MIC2800
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
September 2007
M9999-090507-C
General Description
The MIC2800 is a high performance power management
IC, giving three output voltages with maximum efficiency.
Integrating a 2MHz DC/DC converter with an LDO post
regulator, the MIC2800 gives two high efficiency outputs
with a second, 300mA LDO for maximum flexibility. The
MIC2800 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 to DC converter
is 75µV
RMS
, significantly lower than other converters which
use a PFM light load mode that can interfere with sensitive
RF circuitry.
The DC to DC converter uses small values of L and C to
reduce board space but still retains efficiencies over 90%
at load currents up to 600mA.
The MIC2800 is a µCap design, operating with very small
ceramic output capacitors and inductors for stability,
reducing required board space and component cost and it
is available in fixed output voltages in the 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
• 2.7V to 5.5V input voltage range
• 2MHz DC/DC converter and two stand-alone LDOs
– LDO1: Low input voltage is powered directly from
DC/DC converter for highest efficiency
• 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
DC to DC Converter
• Output current to 600mA in PWM mode
• LOWQ
®
Mode: NO NOISE Light load mode
– 75µV
RMS
output noise in LOWQ
®
mode
• 2MHz PWM operation in normal mode
• >90% efficiency
LDOs
• LDO1 input voltage directly connected to DC/DC
converter output voltage for maximum efficiency
– Ideal for 1.8V to 1.5V conversion
– 300mA output current from 1.8V input
– Output voltage down to 0.8V
• LDO2 – 300mA output current capable
• Thermal Shutdown Protection
• Current Limit Protection
Applications
• Mobile phones
• PDAs
• GPS receivers
• Digital still cameras
• Portable media players
Typical Application
LDOVIN
VIN SW
FB
LDO1
LDO2
POR
C
SET
LOWQ
EN2
C
BYP
C
BIAS
EN1
MIC2800-xxxYML
Baseband
Memory/DSP
PGND SGND
V
IN
2.7V to 5.5V
4.7µF/
6.3V
C
BYP
0.01µF
C
OUT2
2.2µF
ceramic
C
OUT1
2.2µF
ceramic
C
SET
0.01µF
C
BIAS
0.1µF
2.2µF
ceramic
V
OUT
2.2µH
GNDGND
100 200 300 400 500 600
OUTPUT CURRENT (mA)
50
55
60
65
70
75
80
85
90
95
100
DC/DC 1.8V
OUT
Efficiency
0
3V 3.6V
4.2V
L = 2.2µH
C
OUT
= 2.2µF
/LowQ = V
IN
Micrel, Inc. MIC2800
September 2007
2 M9999-090507-C
Ordering Information
Part number Manufacturing
Part Number Voltage Junction
Temperature Range Package
MIC2800-1.8/1.2/2.5YML MIC2800-G4JYML 1.8V/1.2V/2.5V –40°C to +125°C 16-Pin 3x3 MLF
®
MIC2800-1.8/1.2/2.6YML MIC2800-G4KYML 1.8V/1.2V/2.6V –40°C to +125°C 16-Pin 3x3 MLF
®
MIC2800-1.8/1.2/2.8YML MIC2800-G4MYML 1.8V/1.2V/2.8V –40°C to +125°C 16-Pin 3x3 MLF
®
MIC2800-1.8/1.2/3.3YML MIC2800-G4SYML 1.8V/1.2V/3.3V –40°C to +125°C 16-Pin 3x3 MLF
®
MIC2800-1.8/1.58/3.3YML MIC2800-G7SYML 1.8V/1.58V/3.3V –40°C to +125°C 16-Pin 3x3 MLF
®
MIC2800-1.87/1.2/2.8YML MIC2800-D24MYML 1.87V/1.2V/2.8V –40°C to +125°C 16-Pin 3x3 MLF
®
MIC2800-1.8/1.5/2.8YML MIC2800-GFMYML 1.8V/1.5V/2.8V –40°C to +125°C 16-Pin 3x3 MLF
®
MIC2800-Adj/1.2/3.3YML MIC2800-A4SYML Adj/1.2V/3.3V –40°C to +125°C 16-Pin 3x3 MLF
®
Notes:
Other voltage options available. Please contact Micrel for details. MLF
®
is a GREEN RoHS compliant package. Lead finish is NiPdAu. Mold
compound is Halogen Free.
DC/DC – Fixed Output Voltages (Range of 1.0V to 2.0V). Adjustable output voltage is available upon request.
LDO1 – Output Voltage Range of 0.8V to V
DC/DC
- V
DO.
LDO2 – Output Voltage Range of 0.8V to 3.6V.
Micrel, Inc. MIC2800
September 2007
3 M9999-090507-C
Pin Configur ation
3mm x 3mm MLF
®
(ML)
Fixed DC/DC Converter Output Voltage
Pin Description
Pin Number Pin Name Pin Function
1 _____
LOWQ
LOWQ Mode. Active Low Input. Logic High = Full Power 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 (Output): Internal power MOSFET output switches.
6 V
IN
Supply Input – DC/DC. Must be tied to PIN7 externally.
7 V
IN
Supply Input – LDO2. Must be tied to PIN6 externally.
8 LDO2 Output of regulator 2
9 FB
Feedback. Input to the error amplifier for DC to DC converter. adjust version, co
For fixed output voltages connect to V
OUT
and an internal resistor network sets the
output voltage
10 LDO LDO Output: Connect to V
OUT
of the DC/DC for LOWQ mode operation.
11 LDO1 Output of regulator 1
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 C
SET
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 C
BYP
Reference Bypass: Connect external 0.1µF to GND to reduce output noise. May be
left open.
15 EN1
Enable Input (DC/DC and LDO1). 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. MIC2800
September 2007
4 M9999-090507-C
Absolute Maximum Ratings(1)
Supply Voltage (V
IN
)............................................. 0V to +6V
Enable Input Voltage (V
EN
)................................... 0V to +6V
LOWQ Mode (V
LOWQ
). .......................................... 0V to +6V
Power Dissipation, Internally Limited
(3)
Lead Temperature (soldering, 10 sec.)...................... 260°C
Storage Temperature (T
s
) .........................–65°C to +150°C
EDS Rating
(4)
.................................................................. 2kV
Operating Ratings(2)
Supply voltage (V
IN
) ..................................... +2.7V to +5.5V
Enable Input Voltage (V
EN
)..................................... 0V to V
IN
LOWQ Mode (V
LOWQ
). ............................................ 0V to V
IN
Junction Temperature (T
J
) ........................ –40°C to +125°C
Junction Thermal Resistance
MLF-16 (θ
JA
) ......................................................45°C/W
Electrical Characteristics(5)
V
IN
= EN1 = EN2 = LOWQ = V
OUT(6)
+ 1V; C
OUTDC/DC
= 2.2µF, C
OUT1
= C
OUT2
= 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);
LDO2 Only (EN1 = LOW)
800
55
1100
85
95
µA
µA
µA
Ground Pin Current in
Shutdown
All EN = 0V 0.2 5 µA
Ground Pin Current
(LOWQ mode)
I
DC/DC
< I
LDO1
< I
LDO2
< 10mA
DC/DC and LDO1 OFF; I
LDO2
< 10mA
30
20
60
80
70
µA
µA
µA
Over-temperature Shutdown 160 °C
Over-temperature Shutdown
Hysteresis
23
°C
Enable Inputs (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 (See Timing Diagram)
Turn-on Time
(LDO1 and LDO2)
EN2=V
IN
EN1=V
IN
240
120
500
350 µs
µs
Turn-on Time (DC/DC) EN2=V
IN
; I
LOAD
= 300mA; C
BYP
= 0.1µF 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. MIC2800
September 2007
5 M9999-090507-C
Electrical Characteristics - DC/DC Converter
V
IN
= V
OUTDC/DC
+ 1; EN1 = V
IN
; EN2 = 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 %
%
Current Limit in PWM Mode V
FB
= 0.9*V
NOM
0.75 1 1.6 A
FB pin input current (ADJ only) 1 5 nA
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
%/V
Output Voltage Load Regulation 20mA < I
LOAD
< 300mA 0.2 1.5 %
Maximum Duty Cycle V
FB
≤ 0.4V 100 %
PWM Switch ON-Resistance
I
SW
= 150mA V
FB
= 0.7V
FB_NOM
I
SW
= -150mA V
FB
= 1.1V
FB_NOM
0.6
0.8
Oscillator Frequency 1.8 2 2.2 MHz
Output Voltage Noise C
OUT
= 2.2µF; C
BYP
= 0.1µF; 10Hz to 100KHz 60 µV
RMS
LOWQ = Low (Light Load Mode)
Variation from nominal V
OUT
-2.0 +2.0 % Output Voltage Accuracy
Variation from nominal V
OUT
; -40°C to +125°C -3.0 +3.0 %
Output Voltage Temp.
Coefficient
40 ppm/C
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 0.2 1.5 %
Ripple Rejection f = up to 1kHz; C
OUT
= 2.2µF; C
BYP
= 0.1µF
f = 20kHz; C
OUT
= 2.2µF; C
BYP
= 0.1µF
55
45
dB
dB
Current Limit V
OUT
= 0V 80 120 190 mA
Micrel, Inc. MIC2800
September 2007
6 M9999-090507-C
Electrical Characteristics - LDO1
V
IN
= V
OUTDC/DC
; EN1 = V
IN
; EN2 = GND; C
OUT1
= 2.2µF, I
OUT1
= 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
-2.0 +2.0 % Output Voltage Accuracy
Variation from nominal V
OUT
; -40°C to +125°C -3.0 +3.0 %
Output Current Capability V
IN
> 1.8V
V
IN
> 1.5V
300
120
mA
mA
Load Regulation I
OUT
= 100µA to 150mA
I
OUT
= 100µA to 300mA
0.17
0.3
1.5 %
%
Current Limit V
OUT
= 0V 350 500 700 mA
Ripple Rejection f = up to 1kHz; C
OUT
= 2.2µF; C
BYP
= 0.1µF
f = 20kHz; C
OUT
= 2.2µF; C
BYP
= 0.1µF
70
44
dB
dB
Output Voltage Noise C
OUT
= 2.2µF; C
BYP
= 0.1µF; 10Hz to 100KHz 30 µV
RMS
LOWQ = Low (Light Load Mode)
Variation from nominal V
OUT
-3.0 +3.0 % Output Voltage Accuracy
Variation from nominal V
OUT
; -40°C to +125°C -4.0 +4.0 %
Load Regulation I
OUT
= 100µA to 10mA 0.2 0.5
1.0
%
%
Current Limit V
OUT
= 0V 50 85 125 mA
Ripple Rejection f = up to 1kHz; C
OUT
= 2.2µF; C
BYP
= 0.1µF
f = 20kHz; C
OUT
= 2.2µF; C
BYP
= 0.1µF
70
42
dB
dB
Micrel, Inc. MIC2800
September 2007
7 M9999-090507-C
Electrical Characteristics - LDO2
V
IN
= V
OUTLDO2
+ 1.0V; EN1 = GND; EN2 = V
IN
; C
OUT2
= 2.2µF; I
OUTLDO2
= 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
-2.0 +2.0 % Output Voltage Accuracy
Variation from nominal V
OUT
; -40°C to +125°C -3.0 +3.0 %
Line Regulation V
IN
= V
OUT
+1V to 5.5V; I
OUT
= 100µA
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; C
OUT
= 2.2µF; C
BYP
= 0.1µF
f = 20kHz; C
OUT
= 2.2µF; C
BYP
= 0.1µF
75
40
dB
dB
Current Limit V
OUT
= 0V 400 550 850 mA
Output Voltage Noise C
OUT
= 2.2µF, C
BYP
=0.1µF, 10Hz to 100kHz 25 µV
RMS
LOWQ = Low (Light Load Mode)
Variation from nominal V
OUT
-3.0 +3.0 % Output Voltage Accuracy
Variation from nominal V
OUT
; -40°C to +125°C -4.0 +4.0 %
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; C
OUT
= 2.2µF; C
BYP
= 0.1µF
f = 20kHz; C
OUT
= 2.2µF; C
BYP
= 0.1µF
75
55
dB
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.
6. V
OUT
denotes the highest of the three output voltage plus one volt.
Micrel, Inc. MIC2800
September 2007
8 M9999-090507-C
Typical Characteristics (DC/DC PWM Mode)
50
55
60
65
70
75
80
85
90
95
100
100 200 300 400 500 600
OUTPUT CURRENT (mA)
DC/DC 1.87VOUT Efficiency
0
3V 3.6V
4.2V
L = 2.2µH
C
OUT
= 2.2µF
/LowQ = V
IN
100 200 300 400 500 600
OUTPUT CURRENT (mA)
50
55
60
65
70
75
80
85
90
95
100
DC/DC 1.8VOUT Efficiency
0
3V 3.6V
4.2V
L = 2.2µH
C
OUT
= 2.2µF
/LowQ = V
IN
0
200
400
600
800
1000
1200
1400
20 40 60 80
TEMPERATURE (°C)
DC/DC Current Limit
C
BYP
= 0.1µF
C
OUT
= 2.2µF
/LowQ = V
IN
EN1 = EN2 = V
IN
vs. Temperature
500
550
600
650
700
750
800
850
900
950
1000
2.7
SUPPLY VOLTAGE (V)
DC/DC Enable Threshold
5.53.4 4.1 4.8
ON
OFF
C
OUT
= 2.2µF
/LowQ = V
IN
vs. Supply Voltage
50
55
60
65
70
75
80
85
90
95
100
2.7
SUPPLY VOLTAGE (V)
DC/DC Turn-On Delay
5.23.2 4.2 4.73.7
vs. Supply Voltage
C
OUT
= 2.2µF
/LowQ = V
IN
Micrel, Inc. MIC2800
September 2007
9 M9999-090507-C
Typical Characteristics (DC/DC LowQ Mode)
0
10
20
30
40
50
60
Power Supply Rejection Rati o
(Input Voltage)
1
FREQUENCY (kHz)
0.10.01 10 100 1,000
4.2V
3.6V
I
OUT
= 50mA
V
OUT
= 1.8V
C
OUT
= 2.2µF
/LowQ = GND
0
10
20
30
40
50
60
70
80
Power Supply Rejection Rati o
(Output Current)
1
FREQUENCY (kHz)
0.10.01 10 100 1,000
100µA
0µA
50mA
V
IN
= 3.6V
V
OUT
= 1.8V
C
OUT
= 2.2µF
/LowQ = GND
0
20
60
80
100
2.7
SUPPLY VOLTAGE (V)
2.7
LDO Current Limit
3.4 4.8 5.54.1
vs. Supply Voltage
/LowQ = GND
C
OUT
= 2.2µF
40
1.84
1.85
1.86
1.87
1.88
1.89
1.90
10 20 30 40 50 60 70 80 90
OUTPUT CURRENT (mA)
LDO Output Voltage
V
IN
= 3.6V
V
OUT
= 1.87V
/LowQ = GND
C
OUT
= 2.2µF
vs. Output Current
0.001
0.01
0.1
1
10
DC/DC LowQ Mode
O u tput NoiseSpectral Density
1
FREQUENCY (kHz)
0.10.01 10 100 1,000 10,000
V
IN
= 4.2V
V
OUT
= 1.87V
C
OUT
= 2.2µF
/LowQ = GND
Micrel, Inc. MIC2800
September 2007
10 M9999-090507-C
Typical Characteristics (LDO1, LDO2)
0
10
20
30
40
50
60
70
80
90
100
Power Supply Rej ection Rati o
(LDO1 LowQ Mode)
1
FREQUENCY (kHz)
0.10.01 10 100 1,000
50mA
100µA
V
IN
= 4.2V
V
OUT
= 1.2V
/LowQ = GND
C
OUT
= 2.2µF
C
BYP
= 0.1µF
0
10
20
30
40
50
60
70
80
Power Supply Rejection Rati o
(LDO1 Normal Mo d e )
1
FREQUENCY (kHz)
0.10.01 10 100 1,000
50mA 100µA
V
IN
= 4.2V
V
OUT
= 1.2V
/LowQ = V
IN
C
OUT
= 2.2µF
C
BYP
= 0.1µF
150mA
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
1
FREQUENCY (kHz)
0.10.01 10 100 1,000
Power Supply Rejection Ratio
(LDO2 LowQ Mode)
50mA
100µA
V
IN
= 4.2V
V
OUT
= 2.8V
/LowQ = V
IN
C
OUT
= 2.2µF
C
BYP
= 0.01µF
10mA
0
10
20
30
40
50
60
70
80
90
100
Power Supply Rejecti on Ratio
(LDO2 Normal Mode)
1
FREQUENCY (kHz)
0.10.01 10 100 1,000
50mA
150mA
300mA
100µA
V
IN
= 4.2V
V
OUT
= 1.2V
/LowQ = V
IN
C
OUT
= 2.2µF
C
BYP
= 0.01µF
2.50
2.55
2.60
2.65
2.70
2.75
2.85
2.90
2.95
3.00
(LDO2) Output Voltage
20 40 60 80
TEMPERATURE (°C)
V
IN
= V
OUT
+ 1V
V
OUT
= 2.8V
C
BYP
= 0.1µF
C
OUT
= 2.2µF
EN1 = GND
EN2 = V
IN
2.80
vs. Temperature
30
35
40
50
55
60
65
70
Ground Curren t
20 40 60 80
TEMPERATURE (°C)
45
V
IN
= V
OUT
+ 1V
V
OUT
= 2.8V
C
BYP
= 0.1µF
C
OUT
= 2.2µF
/LowQ = V
IN
EN1 = GND
EN2 = V
IN
100mA
300mA
100µA
vs. Temperature
30
40
50
60
70
0 50 100 150 200 250 300
OUTPUT CURRENT (mA)
Ground Current
V
IN
= 2.8V
V
OUT
= 2.8V
C
BYP
= 0.1µF
C
OUT
= 2.2µF
vs. Output Current
0
20
40
60
80
100
120
140
0 50 100 150 200 250 300
OUTPUT CURRENT (mA)
(LDO2) Dropout Voltage
V
OUT
= 2.8V
C
BYP
= 0.1µF
C
OUT
= 2.2µF
/LowQ = V
IN
vs. Output Current
0.00
0.12
0.14
0.16
0.18
0.20
(LDO2) Dropo ut Voltage
20 40 60 80
TEMPERATURE (°C)
0.02
0.04
0.06
0.08
0.10 150mA
100mA
50mA
300mA
20mA
vs. Temperature
V
OUT
= 2.8V
C
OUT
= 2.2µF
C
BYP
= 0.1µF
/LowQ = V
IN
2.0
2.5
3.0
1.5 2.0 2.5 3.0 3.5
SUPPLY VOLTAGE (V)
Dropout Chararcteristics
150mA
300mA
100mA
C
OUT
= 2.2µF
C
BYP
= 0.1µF
/LowQ = V
IN
0.001
0.01
0.1
1
10
LDO1 Output Noise
Spectral Density
1
FREQUENCY (kHz)
0.10.01 10 100 1,000 10,000
V
IN
= 4.2V
V
OUT
= 1.2V
C
BYP
= 0.1µF
C
OUT
= 2.2µF
/LowQ = V
IN
0.001
0.01
0.1
1
10
LDO2 Output Noise
Spectral Density
1
FREQUENCY (kHz)
0.10.01 10 100 1,000 10,000
V
IN
= 4.2V
V
OUT
= 2.8V
C
BYP
= 0.1µF
C
OUT
= 2.2µF
/LowQ = V
IN
Micrel, Inc. MIC2800
September 2007
11 M9999-090507-C
Functional Characteristics
DC/DC Load Transient PWM Mode
Output Current
(100mA/div)
Time (20µs/div)
AC Coupled
(100mV/div)
Output Voltage
V
IN
= V
OUT
+ 1V
V
OUT
= 1.8V
C
OUT
= 2.2µF
C
BYP
= 0.01µF
/LowQ = V
IN
400mA
10mA
DC/DC Line Transient PWM Mode
Input Voltage
(1V/div)
Time (20µs/div)
AC Coupled
(100mV/div)
Output Volta
g
e
V
IN
= V
OUT
+ 1V
V
OUT
= 1.87V
C
OUT
= 2.2µF
C
BYP
= 0.01µF
/LowQ = V
IN
I
OUT
= 100mA
Enable Transient PWM Mode
Enable Volta
g
e
(500mV/div)
Time (40µs/div)
Output Volta
g
e
(500mV/div)
V
IN
= 3.6V
V
OUT
= 1.8V
C
OUT
= 2.2µF
C
BYP
= 0.01µF
/LowQ = V
IN
I
OUT
= 300mA
Micrel, Inc. MIC2800
September 2007
12 M9999-090507-C
Functional Characteristics
DC/DC Load Transient LowQ Mode
Output Current
(20mA/div)
Time (10µs/div)
AC Coupled
(20mV/div)
Output Volta
g
e
V
IN
= V
OUT
+ 1V
V
OUT
= 1.8V
C
OUT
= 2.2µF
C
BYP
= 0.01µF
/LowQ = GND
50mA
100µA
DC/DC Line Transient LowQ Mode
Input Voltage
(1V/div)
Time (20µs/div)
AC Coupled
(50mV/div)
Output Voltage
V
IN
= V
OUT
+ 1V
V
OUT
= 1.87V
C
OUT
= 2.2µF
C
BYP
= 0.01µF
/LowQ = GND
I
OUT
= 10mA
Enable Transient LowQ Mode
Time (20µs/div)
Output Voltage
(500mV/div)
V
IN
= EN1 = 3.8V
V
OUT
= 1.8V
C
OUT
= 2.2µF
C
BYP
= 0.01µF
/LowQ = GND
I
OUT
= 100µA
Enable Voltage
(2V/div)
Supply Voltage &
Micrel, Inc. MIC2800
September 2007
13 M9999-090507-C
Functional Characteristics
LDO2 Load Transient Normal Mode
Output Current
(100mA/div)
Time (4µs/div)
AC Coupled
(100mV/div)
Output Volta
g
e
V
IN
= 3.6V
V
OUT
= 2.8V
C
OUT
= 2.2µF
C
BYP
= 0.01µF
/LowQ = V
IN
300mA
100µA
LDO2 Load Transient LowQ Mode
Output Current
(25mA/div)
Time (200µs/div)
AC Coupled
(50mV/div)
Output Volta
g
e
V
IN
= V
OUT
+ 1V
V
OUT
= 2.8V
C
OUT
= 2.2µF
C
BYP
= 0.01µF
/LowQ = GND
50mA
100µA
LDO2 Line Transient Normal Mode
Input Voltage
(1V/div)
Time (20µs/div)
AC Coupled
(50mV/div)
Outpu
t
Volta
g
e
V
IN
= V
OUT
+ 1V
V
OUT
= 1.87V
C
OUT
= 2.2µF
C
BYP
= 0.01µF
/LowQ = V
IN
I
OUT
= 100mA
4V
5.5V
LDO2 Line Transient LowQ Mode
Input Voltage
(1V/div)
Time (40µs/div)
AC Coupled
(50mV/div)
Output Volta
g
e
VIN = VOUT + 1V
VOUT = 1.87V
COUT = 2.2µF
CBYP = 0.01µF
/LowQ = GND
IOUT = 10mA
4V
5.5V
Micrel, Inc. MIC2800
September 2007
14 M9999-090507-C
Functional Characteristics
DC/DC LowQ Mode to PWM Mode Transition
LowQ Voltage
(1V/div)
Time (100µs/div)
V
IN
= V
OUT
+ 1V
V
OUT
= 1.8V
C
OUT
= 2.2µF
C
BYP
= 0.01µF
I
OUT
= 100µA
AC Coupled
(50mV/div)
Outpu
t
Volta
g
e
DC/DC PWM Mode to LowQ Mode Transition
LowQ Voltage
(1V/div)
Time (100µs/div)
V
IN
= V
OUT
+ 1V
V
OUT
= 1.8V
C
OUT
= 2.2µF
C
BYP
= 0.01µF
I
OUT
= 50mA
AC Coupled
(50mV/div)
Output Volta
g
e
DC/DC PWM Wavefo
r
m
LowQ Voltage
(2V/div)
Time (400µs/div)
V
IN
= 4V
V
OUT
= 1.8V
C
OUT
= 2.2µF
AC Coupled
(10mV/div)
Output Volta
g
e
C
BYP
= 0.01µF
/LowQ = V
IN
L = 2.2µH
Micrel, Inc. MIC2800
September 2007
15 M9999-090507-C
Functional Characteristics
0.1
1
10
100
0 50 100 150
OUTPUT CURRENT (mA)
ESR vs. Load
LDO
STABLE AREA
0.1
1
10
100
0 50 100 150
OUTPUT CURRENT (mA)
ESR vs. Load
LDO1
STABLE AREA
0.1
1
10
100
0 50 100 150
OUTPUT CURRENT (mA)
ESR vs. Load
LDO2
STABLE AREA
Micrel, Inc. MIC2800
September 2007
16 M9999-090507-C
Functional Diagram
MIC2800 Fixed Block Diagram
LDO
SW
CSET
VIN
_
___
_
LOWQ
EN1
PGND
FB
SGND
EN2
DC to DC
LDO2
LDO1
POR
Reference and
Quick Start
CBYP
VOUT1
VOUT2
POR
VIN
CBIAS
Micrel, Inc. MIC2800
September 2007
17 M9999-090507-C
Application Notes
The MIC2800 is a digital power management IC with a
single integrated buck regulator and two independent
low dropout regulators. LDO1 is a 300mA low dropout
regulator that is using power supplied by the on board
buck regulator. LDO2 is a 300mA low dropout regulator
using the supply from the input pin. The buck regulator is
a 600mA PWM power supply that utilizes a /LOWQ light
load mode to maximize battery efficiency in 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, drawing only 20µA
of operating current. This allows the output to be
regulated through the LDO output, 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, 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 MIC2800 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.
VIN
Two input voltage pins provide power to the switch mode
regular and LDO2 separately. The LDO1 input voltage is
provided by the DC/DC LDO pin. VIN provides power to
the LDO section and the bias through an internal 6
resistor. Both VIN pins must be tied together.
For the switch mode regulator VIN provides power to the
MOSFET along with current limiting sensing. 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 layout
recommendations.
LDO
The LDO pin is the output of the linear regulator and
should be connected to the output. In /LOWQ mode
(/LOWQ <0.2V), the LDO provides the output voltage. In
PWM mode (/LOWQ >1V) the LDO pin provides power
to LDO1.
LDO1
Regulated output voltage of LDO1. Power is provided by
the DCDC switching regulator. Recommended output
capacitance is 2.2µF.
LDO2
Regulated output voltage of LDO2. Power is provided by
VIN. Recommended output capacitance is 2.2µF.
EN
Both enable inputs are active high, requiring 1.0V for
guaranteed operation. EN1 provides logic control of both
the DCDC regulator and LDO1. EN2 provides logic
control for LDO2 only. The enable inputs are CMOS
logic and cannot be left floating.
The enable pins provide logic level control of the
specified outputs. When both enable pins are in the off
state, supply current of the device is greatly reduced
(typically <1µA). When the DCDC 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 either 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 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 IQ of 20µA. 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 buck 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 10mA.
BIAS
The BIAS pin supplies the power to the internal control
and reference circuitry. The bias is powered from AVIN
through an internal 6 resistor. A small 0.1µF capacitor
is recommended for bypassing.
FB
Connect the feedback pin to VOUT.
Micrel, Inc. MIC2800
September 2007
18 M9999-090507-C
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. Refer to the
layout considerations for more details.
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. Refer to the
layout considerations for more details.
CSET
The SET 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 micro seconds is equal to the Cset in
picofarads.
POR Delay (µs) = CSET (pF)
CBYP
The internal reference voltage can be bypassed with a
capacitor to ground to reduce output noise and increase
power supply rejection (PSRR). A quick-start feature
allows for quick turn-on of the output voltage. The
recommended nominal bypass capacitor is 0.1µF, but it
can be increased, which will also result in an increase to
the start-up time.
Output Capacitor
LDO1 and LDO2 outputs require a 2.2µF ceramic output
capacitor for stability. The DC/DC switch mode regulator
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.
X7R/X5R dielectric-type ceramic capacitors are
recommended because of their temperature
performance. 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 is recommended on the VIN pin
for 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 layout
recommendations for proper layout of the input
capacitor.
Inductor Selection
The MIC2800 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
××
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛−
+=
Micrel, Inc. MIC2800
September 2007
19 M9999-090507-C
PCB Layout
Top Layer
Bottom Layer
Micrel, Inc. MIC2800
September 2007
20 M9999-090507-C
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.
