)
100
Gain (dB)
External Zero
Phase (Deg)
60
20pF
-20
0.01
External
Comp
Figure 5. External Compensation
1
2π × 3.42MΩ × CCOMP
And the zero can be calculated as follows:
1
2π × RCOMP × CCOMP
This allows for high DC gain, and high bandwidth with the
output capacitor and the load providing the final pole.
December 2005
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100
1000
Frequency (KHz)
10000 100000
This will have the effect of both decreasing the voltage drop
as well as returning closer and faster to the regulated voltage
during the recovery time.
MOSFET Selection
The typical pass element for the MIC5190 is an N-Channel
MOSFET. There are multiple considerations when choosing
a MOSFET. These include:
• VIN to VOUT differential
• Output current
• Case size/thermal characteristics
• Gate capacitance (CISS
