MIC38300

MIC38300
HELDO®
3A High-Efficiency Low Dropout Regulator
General Description
The MIC38300 is a 3A peak, 2.2A continuous output
current step down converter. This is the first device in a
®
new generation of HELDO (High-Efficiency Low Dropout)
regulators that provide the benefits of an LDO in respect to
ease of use, fast transient performance, high PSRR, and
low noise while offering the efficiency of a switching
regulator.
As output voltages move lower, the output noise and
transient response of a switching regulator become an
increasing challenge for designers. By combining a
switcher whose output is slaved to the input of a highperformance LDO, high efficiency is achieved with a clean
low noise output. The MIC38300 is designed to provide
less than 5mV of peak to peak noise and over 70dB of
PSRR at 1kHz. Furthermore, the architecture of the
MIC38300 is optimized for fast load transients that allow
maintenance of less than 30mV of output voltage deviation
even during ultra-fast load steps, making the MIC38300 an
ideal choice for low-voltage ASICs and other digital ICs.
The MIC38300 features a fully-integrated switching
regulator and LDO combo, operates with input voltages
from 3.0V to 5.5V input, and offers adjustable output
voltages down to 1.0V.
The MIC38300 is offered in the small 28-pin 4mm × 6mm
®
× 0.9mm MLF package and can operate from –40°C to
+125°C.
HELDO®
Features
•
•
•
•
•
•
•
•
•
•
3A peak output current
2.2A continuous operating current
Input voltage range: 3.0V to 5.5V
Adjustable output voltage down to 1.0V
Output noise less than 5mV
Ultra-fast transient performance
Unique switcher plus LDO architecture
Fully-integrated MOSFET switches
Micro-power shutdown
Easy upgrade from LDO as power dissipation becomes
an issue
• Thermal shutdown and current-limit protection
• 4mm × 6mm × 0.9mm MLF package
Applications
•
•
•
•
Point-of-load applications
Networking, server, industrial power
Wireless base-stations
Sensitive RF applications
Datasheets and support documentation are available on
Micrel’s web site at: www.micrel.com.
Typical Application
HELDO is a registered trademark of Micrel, Inc.
MLF and MicroLead Frame are registered trademarks of Amkor Technology, 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
April 10, 2013
Revision 5.0
Micrel, Inc.
MIC38300
Ordering Information
Part Number
Output Current
MIC38300HYHL
3.0A
Voltage
(1)
Junction Temperature Range
Package
–40°C to +125°C
Pb-Free 28-Pin 4mm × 6mm MLF
Adjustable
Note:
1. Other voltages are available. Contact Micrel for details.
Pin Configuration
SWO 1
28 SW
SWO 2
27 SW
SWO 3
26 SW
SWO 4
25 SW
SWO 5
24 SW
SW
6
23 SW
ePAD
7
22 ePAD
AVIN
8
21 PGND
LPF
9
20 PGND
AGND 10
18 EN
12
13
14
15
16
17
LDOOUT
LDOOUT
LDOIN
LDOIN
PVIN
PVIN
FB
19 PGND
11
28-Pin 4mm × 6mm MLF (ML)
(Top View)
Pin Description
Pin Number
MIC38300HYHL
Pin Name
1, 2, 3, 4, 5
SWO
6, 23, 24, 25, 26, 27, 28
SW
7, 22
ePAD
Exposed heat-sink pad. Connect externally to PGND.
8
AVIN
Analog Supply Voltage: Supply for the analog control circuitry. Requires bypass capacitor
to ground. Nominal bypass capacitor is 1µF.
9
LPF
Low Pass Filter: Attach external resistor from SW to increase hysteretic frequency.
10
AGND
11
FB
April 10, 2013
Pin Name
Switch (Output): This is the output of the PFM Switcher.
Switch Node: Attach external resistor from LPF to increase hysteretic frequency.
Analog Ground.
Feedback: Input to the error amplifier. Connect to the external resistor divider network to
set the output voltage.
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Revision 5.0
Micrel, Inc.
MIC38300
Pin Description (Continued)
Pin Number
MIC38300HYHL
Pin Name
Pin Name
12, 13
LDOOUT
LDO Output: Output of voltage regulator. Place capacitor to ground to bypass the output
voltage. Nominal bypass capacitor is 10µF.
14, 15
LDOIN
16, 17
PVIN
18
EN
19, 20, 21
PGND
April 10, 2013
LDO Input: Connect to SW output. Requires a bypass capacitor to ground. Nominal
bypass capacitor is 10µF.
Input Supply Voltage (Input): Requires bypass capacitor to GND. Nominal bypass
capacitor is 10µF.
Enable (Input): Logic low will shut down the device, reducing the quiescent current to less
than 50µA. This pin can also be used as an undervoltage lockout function by connecting a
resistor divider from EN/UVLO pin to VIN and GND. It should be not left open.
Power Ground.
3
Revision 5.0
Micrel, Inc.
MIC38300
Absolute Maximum Ratings(1)
Operating Ratings(2)
Supply Voltage (VIN) ......................................................... 6V
Output Switch Voltage (VSW) ............................................ 6V
LDO Output Voltage (VOUT) .............................................. 6V
Logic Input Voltage (VEN) ................................. –0.3V to VIN
(3)
Power Dissipation .................................. Internally Limited
Storage Temperature (TS) ...................–65°C ≤ TJ ≤ +150°C
(4)
ESD Rating ............................................................... 1.5kV
Supply voltage (VIN) ......................................... 3.0V to 5.5V
Junction Temperature Range ........... –40°C ≤ TJ ≤ +125°C
Enable Input Voltage (VEN) ..................................... 0V to VIN
Package Thermal Resistance
4mm × 6mm MLF-28 (θJA) ................................ 24°C/W
Electrical Characteristics(5)
TA = 25°C with VIN = VEN = 5V; IOUT = 10mA, VOUT = 1.8V. Bold values indicate –40°C ≤ TJ ≤ +125°C, unless noted.
Parameter
Conditions
Min.
3.0
Supply Voltage Range (AVIN, PVIN)
Undervoltage Lockout Threshold
Typ.
Turn-on
UVLO Hysteresis
Max.
Units
5.5
V
2.85
V
100
mV
1
mA
Quiescent Current
IOUT = 0A, Not switching, open loop
Turn-On Time
VOUT to 95% of nominal
200
500
µs
Shutdown Current
VEN = 0V
30
50
µA
Feedback Voltage
±2.5%
1
1.025
V
0.975
Feedback Current
5
0.85
nA
Dropout Voltage (VIN – VOUT)
ILOAD = 2.2A; VOUT = 3V
Current Limit
VFB = 0.9 × VNOM
Output Voltage Load Regulation
VOUT = 1.8V, 10mA to 2.2A
0.3
1
%
Output Voltage Line Regulation
VOUT = 1.8V, VIN from 3.0V to 5.5V
0.35
0.5
%/V
Output Ripple
ILOAD = 1.5A, COUTLDO = 20µF, COUTSW = 20µF
LPF = 25kΩ
3
1.2
5
V
A
2
mV
Over-Temperature Shutdown
150
°C
Over-Temperature Shutdown Hysteresis
15
°C
Enable Input
(6)
Enable Input Threshold
Regulator enable
Enable Hysteresis
0.90
1
1.1
V
20
100
200
mV
0.03
1
µA
Enable Input Current
Notes:
1. Exceeding the absolute maximum rating may damage the device.
2. The device is not guaranteed to function outside its operating rating.
3. The maximum allowable power dissipation of any TA (ambient temperature) is PD(max) = (TJ(max) – TA) / θJA. Exceeding the maximum allowable power
dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown.
4. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5kΩ in series with 100pF.
5. Specification for packaged product only.
6. Enable pin should not be left open.
April 10, 2013
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Revision 5.0
Micrel, Inc.
MIC38300
Typical Characteristics
VIN = 3.3V, VOUT = 1.8V, COUT = 10µF, RLPF = 25kΩ, IOUT = 100mA, unless noted.
Load Regulation
MIC38300 PSRR
90
1.820
2.0
80
1.815
70
1.810
1.8
1.6
60
50
1.800
40
1.795
30
20
1.790
10
1.785
0
10
1.88
100
1k
10k
FREQUENCY (Hz)
100k
Output Voltage
vs. Temperature
1.86
1.84
1.82
1.80
1.78
1.76
1.74
1.72
0.9
VIN = 3.3V
COUT = 10µF
IOUT = 10mA
20 40 60 80
TEMPERATURE (°C)
Dropout Voltage
vs. Load Current
0.8
0.5
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
V = 3.3V
0.4 IN
VOUT = 1.8V
0.2 COUT = 10µF
0
-40
10
60
110 160
TEMPERATURE (°C)
1.0
MIC38300 Efficiency
90
80
70
60
50
40
30
20
10
210
Dropout Voltage
vs. Temperature
2A
1A
VIN = 3.3V
COUT = 20µF
RLPF
0.5 1.0 1.5 2.0 2.5 3.0
LOAD CURRENT (A)
0.5
0.4
VOUT = 4V
COUT = 20µF
20 40 60 80
TEMPERATURE (°C)
5
10mA
1.0
2A
0.8
0.6
0.4 VOUT = 1.8V
0.2 COUT = 10µF
0
012345
INPUT VOLTAGE (V)
Thermal Shutdown
0.6
0.3
April 10, 2013
3.0
0.7
0.4
0
0
0.5 1.0 1.5 2.0 2.5
LOAD CURRENT (A)
0.8
0.6
0.1
1.780
0
VIN = 3.3V
VOUT = 1.8V
COUT = 10µF
0.9
0.7
0.2
1.4
1.2
1.805
Output Voltage
vs. Input Voltage
0
0
VIN = 5V
VOUT = 3.3V
COUT = 10µF
0.5 1.0 1.5 2.0 2.5
LOAD CURRENT (A)
3.0
Current Limit
vs. Input Voltage
5.5
5.3
5.1
4.9
4.7
4.5
4.3
4.1
VOUT = 1V
3.9
COUT = 20µF
3.7
RLPF
3.5
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
INPUT VOLTAGE (V)
Revision 5.0
Micrel, Inc.
MIC38300
Typical Characteristics (Continued)
VIN = 3.3V, VOUT = 1.8V, COUT = 10µF, RLPF = 25kΩ, IOUT = 100mA, unless noted.
1.00
0.95
0.90
VOUT = 1.8V
COUT = 10µF
0.85
0.80
3.0
3.5
4.0
4.5
5.0
INPUT VOLTAGE (V)
Switch Frequency vs.
RLPF Resistance (3.3V-1.8V)
2A
2
1.5
1
10mA
1A
1.5A
0.5
0
10
Switch Frequency vs.
RLPF Resistance (5.0V-2.5V)
500mA
2
1.5
10mA
1
1A
0.5
0
10
100
1000
RLPF RESISTANCE (kohms)
April 10, 2013
VOUT = 1.8V
COUT = 10µF
3.5
4
4.5
5
INPUT VOLTAGE (V)
1.5A
2.5
2A
1A
2
1.5
500mA
1
10mA
0.5
3
2.5
5.0V
2
5.5V
1.5
1
0.5
0
-40 -20 0
20 40 60 80
AMBIENT TEMPERATURE (°C)
6
2A
2
1.5 10mA
500mA
1
1.5A
0.5
100
1000
RLPF RESISTANCE (kohms)
Switch Frequency vs.
RLPF Resistance (5.0V-1.8V)
3
1.5A
2.5
2A
1A
2
1.5
1
10mA
500mA
0.5
0
10
100
1000
RLPF RESISTANCE (kohms)
3.3V
1A
2.5
0
10
5.5
100
1000
RLPF RESISTANCE (kohms)
Max Output Current @ 110°C
Case Temp (1.2V VOUT)
3.5
MAX OUTPUT CURRENT (A)
SWITCH FREQUENCY (MHz)
2.5
10
Max Output Current @ 110°C
Case Temp (1.0V VOUT)
3
2A
20
0
10
100
1000
RLPF RESISTANCE (kohms)
1.5A
30
3
SWITCH FREQUENCY (MHz)
SWITCH FREQUENCY (MHz)
500mA
40
Switch Frequency vs.
RLPF Resistance (5.0V-1.0V)
3
2.5
50
0
3
5.5
3
SWITCH FREQUENCY (MHz)
1.05
60
Switch Frequency vs.
RLPF Resistance (3.3V-1.0V)
SWITCH FREQUENCY (MHz)
1.10
Operating Current
vs. Input Voltage
3.5
MAX OUTPUT CURRENT (A)
1.20
1.15
OPERATING CURRENT (mA)
Enable Threshold
3.3V
3
2.5
5.0V
2
5.5V
1.5
1
0.5
0
-40 -20 0
20 40 60 80
AMBIENT TEMPERATURE (°C)
Revision 5.0
Micrel, Inc.
MIC38300
Typical Characteristics (Continued)
VIN = 3.3V, VOUT = 1.8V, COUT = 10µF, RLPF = 25kΩ, IOUT = 100mA, unless noted.
Max Output Current @ 110°C
Case Temp (1.8V VOUT)
Max Output Current @ 110°C
Case Temp (2.5V VOUT)
5.0V
3
2.5
2
5.5V
1.5
1
0.5
0
-40 -20 0
20 40 60 80
AMBIENT TEMPERATURE (°C)
April 10, 2013
3.5
MAX OUTPUT CURRENT (A)
MAX OUTPUT CURRENT (A)
3.5
3
5.0V
2.5
2
5.5V
1.5
1
0.5
0
-40 -20 0
20 40 60 80
AMBIENT TEMPERATURE (°C)
7
Revision 5.0
Micrel, Inc.
MIC38300
Functional Characteristics
VIN = 3.3V, VOUT = 1.8V, COUT = 10µF, Inductor = 470nH; RLPF = 25kΩ, IOUT = 100mA, unless noted.
April 10, 2013
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Revision 5.0
Micrel, Inc.
MIC38300
Functional Diagram
April 10, 2013
9
Revision 5.0
Micrel, Inc.
MIC38300
EMI Performance
VOUT =1.8V, IOUT = 1.2A.
EMI Test − Horizontal Front
EMI Test − Vertical Front
Additional components to MIC38150 Evaluation Board (Performance similar to MIC38300):
1.
Input Ferrite Bead Inductor. Part number: BLM21AG102SN1D.
2.
0.1µF and 0.01µF ceramic bypass capacitors on PVIN, SW, SWO, and LDOOUT pins.
April 10, 2013
10
Revision 5.0
Micrel, Inc.
MIC38300
Application Information
Enable Input
The MIC38300 features a TTL/CMOS compatible positive
logic enable input for on/off control of the device. High
enables the regulator while low disables the regulator. In
shutdown the regulator consumes very little current (only
a few microamperes of leakage). For simple applications
the enable (EN) can be connected to VIN (IN).
Adjustable Regulator Design
The adjustable MIC38300 output voltage can be
programmed from 1V to 5.0V using a resistor divider from
output to the FB pin. Resistors can be quite large, up to
100kΩ because of the very high input impedance and low
bias current of the sense amplifier. For large value
resistors (>50kΩ) R1 should be bypassed by a small
capacitor (CFF = 0.1µF bypass capacitor) to avoid
instability due to phase lag at the ADJ/SNS input.
Input Capacitor
PVIN provides power to the MOSFETs for the switch
mode regulator section and the gate drivers. Due to the
high switching speeds, a 10µF capacitor is recommended
close to PVIN and the power ground (PGND) pin for
bypassing.
Analog VIN (AVIN) provides power to the analog supply
circuitry. Careful layout should be considered to ensure
high-frequency switching noise caused by PVIN is
reduced before reaching AVIN. A 1µF capacitor as close
to AVIN as possible is recommended.
Output Capacitor
The MIC38300 requires an output capacitor for stable
operation. As a µCap LDO, the MIC38300 can operate
with ceramic output capacitors of 10µF or greater. Values
of greater than 10µF improve transient response and
noise reduction at high frequency. X7R/X5R dielectrictype ceramic capacitors are recommended because of
their superior temperature performance. X7R-type
capacitors change capacitance by 15% over their
operating temperature range and are the most stable
type of ceramic capacitors. Larger output capacitances
can be achieved by placing tantalum or aluminum
electrolytics in parallel with the ceramic capacitor. For
example, a 100µF electrolytic in parallel with a 10µF
ceramic can provide the transient and high frequency
noise performance of a 100µF ceramic at a significantly
lower cost. Specific undershoot/overshoot performance
will depend on both the values and ESR/ESL of the
capacitors.
Figure 1. Adjustable Regulator with Resistors
The output resistor divider values are calculated by
Equation 1:
 R1 
VOUT = 1V 
+ 1
 R2 
Efficiency Considerations
Efficiency is defined as the amount of useful output
power, divided by the amount of power supplied.
V
×I
Efficiency _ % =  OUT OUT
V
×
IN IIN

For less than 5mV noise performance at higher current
loads, 20µF capacitors are recommended at LDOIN and
LDOOUT.
Low Pass Filter Pin
The MIC38300 features a Low Pass Filter (LPF) pin for
adjusting the switcher frequency. By tuning the
frequency, the user can further improve output ripple
without losing efficiency. Adjusting the frequency is
accomplished by connecting a resistor between the LPF
and SW pins. A small value resistor would increase the
frequency while a larger value resistor decreases the
frequency. Recommended RLPF value is 25kΩ. Please
see Typical Characteristics section for more details.
April 10, 2013
Eq. 1

 × 100

Eq. 2
Maintaining high efficiency serves two purposes. It
reduces power dissipation in the power supply, reducing
the need for heat sinks and thermal design
considerations and it reduces consumption of current for
battery-powered applications. Reduced current draw from
a battery increases the devices operating time and is
critical in handheld devices.
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Revision 5.0
Micrel, Inc.
MIC38300
There are two types of losses in switching converters; DC
losses and switching losses. DC losses are simply the
2
power dissipation of I R. Power is dissipated in the high
side switch during the on cycle. Power loss is equal to the
high-side MOSFET RDSON multiplied by the switch
current. During the off cycle, the low side N-channel
MOSFET conducts, also dissipating power. Device
operating current also reduces efficiency. The product of
the quiescent (operating) current and the supply voltage
is another DC loss.
If the current through the current sense of HELDO2 is
less than the current through the current sense of
HELDO1, the inverting pin will be at a higher voltage than
the non-inverting pin and the op-amp will drive the FB of
HELDO2 low. The low voltage sensed on HELDO2 FB
pin will drive the output up until the output voltage of
HELDO2 matches the output voltage of HELDO1. Since
VOUT will remain constant and both HELDO VOUT
terminals and sense resistances are matched, the output
currents will be shared equally.
Over 100mA, efficiency loss is dominated by MOSFET
RDSON and inductor losses. Higher input supply voltages
will increase the gate-to-source threshold on the internal
MOSFETs, reducing the internal RDDSON. This improves
efficiency by reducing DC losses in the device. All but the
inductor losses are inherent to the device. In which case,
inductor selection becomes increasingly critical in
efficiency calculations. As the inductors are reduced in
size, the DC resistance (DCR) can become quite
significant. The DCR losses can be calculated as in
Equation 3:
2
L_PD = IOUT × DCR
Eq. 3
From that, the loss in efficiency due to inductor resistance
can be calculated as in Equation 4:
 

VOUT × IOUT
 × 100
Efficiency _ Loss = 1 − 
  VOUT × IOUT + L _ PD 

 
Eq. 4
Efficiency loss due to DCR is minimal at light loads and
gains significance as the load is increased. Inductor
selection becomes a trade-off between efficiency and
size in this case.
Current-Sharing Circuit
Figure 2 allows two MIC38300 HELDO regulators to
share the load current equally. HELDO1 senses the
output voltage at the load, on the other side of a current
sense resistor. As the load changes, a voltage equal to
the output voltage, plus the load current times the sense
resistor, is developed at the VOUT terminal of HELDO1.
The op-amp (MIC7300) inverting pin senses this voltage
and compares it to the voltage on the VOUT terminal of
HELDO2.
April 10, 2013
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Revision 5.0
Micrel, Inc.
MIC38300
Figure 2. Current-Sharing Circuit for 6A Output
April 10, 2013
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Revision 5.0
Micrel, Inc.
MIC38300
Package Information(1)
28-Pin 4mm × 4mm MLF (ML)
Note:
1. Package information is correct as of the publication date. For updates and most current information, go to www.micrel.com.
April 10, 2013
14
Revision 5.0
Micrel, Inc.
MIC38300
Recommended Landing Pattern
LP # HMLF46T-28LD-LP-1
All units are in mm
Tolerance ±0.05, if not noted
Red circles indicate Thermal Vias. Size should be .300mm − .350mm in diameter and it should be connected to
GND plane for maximum thermal performance.
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com
Micrel makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this data sheet. This
information is not intended as a warranty and Micrel does not assume responsibility for its use. Micrel reserves the right to change circuitry,
specifications and descriptions at any time without notice. No license, whether express, implied, arising by estoppel or otherwise, to any intellectual
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© 2007 Micrel, Incorporated.
April 10, 2013
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Revision 5.0