MIC2810
Digital Power Management IC
2MHz, 600mA DC/DC w/Dual
300mA/300mA Low V
IN
LDOs
LOWQ is a registered trademark of Micrel, Inc.
MLF and MicroLeadFrame 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 2007 1 M9999-041107-B
General Description
The MIC2810 is a high performance power management
IC, integrating a 2MHz DC/DC switcher with two 300mA
LDOs. The MIC2810 features a LOWQ
®
mode, reducing
the total current draw while in this mode to less than 30µA.
In LOWQ
®
mode, the output noise of the DC/DC converter
is 53µV
RMS
, significantly lower than other converters that
use a PFM light load mode that can interfere with sensitive
RF circuitry.
The MIC2810 is a µCap design, operating with very small
ceramic output capacitors and inductors for stability,
therefore, reducing required board space and component
cost. It is available with fixed output voltages in a 16-pin
3mm x 3mm MLF
®
leadless package.
Data sheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
Features
• 2MHz DC/DC converter and two LDOs
• Integrated power-on reset (OR function for all outputs)
– Adjustable delay time
• LOWQ
®
mode
– 30µA Total I
Q
when in LOWQ
®
mode
• Tiny 16-pin 3mm x 3mm MLF
®
package
• Thermal shutdown protection
• Current limit protection
DC/DC Converter
• 2.7V to 5.5V input voltage range
• Output current to 600mA in PWM mode
• LOWQ
®
Mode: NO NOISE light load mode
– 53µV
RMS
Output noise in LOWQ
®
mode
• 2MHz PWM operation in normal mode
LDOs
• LDO1
– 1.65V to 5.5V input voltage range
– 300mA Output current
– Output voltage down to 0.8V
• LDO2
– 2.7V to 5.5V input voltage range
– 300mA Output current
– Output voltage down to 0.8V
Applications
• Mobile phones
• PDAs
• GPS receivers
• Digital still cameras
• Portable media players
Typical Application
LDOVIN
VIN1 SW
LDO1
LDO2
POR
CSET
LOWQ
EN2
BIAS
EN1
MIC2810-xxxYML
Baseband
Memory/DSP
PGND SGND
V
IN
2.7V to 5.5V
4.7µF
2.2µF
ceramic
2.2µF
ceramic
0.01µF0.1µF
2.2µF
V
OUT
2.2µH
GNDGND
EN
VIN2
10
20
30
40
50
60
70
80
90
0 100 200 300 400 500 600
OUTPUT CURRENT (mA)
1.2VOUT Efficiency
V
IN
=3.6V
V
IN
=3V
V
IN
=4.2V
Micrel, Inc. MIC2810
April 2007
2 M9999-041107-B
Ordering Information
Part number Manufacturing
Part Number
Voltage* Junction
Temperature Range
Package
MIC2810-1.2/1.2/2.8YML MIC2810-44MYML 1.2V/1.2V/2.8V –40°C to +125°C 16-Pin 3x3 MLF
®
MIC2810-1.2/1.8/2.6YML MIC2810-4GKYML 1.2V/1.8V/2.6V –40°C to +125°C 16-Pin 3x3 MLF
®
MIC2810-1.2/1.8/2.8YML MIC2810-4GMYML 1.2V/1.8V/2.8V –40°C to +125°C 16-Pin 3x3 MLF
®
MIC2810-1.2/1.8/3.0YML MIC2810-4GPYML 1.2V/1.8V/3.0V –40°C to +125°C 16-Pin 3x3 MLF
®
MIC2810-1.2/1.8/3.3YML MIC2810-4GSYML 1.2V/1.8V/3.3V –40°C to +125°C 16-Pin 3x3 MLF
®
MIC2810-1.2/2.7/3.3YML MIC2810-4LSYML 1.2V/2.7V/3.3V –40°C to +125°C 16-Pin 3x3 MLF
®
MIC2810-1.2/2.8/3.3YML MIC2810-4MSYML 1.2V/2.8V/3.3V –40°C to +125°C 16-Pin 3x3 MLF
®
Notes:
Other voltage options available. Please contact Micrel for details.
DC/DC – Fixed Output Voltages.
LDO1 – Output Voltage Range of 0.8V to 3.6V.
LDO2 – Output Voltage Range of 0.8V to 3.6V.
* Refers to nominal output voltage of DC/DC, LDO1, and LDO2 respectively.
Micrel, Inc. MIC2810
April 2007
3 M9999-041107-B
Pin Configuration
16-Pin 3mm x 3mm MLF
®
(ML)
Pin Description
Pin Number Pin Name Pin Function
1 /LOWQ
LOWQ Mode. Active Low Input. Logic High = Full Power (Normal) Mode;
Logic Low = LOWQ Mode; Do not leave floating.
2 BIAS
Internal circuit bias supply. It must be de-coupled to signal ground with a 0.1µF
capacitor and should not be loaded.
3 SGND Signal ground.
4 PGND Power ground.
5 SW Switch: Internal power MOSFET output switches.
6 VIN
Supply Input – DC/DC and other circuitry shared with LDO1 and LDO2. Must be
connected to PIN 7.
7 VIN2 Supply Input – LDO2. Must be connected to PIN 6.
8 LDO2 Output of LDO2
9 LDO LDO Output: Connect to V
OUT
of the DC/DC for LOWQ mode operation.
10 VIN1 Supply Input – LDO1.
11 LDO1 Output of LDO1
12 POR
Power-On Reset Output: Open-drain output. Active low indicates an output
undervoltage condition on either one of the three regulated outputs.
13 CSET
Delay Set Input: Connect external capacitor to GND to set the internal delay for the
POR output. When left open, there is minimum delay. This pin cannot be grounded.
14 EN1
Enable Input (LDO 1). Active High Input. Logic High = On; Logic Low = Off; Do not
leave floating
15 EN
Enable Input (DC/DC). Active High Input. Logic High = On; Logic Low = Off; Do not
leave floating.
16 EN2
Enable Input (LDO 2). Active High Input. Logic High = On; Logic Low = Off; Do not
leave floating
Micrel, Inc. MIC2810
April 2007
4 M9999-041107-B
Absolute Maximum Ratings(1)
Supply Voltage (V
IN
, V
IN1
, V
IN2
)............................... 0V to 6V
Enable Input Voltage (V
EN
, V
EN1
, V
EN2
)................... 0V to V
IN
Power Dissipation .................................. Internally Limited
(3)
Lead Temperature (soldering, 10 sec.)...................... 260°C
Storage Temperature (T
s
) .........................–65°C to +150°C
ESD Rating
(4)
.................................................................. 2kV
Operating Ratings(2)
Supply Voltage (V
IN
, V
IN2
)................................. 2.7V to 5.5V
Supply Voltage (V
IN1
)...................................... 1.65V to 5.5V
Enable Input Voltage (V
EN
, V
EN1
, V
EN2
)................... 0V to V
IN
Junction Temperature (T
J
) ........................ –40°C to +125°C
Junction Thermal Resistance
MLF-16 (
JA
) ......................................................56°C/W
Electrical Characteristics(5)
V
IN
= V
IN1
= V
IN2
= EN1 = EN2 = EN = /LOWQ = V
OUT
(6)
+ 1V; C
OUTDC/DC
= 2.2µF, C
LDO1
= C
LDO2
= 2.2µF; I
OUTDC/DC
= 100mA;
I
OUTLDO1
= I
OUTLDO2
= 100µA; T
J
= 25°C, bold values indicate –40°C < T
J
< +125°C; unless noted.
Parameter Conditions Min Typ Max Units
UVLO Threshold Rising input voltage during turn-on 2.45 2.55 2.65 V
UVLO Hysteresis 100 mV
Ground Pin Current
V
FB
= GND (not switching);
LDO1 or LDO2 (EN = GND; EN1 or EN2 = GND)
800
55
1100
85
95
µA
µA
µA
Ground Pin Current in
Shutdown
EN = EN1 = EN2 = 0V 0.2 5 µA
Ground Pin Current
(LOWQ
®
mode)
I
DC/DC
< I
LDO1
< I
LDO2
< 10mA (/LOWQ = GND)
LDO1 or LDO2 (EN = GND; EN1 or EN2 = GND);
I
OUT
< 10mA (/LOWQ = GND)
38
20
60
80
70
µA
µA
µA
Over-temperature Shutdown 160 °C
Over-temperature Shutdown
Hysteresis
23
°C
Enable Inputs (EN; EN1; EN2; /LOWQ )
Logic Low 0.2 V Enable Input Voltage
Logic High 1.0 V
V
IL
< 0.2V 0.1 1 µA Enable Input Current
V
IH
> 1.0V 0.1 1 µA
Turn-on Time
Turn-on Time
(LDO1 and LDO2)
240 500 µs
Turn-on Time (DC/DC) (/LOWQ = V
IN
; I
LOAD
= 300mA); (/LOWQ = GND; I
LOAD
=
10mA)
83 350 µs
POR Output
Low Threshold, % of nominal (V
DC/DC
or V
LDO1
or V
LDO2
) (Flag
ON) 90 91 %
VTH
High Threshold, % of nominal (V
DC/DC
AND V
LDO1
AND
V
LDO2
) (Flag OFF) 96 99 %
VOL POR Output Logic Low Voltage; IL = 250µA 10 100 mV
IPOR Flag Leakage Current, Flag OFF 0.01 1 µA
SET INPUT
SET Pin Current Source VSET = 0V 0.75 1.25 1.75 µA
SET Pin Threshold Voltage POR = High 1.25 V
Micrel, Inc. MIC2810
April 2007
5 M9999-041107-B
Electrical Characteristics - DC/DC Converter
V
IN
= V
OUTDC/DC
+ 1; EN = V
IN
; EN2 = EN1 = GND; I
OUTDC/DC
= 100mA ;L = 2.2µH; C
OUTDC/DC
= 2.2µF; T
J
= 25°C,
bold values indicate –40°C to + 125°C; unless noted.
Parameter Conditions Min Typ Max Units
LOWQ = High (Full Power Mode)
Fixed Output Voltages Nominal V
OUT
tolerance
–2
–3
+2
+3
%
%
Output Voltage Line Regulation V
OUT
> 2.4V; V
IN
= V
OUT
+ 300mV to 5.5V, I
LOAD
= 100mA
V
OUT
< 2.4V; V
IN
= 2.7V to 5.5V, I
LOAD
= 100mA
0.2 %/V
Output Voltage Load Regulation 20mA < I
LOAD
< 600mA 0.1 %
Maximum Duty Cycle V
FB
≤ 0.4V 100 %
PWM Switch ON-Resistance
I
SW
= 150mA V
FB
= 0.7V
FB_NOM
PMOS
I
SW
= -150mA V
FB
= 1.1V
FB_NOM
NMOS
0.5
0.6
Oscillator Frequency 1.8 2 2.2 MHz
Current Limit in PWM Mode V
FB
= 0.9*V
NOM
0.75 1 1.6 A
LOWQ = Low (Light Load Mode)
Variation from nominal V
OUT
–2 +2 % Output Voltage Accuracy
Variation from nominal V
OUT
; –40°C to +125°C –3 +3 %
Line Regulation V
IN
= V
OUT
+ 1V to 5.5V; I
OUT
= 100µA
0.02 0.3
0.6
%/V
%/V
Load Regulation I
OUT
= 100µA to 50mA 0.4 1.5 %
Ripple Rejection f = up to 1kHz 45 dB
Current Limit V
OUT
= 0V 80 120 220 mA
Output Voltage Noise 10Hz to 100KHz 53 µV
RMS
Micrel, Inc. MIC2810
April 2007
6 M9999-041107-B
Electrical Characteristics – LDO1/LDO2
V
IN1
= V
IN2
= V
OUTLDO1
+ 1.0V or V
IN1
= V
IN2
= V
OUTLDO2
+ 1.0V; EN = GND; EN1 = EN2 = V
IN1
= V
IN2
; C
LDO1
= C
LDO2
= 2.2µF;
I
OUTLDO1
= 100µA; T
J
= 25°C, bold values indicate –40°C< T
J
< +125°C; unless noted.
Parameter Conditions Min Typ Max Units
LOWQ = High (Full Power Mode)
Variation from nominal V
OUT
–2 +2 % Output Voltage Accuracy
Variation from nominal V
OUT
; –40°C to +125°C –3 +3 %
Line Regulation V
IN
= V
OUT
+1V to 5.5V
0.02 0.3
0.6
%/V
Load Regulation I
OUT
= 100µA to 150mA
I
OUT
= 100µA to 200mA
I
OUT
= 100µA to 300mA
0.20
0.25
0.40
1.5
%
%
%
Dropout Voltage
I
OUT
= 150mA
I
OUT
= 200mA
I
OUT
= 300mA
70
94
142
300
mV
mV
mV
Ripple Rejection f = up to 1kHz 35 dB
Current Limit V
OUT
= 0V 400 600 850 mA
Output Voltage Noise 10Hz to 100kHz 91 µV
RMS
LOWQ = Low (Light Load Mode)
Variation from nominal V
OUT
–3 +3 % Output Voltage Accuracy
Variation from nominal V
OUT
; –40°C to +125°C –4 +4 %
Line Regulation V
IN
= V
OUT
+1V to 5.5V
0.02 0.3
0.6
%/V
Load Regulation I
OUT
= 100µA to 10mA 0.2 1.0 %
Dropout Voltage I
OUT
= 10mA 22 35
50
mV
mV
Ripple Rejection f = up to 1kHz 35 dB
Current Limit V
IN
= 2.7V; V
OUT
= 0V 50 85 125 mA
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 T
A
(ambient temperature) is P
D(max)
= (T
J(max)
– T
A
) / θ
JA
. 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, 1.5k in series with 100pF.
5. Specification for packaged product only.
Micrel, Inc. MIC2810
April 2007
7 M9999-041107-B
Typical Characteristics ― DC/DC Normal Mode (/LOWQ = VIN)
10
20
30
40
50
60
70
80
90
0 100 200 300 400 500 600
OUTPUT CURRENT (mA)
1.2VOUT Efficiency
V
IN
=3.6V
V
IN
=3V
V
IN
=4.2V
1.7
1.8
1.9
2.0
2.1
2.2
2.3
2.4
2.7
INPUT CURRENT (V)
Switching Frequency
vs. Input Voltage
3.1 3.5 3.9 4.3 4.7 5.1 5.5
C
OUT
= 2.2µF
I
OUT
= 300mA
L = 2.2µH
/LowQ = V
IN
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2.0
2.1
2.2
2.3
2.4
Switching Frequency
vs. Temperature
-40 -20 0 40 60 80 100
TEMPERATURE (°C)
20 120
V
IN
= 3.6V
I
OUT
= 400mA
/LowQ = V
IN
1.18
1.19
1.20
1.21
1.22
0 100 200 300 400 500 600
OUTPUT CURRENT (mA)
Load Regulation
C
OUT
= 2.2µF
V
IN
= 3.6V
L = 2.2µH
/LowQ = V
IN
1.192
1.194
1.196
1.198
1.200
2.7
INPUT VOLTAGE (V)
C
OUT
= 2.2µF
I
OUT
= 300mA
L = 2.2µH
/LowQ = V
IN
3.1 3.5 3.9 4.3 4.7 5.1 5.5
Line Regulation
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.7
INPUT VOLTAGE (V)
Current Limit
vs. Input Voltage
3.1 3.5 3.9 4.3 4.7 5.1 5.5
/LowQ = V
IN
Micrel, Inc. MIC2810
April 2007
8 M9999-041107-B
Typical Characteristics ― DC/DC LOWQ Mode (/LOWQ = GND)
0
10
20
30
40
50
60
70
80
0.01 0.1 1 10 100 1000
FREQUENCY (kHz)
Power Supply
Rejection Ratio
V
IN
= 3.6V
V
OUT
= 1.2V
C
OUT
= 2.2µF
I
OUT
= 5mA
/LowQ = GND
1.16
1.17
1.18
1.19
1.20
1.21
1.22
1.23
1.24
0 1020304050607080
OUTPUT CURRENT (mA)
Load Regulation
C
OUT
= 2.2µF
V
IN
= 3.6V
/LowQ = GND
1.10
1.15
1.20
1.25
1.30
2.7
INPUT VOLTAGE (V)
Line Regulation
3.1 3.5 3.9 4.3 4.7 5.1 5.5
C
OUT
= 2.2µF
V
IN
= 3.6V
I
OUT
= 20mA
/LowQ = GND
20
60
100
140
180
220
260
300
340
380
2.7
INPUT VOLTAGE (V)
Current Limit
vs. Input Voltage
3.1 3.5 3.9 4.3 4.7 5.1 5.5
/LowQ = GND
0.001
0.01
0.1
1
10
Output Noise
Spectral Density
1
FREQUENCY (kHz)
0.10.01 10 100 1,000
V
IN
= 4.2V
V
OUT
= 1.2V
C
OUT
= 2.2µF
/LowQ = GND
10,000
Micrel, Inc. MIC2810
April 2007
9 M9999-041107-B
Typical Characteristics ― LDO1/LDO2
0
10
20
30
40
50
60
70
80
0.01 0.1 1 10 100 1000
FREQUENCY (kHz)
Power Supply Rejection Ratio
LDO1[LOWQ Mode]
V
IN
= 3.6V
V
OUT
= 1.2V
C
OUT
= 2.2µF
I
OUT
= 25mA
/LowQ = GND
0
10
20
30
40
50
60
70
0.01 0.1 1 10 100 1000
FREQUENCY (kHz)
Power Supply Rejection Ratio
LDO1[Normal Mode]
V
IN
= 3.6V
V
OUT
= 1.2V
C
OUT
= 2.2µF
I
OUT
= 100mA
/LowQ = V
IN
1.6
1.7
1.8
1.9
2.0
2.7
INPUT VOLTAGE (V)
LDO1 Line Regulation
3.1 3.5 3.9 4.3 4.7 5.1 5.5
C
OUT
= 2.2µF
V
IN
= 3.6V
I
OUT
= 150mA
/LowQ = V
IN
0
10
20
30
40
50
60
70
80
90
0.01 0.1 1 10 100 1000
FREQUENCY (kHz)
Power Supply Rejection Ratio
LDO2[LOWQ Mode]
V
IN
= 3.6V
V
OUT
= 2.8V
C
OUT
= 2.2µF
I
OUT
= 25mA
/LowQ = GND
0
10
20
30
40
50
60
70
80
0.01 0.1 1 10 100 1000
FREQUENCY (kHz)
Power Supply Rejection Ratio
LDO2[Normal Mode]
V
IN
= 3.6V
V
OUT
= 2.8V
C
OUT
= 2.2µF
I
OUT
= 100mA
/LowQ = V
IN
2.70
2.75
2.80
2.85
0 50 100 150 200 250 300
OUTPUT CURRENT (mA)
LDO2 Load Regulation
C
OUT
= 2.2µF
V
IN
= 3.6V
/LowQ = V
IN
55
60
65
70
75
80
0 50 100 150 200 250 300
OUTPUT CURRENT (mA)
LDO2 Ground Current
vs. Output Current
VIN = 3.6V
VOUT = 2.8V
/LowQ = VIN
30
40
50
60
70
80
LDO2 Ground Current
vs. Temperature
-40 -20 0 40 60 80 100
TEMPERATURE (°C)
20 120
VIN = 3.6V
IOUT = 200mA
/LowQ = VIN
0
20
40
60
80
100
120
140
0 50 100 150 200 250 300
OUTPUT CURRENT (mA)
LDO2 Dropout Voltage
vs. Output Current
V
OUT
= 2.8V
/LowQ = V
IN
60
70
80
90
100
110
LDO2 Dropout Voltage
vs. Temperature
-40 -20 0 40 60 80 100
TEMPERATURE (°C)
20 120
VOUT = 2.8V
IOUT = 200mA
/LowQ = VIN
0.001
0.01
0.1
1
10
LDO2 Output Noise
Spectral Density
1
FREQUENCY (kHz)
0.10.01 10 100 1,000
VIN = 4.2V
VOUT = 2.8V
COUT = 2.2µF
/LowQ = VIN
10,000
Micrel, Inc. MIC2810
April 2007
10 M9999-041107-B
Functional Characteristics
LDO2[LOWQ Mode] Load Transient
Time (100µs/div)
VIN = 3.6V
VOUT = 2.8V
COUT = 2.2µF
/LowQ = GND
AC Coupled
(50mV/div)
Output Volta
g
e
DC Coupled
(20mA/div)
Output Current
45mA
1mA
LDO2[Normal Mode] Load Transient
Time (40µs/div)
V
IN
= 3.6V
V
OUT
= 2.8V
C
OUT
= 2.2µF
/LowQ = V
IN
AC Coupled
(50mV/div)
Output Voltage
DC Coupled
(100mA/div)
Output Current
200mA
10mA
Time (40µs/div)
V
IN
= 3.6V
V
OUT
= 1.2V
C
OUT
= 2.2µF
/LowQ = GND
AC Coupled
(20mV/div)
Output Volta
g
e
DC Coupled
(20mA/div)
Output Current
50mA
1mA
DC/DC
[LOWQ Mode]
Load Transient
Time (20µs/div)
V
IN
= 3.6V
V
OUT
= 1.2V
C
OUT
= 2.2µF
/LowQ = GND
I
OUT
= 20mA
DC Coupled
(2V/div)
Enable Voltage
DC Coupled
(500mV/div)
Output Voltage
DC/DC
[LOWQ Mode]
Start-Up Waveforms
Micrel, Inc. MIC2810
April 2007
11 M9999-041107-B
Functional Characteristics (cont.)
DC/DC PWM Waveforms
Time (400ns/div)
V
IN
= 3.6V
V
OUT
= 1.2V
C
OUT
= 2.2µF
L = 2.2µH
/LowQ = V
IN
I
OUT
= 300mA
AC Coupled
(20mV/div)
Output Voltage
DC Coupled
(200mA/div)
Inductor Current
DC Coupled
(2V/div)
Switch Voltage
DC/DC Load Transient
Time (20µs/div)
V
IN
= 3.6V
V
OUT
= 1.2V
C
OUT
= 2.2µF
L = 2.2µH
/LowQ = V
IN
AC Coupled
(50mV/div)
Output Voltage
DC Coupled
(200mA/div)
Output Current
10mA
300mA
DC/DC Start-Up Waveforms
Time (20µs/div)
V
IN
= 3.6V
V
OUT
= 1.2V
C
OUT
= 2.2µF
L = 2.2µH
/LowQ = V
IN
I
OUT
= 300mA
DC Coupled
(2V/div)
Enable Volta
g
e
DC Coupled
(500mV/div)
Output Voltage
Micrel, Inc. MIC2810
April 2007
12 M9999-041107-B
Functional Diagram
MIC2810 Block Diagram
Micrel, Inc. MIC2810
April 2007
13 M9999-041107-B
Device Functional Description
The MIC2810 is a power management IC with a single
integrated step-down regulator and two low dropout
regulators. LDO1 and LDO2 are 300mA low dropout
regulators supplied from the input voltage pins. The
step-down regulator is a 600mA PWM power supply. All
three regulators utilize a /LOWQ light load mode to
maximize battery efficiency under light load conditions.
This is achieved with a /LOWQ control pin that when
pulled low shuts down all the biasing and drive current
for the PWM regulator, along with reducing the current
limit of the two independent LDOs. When the /LOWQ pin
is pulled low, the MIC2810 draws only 30µA of operating
current. This mode allows the output to be regulated
through the LDO output which is capable of providing
60mA of output current. This method has the advantage
of producing a clean, low current, ultra-low noise output
in /LOWQ mode. During /LOWQ mode, the SW node
becomes high impedance, blocking current flow. Other
methods of reducing quiescent current, such as pulse
frequency modulation (PFM) or bursting techniques
create large amplitude and low frequency ripple voltages
that can be detrimental to system operation.
When more than 60mA is required, the /LOWQ pin can
be forced high, causing the MIC2810 to enter PWM
mode. In this case, the LDO output makes a "hand-off"
to the PWM regulator with virtually no variation in output
voltage. The LDO output then turns off allowing up to
600mA of current to be efficiently supplied through the
PWM output to the load.
Pin Functional Description
VIN/VIN1/VIN2
Three input voltage pins provide power to the switch
mode regulator, LDO1, and LDO2. VIN provides power
to the control circuitry of the DC/DC converter and
voltage reference circuitry shared by all the regulators in
the MIC2810. LDO1’s input voltage (VIN1) can go down
to 1.65V but LDO2 and the DC/DC converter input
voltages are limited to 2.7V minimum.
For the switch mode regulator VIN provides power to the
MOSFET along with current limiting sense circuitry. Due
to the high switching speeds, a 4.7µF capacitor is
recommended close to VIN and the power ground
(PGND) pin for bypassing. Please refer to the PCB
layout section for an example of an appropriate circuit
layout.
LDO
The LDO pin is the output of the linear regulator and
should be connected to the output of the step-down
PWM regulator. In /LOWQ mode (/LOWQ <0.2V), the
LDO provides the output voltage of the DC/DC regulator.
LDO1
Regulated output voltage of LDO1. Power is provided by
VIN1. Recommended output capacitance is 2.2µF.
LDO2
Regulated output voltage of LDO2. Power is provided by
VIN2. Recommended output capacitance is 2.2µF.
EN/EN1/EN2
All enable inputs are active high, requiring 1.0V for
guaranteed operation. EN provides logic control for the
DC/DC regulator. EN2 provides logic control for LDO2,
and EN1 provides logic control for LDO1. The enable
inputs are CMOS logic and cannot be left floating.
The enable pins provide logic level control of the
specified outputs. When all enable pins are in the off
state, supply current of the device is greatly reduced
(typically <1µA). When the DC/DC regulator is in the off
state, the output drive is placed in a "tri-stated" condition,
where both the high side P-channel MOSFET and the
low-side N-channel are in an “off” or non-conducting
state. Do not drive any of the enable pins above the
supply voltage.
Power-On Reset (POR)
The power-on reset output is an open-drain N-Channel
device, requiring a pull-up resistor to either the input
voltage or output voltage for proper voltage levels. The
POR output has a delay time that is programmable with
a capacitor from the CSET pin to ground. The delay time
can be programmed to be as long as 1 second.
/LOWQ
The /LOWQ pin provides a logic level control between
the internal PWM switching regulator mode, and the low
noise linear regulator mode. With /LOWQ pulled low
(0.2V), quiescent current of the device is greatly
reduced by switching to a low noise linear regulator
mode that has a typical supply current of 38µA. In linear
(LDO) mode the output can deliver 60mA of current to
the output. By placing /LOWQ high (1V), the device
transitions into a constant frequency PWM step-down
regulator mode. This allows the device the ability to
efficiently deliver up to 600mA of output current at the
same output voltage.
/LOWQ mode also limits the output load of both LDO1
and LDO2 to <50mA.
BIAS
The BIAS pin supplies the power to the internal control
and reference circuitry. The bias is powered from VIN
through an internal 6 resistor. A small 0.1µF capacitor
is recommended for bypassing.
Micrel, Inc. MIC2810
April 2007
14 M9999-041107-B
SW
The switch (SW) pin connects directly to the inductor
and provides the switching current necessary to operate
in PWM mode. Due to the high speed switching on this
pin, the switch node should be routed away from
sensitive nodes.
PGND
Power ground (PGND) is the ground path for the high
current PWM mode. The current loop for the power
ground should be as small as possible.
SGND
Signal ground (SGND) is the ground path for the biasing
and control circuitry. The current loop for the signal
ground should be as small as possible.
CSET
The CSET pin is a current source output that charges a
capacitor that sets the delay time for the power-on reset
output from low to high. The delay for POR high to low
(detecting an undervoltage on any of the outputs) is
always minimal. The current source of 1.25µA charges a
capacitor up from 0V. When the capacitor reaches
1.25V, the output of the POR is allowed to go high. The
delay time in microseconds is equal to the Cset in
picofarads.
POR Delay (µs) = CSET (pF)
Component Selection
Output Capacitor
LDO1 and LDO2 outputs require a 2.2µF ceramic output
capacitor for stability. The DC/DC switch mode regulator
also requires a 2.2µF ceramic output capacitor to be
stable. All output capacitor values can be increased to
improve transient response, but performance has been
optimized for a 2.2µF ceramic on the LDOs and the
DC/DC regulator. X7R/X5R dielectric-type ceramic
capacitors are recommended because of their
temperature performance. X5R/X7R-type capacitors
change capacitance by 15% over their operating
temperature range and are the most stable type of
ceramic capacitors. Z5U and Y5V dielectric capacitors
change value by as much as 50% to 60% respectively
over their operating temperature ranges.
Input Capacitor
A minimum 1µF ceramic, 4.7µF recommended, should
be placed as close as possible to the VIN pin for optimal
bypassing. X5R or X7R dielectrics are recommended for
the input capacitor. Y5V dielectrics lose most of their
capacitance over temperature and are therefore, not
recommended. A minimum 1µF is recommended close
to the VIN and PGND pins for high frequency filtering.
Smaller case size capacitors are recommended due to
their lower ESR and ESL. Please refer to the PCB layout
section for an example of an appropriate circuit layout.
Inductor Selection
The MIC2810 is designed for use with a 2.2µH inductor.
Proper selection should ensure the inductor can handle
the maximum average and peak currents required by the
load. Maximum current ratings of the inductor are
generally given in two methods; permissible DC current
and saturation current. Permissible DC current can be
rated either for a 40°C temperature rise or a 10% to 20%
loss in inductance. Ensure that the inductor selected can
handle the maximum operating current. When saturation
current is specified, make sure that there is enough
margin that the peak current will not saturate the
inductor. Peak inductor current can be calculated as
follows:
Lf2
V
V
1V
II IN
OUT
OUT
OUTPK ××
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛−
+=
I
PK
: Peak Inductor Current
I
OUT
: Output/Load Current
V
IN
: Input Voltage
V
OUT
: Output Voltage
f: Switching Frequency of PWM Regulator
L: Inductor Value
Micrel, Inc. MIC2810
April 2007
15 M9999-041107-B
PCB Layout
Vin
C7 VIN
J1
L1 LD02
J5
C6
SW
VIN2
PGND LDO
BIAS
EN1
LDO1
LDO2
VIN1
EN
EN2
SGND
/LowQ
VIN
CSET
POR
Vo
Vin Vin
Vo
GND
J2
C1
GND
J7
VO
J6
LD0
J3
LD01
J4
POR
J8
EN
J9
EN2
J11
/LowQ
J12
JP1 C3
R1
C4
R3
R4
R5 C5
1
2
56
12
87
49
10
11
3
13141516
C2
Vin
EN1
J10
R2
Layout Schematic
Micrel, Inc. MIC2810
April 2007
16 M9999-041107-B
Top Layer
Micrel, Inc. MIC2810
April 2007
17 M9999-041107-B
Bottom Layer
Micrel, Inc. MIC2810
April 2007
18 M9999-041107-B
Package Information
16-Pin 3mm x 3mm MLF
®
(ML)
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
The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its
use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product
can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant
into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A
Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully
indemnify Micrel for any damages resulting from such use or sale.
© 2006 Micrel, Incorporated.
