MIC2800
Digital Power Management IC
2MHz, 600mA DC/DC w/Dual
300mA/300mA Low V
IN
LDOs
LOWQ is a trademark of Micrel, Inc.
MLF and
Micro
LeadFrame 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
June 2006
M9999-061406
(408) 955-1690
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 LOWQTM mode, reducing the total
current draw while in this mode to less than 30A. In
LOWQTM mode, the output noise of the DC to DC
converter is 75V
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 Cap 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
LOWQTM mode
30A Total I
Q
when in LOWQTM mode
Tiny 16-pin 3mm x 3mm MLF
package
DC to DC Converter
Output current to 600mA in PWM mode
LOWQTM Mode: NO NOISE Light load mode
75V
RMS
output noise in LOWQTM 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
LDO
VIN
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
4.7F/
6.3V
C
BYP
0.01F
C
OUT2
2.2F
ceramic
C
OUT1
2.2F
ceramic
C
SET
0.01F
C
BIAS
0.1F
2.2F
ceramic
V
OUT
2.2H
GND
GND
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 = 2.2H
C
OUT
= 2.2F
/LowQ = V
IN
Micrel, Inc.
MIC2800
June 2006
2
M9999-061406
(408) 955-1690
Ordering Information
Part number
Manufacturing
Part Number
Voltage
Junction
Temperature Range
Package
MIC2800-1.8/1.2/2.8YML MIC2800-G4MYML
1.8V/1.2V/2.8V
40C to +125C
16-Pin 3x3 MLF
MIC2800-1.87/1.2/2.8YML MIC2800-D24MYML
1.87V/1.2V/2.8V
40C to +125C
16-Pin 3x3 MLF
MIC2800-1.8/1.5/2.8YML MIC2800-GFMYML
1.8V/1.5V/2.8V
40C to +125C
16-Pin 3x3 MLF
MIC2800-Adj/1.2/3.3YML MIC2800-A4SYML Adj/1.2V/3.3V
40C to +125C
16-Pin 3x3 MLF
Notes:
Other voltage options available. Please contact Micrel for details.
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
June 2006
3
M9999-061406
(408) 955-1690
Pin Configuration
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 0.1F
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 0.1F 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
June 2006
4
M9999-061406
(408) 955-1690
Absolute Maximum Ratings
(1)
Supply Voltage (V
IN
)............................................. 0V to +6V
Enable Input Voltage (V
EN
)................................... 0V to +6V
Power Dissipation, Internally Limited
(3)
Lead Temperature (soldering, 10 sec.)...................... 260C
Storage Temperature (T
s
) .........................65C to +150C
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
Junction Temperature (T
J
) ........................ 40C to +125C
Junction Thermal Resistance
MLF-16
(
JA
) ......................................................45C/W
Electrical Characteristics
(5)
V
IN
= EN1 = EN2 = LOWQ = V
OUT
(6)
+ 1V; C
OUTDC/DC
= 2.2F, C
OUT1
= C
OUT2
= 2.2F; I
OUTDC/DC
= 100mA;
I
OUTLDO1
= I
OUTLDO2
= 100A; T
J
= 25C,
bold
values indicate 40C < T
J
< +125C; 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
A
A
A
Ground Pin Current in
Shutdown
All EN = 0V
0.2
5
A
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
A
A
A
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
A
Enable Input Current
V
IH
> 1.0V
0.1
1
A
Turn-on Time (See Timing Diagram)
Turn-on Time
(LDO1 and LDO2)
EN2=V
IN
EN1=V
IN
240
120
500
350
s
s
Turn-on Time (DC/DC)
EN2=V
IN
; I
LOAD
= 300mA; C
BYP
= 0.1F
83
350
s
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 = 250A
10
100
mV
IPOR
Flag Leakage Current, Flag OFF
0.01
1
A
SET INPUT
SET Pin Current Source
VSET = 0V
0.75
1.25
1.75
A
SET Pin Threshold Voltage
POR = High
1.25
V
Micrel, Inc.
MIC2800
June 2006
5
M9999-061406
(408) 955-1690
Electrical Characteristics - DC/DC Converter
V
IN
= V
OUTDC/DC
+ 1; EN1 = V
IN
; EN2 = GND; I
OUTDC/DC
= 100mA ;L = 2.2H; C
OUTDC/DC
= 2.2F; T
J
= 25C,
bold
values
indicate 40C to + 125C; 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
= 2.2F; C
BYP
= 0.1F; 10Hz to 100KHz
60
V
RMS
LOWQ = Low (Light Load Mode)
Variation from nominal V
OUT
-2.0
+2.0
%
Output Voltage Accuracy
Variation from nominal V
OUT
; -40C to +125C
-3.0 +3.0
%
Output Voltage Temp.
Coefficient
40 ppm/C
Line Regulation
V
IN
= V
OUT
+ 1V to 5.5V; I
OUT
= 100A
0.02 0.3
0.6
%/V
%/V
Load Regulation
I
OUT
= 100A to 50mA
0.2
1.5
%
Ripple Rejection
f = up to 1kHz; C
OUT
= 2.2F; C
BYP
= 0.1F
f = 20kHz; C
OUT
= 2.2F; C
BYP
= 0.1F
55
45
dB
dB
Current Limit
V
OUT
= 0V
80
120
190
mA
Micrel, Inc.
MIC2800
June 2006
6
M9999-061406
(408) 955-1690
Electrical Characteristics - LDO1
V
IN
= V
OUTDC/DC
; EN1 = V
IN
; EN2 = GND; C
OUT1
= 2.2F, I
OUT1
= 100A; T
J
= 25C,
bold
values indicate
40C< T
J
< +125C; 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
; -40C to +125C
-3.0 +3.0
%
Output Current Capability
V
IN
> 1.8V
V
IN
> 1.5V
300
120
mA
mA
Load Regulation
I
OUT
= 100A to 150mA
I
OUT
= 100A 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
= 2.2F; C
BYP
= 0.1F
f = 20kHz; C
OUT
= 2.2F; C
BYP
= 0.1F
70
44
dB
dB
Output Voltage Noise
C
OUT
= 2.2F; C
BYP
= 0.1F; 10Hz to 100KHz
30
V
RMS
LOWQ = Low (Light Load Mode)
Variation from nominal V
OUT
-3.0
+3.0
%
Output Voltage Accuracy
Variation from nominal V
OUT
; -40C to +125C
-4.0 +4.0
%
Load Regulation
I
OUT
= 100A 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
= 2.2F; C
BYP
= 0.1F
f = 20kHz; C
OUT
= 2.2F; C
BYP
= 0.1F
70
42
dB
dB
Micrel, Inc.
MIC2800
June 2006
7
M9999-061406
(408) 955-1690
Electrical Characteristics - LDO2
V
IN
= V
OUTLDO2
+ 1.0V; EN1 = GND; EN2 = V
IN
; C
OUT2
= 2.2F; I
OUTLDO2
= 100A; T
J
= 25C,
bold
values indicate
40C< T
J
< +125C; 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
; -40C to +125C
-3.0 +3.0
%
Line Regulation
V
IN
= V
OUT
+1V to 5.5V; I
OUT
= 100A
0.02 0.3
0.6
%/V
Load Regulation
I
OUT
= 100A to 150mA
I
OUT
= 100A to 200mA
I
OUT
= 100A 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
= 2.2F; C
BYP
= 0.1F
f = 20kHz; C
OUT
= 2.2F; C
BYP
= 0.1F
75
40
dB
dB
Current Limit
V
OUT
= 0V
400
550
850
mA
Output Voltage Noise
C
OUT
= 2.2F, C
BYP
=0.1F, 10Hz to 100kHz
25
V
RMS
LOWQ = Low (Light Load Mode)
Variation from nominal V
OUT
-3.0
+3.0
%
Output Voltage Accuracy
Variation from nominal V
OUT
; -40C to +125C
-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
= 100A to 10mA
0.2
1.0
%
Dropout Voltage
I
OUT
= 10mA
22
35
50
mV
mV
Ripple Rejection
f = up to 1kHz; C
OUT
= 2.2F; C
BYP
= 0.1F
f = 20kHz; C
OUT
= 2.2F; C
BYP
= 0.1F
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
) /
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
June 2006
8
M9999-061406
(408) 955-1690
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 1.87V
OUT
Efficiency
0
3V
3.6V
4.2V
L = 2.2H
C
OUT
= 2.2F
/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 1.8V
OUT
Efficiency
0
3V
3.6V
4.2V
L = 2.2H
C
OUT
= 2.2F
/LowQ = V
IN
0
200
400
600
800
1000
1200
1400
20 40 60 80
TEMPERATURE (C)
DC/DC Current Limit
C
BYP
= 0.1F
C
OUT
= 2.2F
/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
5.5
3.4
4.1
4.8
ON
OFF
C
OUT
= 2.2F
/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
5.2
3.2
4.2
4.7
3.7
vs. Supply Voltage
C
OUT
= 2.2F
/LowQ = V
IN
Micrel, Inc.
MIC2800
June 2006
9
M9999-061406
(408) 955-1690
Typical Characteristics (DC/DC LowQ Mode)
0
10
20
30
40
50
60
Power Supply Rejection Ratio
(Input Voltage)
1
FREQUENCY (kHz)
0.1
0.01
10
100 1,000
4.2V
3.6V
I
OUT
= 50mA
V
OUT
= 1.8V
C
OUT
= 2.2F
/LowQ = GND
0
10
20
30
40
50
60
70
80
Power Supply Rejection Ratio
(Output Current)
1
FREQUENCY (kHz)
0.1
0.01
10
100 1,000
100A
0A
50mA
V
IN
= 3.6V
V
OUT
= 1.8V
C
OUT
= 2.2F
/LowQ = GND
0
20
60
80
100
2.7
SUPPLY VOLTAGE (V)
2.7
LDO Current Limit
3.4
4.8
5.5
4.1
vs. Supply Voltage
/LowQ = GND
C
OUT
= 2.2F
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
= 2.2F
vs. Output Current
0.001
0.01
0.1
1
10
DC/DC LowQ Mode
Output Noise Spectral Density
1
FREQUENCY (kHz)
0.1
0.01
10 100 1,000 10,000
V
IN
= 4.2V
V
OUT
= 1.87V
C
OUT
= 2.2F
/LowQ = GND
Micrel, Inc.
MIC2800
June 2006
10
M9999-061406
(408) 955-1690
Typical Characteristics (LDO1, LDO2)
0
10
20
30
40
50
60
70
80
90
100
Power Supply Rejection Ratio
(LDO1 LowQ Mode)
1
FREQUENCY (kHz)
0.1
0.01
10
100 1,000
50mA
100A
V
IN
= 4.2V
V
OUT
= 1.2V
/LowQ = GND
C
OUT
= 2.2F
C
BYP
= 0.1F
0
10
20
30
40
50
60
70
80
Power Supply Rejection Ratio
(LDO1 Normal Mode)
1
FREQUENCY (kHz)
0.1
0.01
10
100 1,000
50mA
100A
V
IN
= 4.2V
V
OUT
= 1.2V
/LowQ = V
IN
C
OUT
= 2.2F
C
BYP
= 0.1F
150mA
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
1
FREQUENCY (kHz)
0.1
0.01
10
100 1,000
Power Supply Rejection Ratio
(LDO2 LowQ Mode)
50mA
100A
V
IN
= 4.2V
V
OUT
= 2.8V
/LowQ = V
IN
C
OUT
= 2.2F
C
BYP
= 0.01F
10mA
0
10
20
30
40
50
60
70
80
90
100
Power Supply Rejection Ratio
(LDO2 Normal Mode)
1
FREQUENCY (kHz)
0.1
0.01
10
100 1,000
50mA
150mA
300mA
100A
V
IN
= 4.2V
V
OUT
= 1.2V
/LowQ = V
IN
C
OUT
= 2.2F
C
BYP
= 0.01F
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
= 0.1F
C
OUT
= 2.2F
EN1 = GND
EN2 = V
IN
2.80
vs. Temperature
30
35
40
50
55
60
65
70
Ground Current
20 40 60 80
TEMPERATURE (C)
45
V
IN
= V
OUT
+ 1V
V
OUT
= 2.8V
C
BYP
= 0.1F
C
OUT
= 2.2F
/LowQ = V
IN
EN1 = GND
EN2 = V
IN
100mA
300mA
100A
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
= 0.1F
C
OUT
= 2.2F
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
= 0.1F
C
OUT
= 2.2F
/LowQ = V
IN
vs. Output Current
0.00
0.12
0.14
0.16
0.18
0.20
(LDO2) Dropout 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
= 2.2F
C
BYP
= 0.1F
/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
= 2.2F
C
BYP
= 0.1F
/LowQ = V
IN
0.001
0.01
0.1
1
10
LDO1 Output Noise
Spectral Density
1
FREQUENCY (kHz)
0.1
0.01
10 100 1,000 10,000
V
IN
= 4.2V
V
OUT
= 1.2V
C
BYP
= 0.1F
C
OUT
= 2.2F
/LowQ = V
IN
0.001
0.01
0.1
1
10
LDO2 Output Noise
Spectral Density
1
FREQUENCY (kHz)
0.1
0.01
10 100 1,000 10,000
V
IN
= 4.2V
V
OUT
= 2.8V
C
BYP
= 0.1F
C
OUT
= 2.2F
/LowQ = V
IN
Micrel, Inc.
MIC2800
June 2006
11
M9999-061406
(408) 955-1690
Functional Characteristics
DC/DC Load Transient PWM Mode
Ou
tp
ut
C
u
r
re
n
t
(1
00mA
/
d
i
v)
Time (20s/div)
AC
Co
up
led
(10
0
mV/d
i
v
)
Ou
t
p
ut
V
o
lta
g
e
V
IN
= V
OUT
+ 1V
V
OUT
= 1.8V
C
OUT
= 2.2F
C
BYP
= 0.01F
/LowQ = V
IN
400mA
10mA
DC/DC Line Transient PWM Mode
Inpu
t
V
olt
a
g
e
(1V
/
d
i
v)
Time (20s/div)
A
C
C
oup
l
e
d
(100mV/
div
)
Ou
t
p
ut
V
o
l
t
a
g
e
V
IN
= V
OUT
+ 1V
V
OUT
= 1.87V
C
OUT
= 2.2F
C
BYP
= 0.01F
/LowQ = V
IN
I
OUT
= 100mA
Enable Transient PWM Mode
En
able
V
o
l
ta
g
e
(50
0
m
V
/d
i
v
)
Time (40s/div)
Outp
ut
V
o
l
t
a
g
e
(
5
00mV/
di
v)
V
IN
= 3.6V
V
OUT
= 1.8V
C
OUT
= 2.2F
C
BYP
= 0.01F
/LowQ = V
IN
I
OUT
= 300mA
Micrel, Inc.
MIC2800
June 2006
12
M9999-061406
(408) 955-1690
Functional Characteristics
DC/DC Load Transient LowQ Mode
Ou
tp
ut
C
u
r
r
e
nt
(2
0mA/
div
)
Time (10s/div)
AC
Co
up
led
(2
0
m
V
/
d
i
v)
Ou
t
p
ut
V
o
lta
g
e
V
IN
= V
OUT
+ 1V
V
OUT
= 1.8V
C
OUT
= 2.2F
C
BYP
= 0.01F
/LowQ = GND
50mA
100A
DC/DC Line Transient LowQ Mode
In
pu
t
V
ol
ta
g
e
(1
V/d
i
v
)
Time (20s/div)
AC Co
upl
ed
(
50m
V/di
v
)
Ou
tp
ut
V
o
ltag
e
V
IN
= V
OUT
+ 1V
V
OUT
= 1.87V
C
OUT
= 2.2F
C
BYP
= 0.01F
/LowQ = GND
I
OUT
= 10mA
Enable Transient LowQ Mode
Time (20s/div)
O
u
t
p
ut
V
ol
t
ag
e
(
500mV/di
v
)
V
IN
= EN1 = 3.8V
V
OUT
= 1.8V
C
OUT
= 2.2F
C
BYP
= 0.01F
/LowQ = GND
I
OUT
= 100A
Enabl
e
V
ol
t
a
g
e
(2
V
/
di
v
)
Suppl
y
V
ol
tage
&
Micrel, Inc.
MIC2800
June 2006
13
M9999-061406
(408) 955-1690
Functional Characteristics
LDO2 Load Transient Normal Mode
Outp
ut C
u
r
r
e
n
t
(10
0
m
A
/d
i
v
)
Time (4s/div)
AC Coup
l
e
d
(10
0
m
V
/d
i
v
)
O
u
t
put
V
o
lta
g
e
V
IN
= 3.6V
V
OUT
= 2.8V
C
OUT
= 2.2F
C
BYP
= 0.01F
/LowQ = V
IN
300mA
100A
LDO2 Load Transient LowQ Mode
O
u
t
p
u
t
C
u
rren
t
(2
5mA
/
di
v
)
Time (200s/div)
AC
C
o
up
le
d
(5
0mV
/
di
v
)
Out
p
ut
V
o
l
t
a
g
e
V
IN
= V
OUT
+ 1V
V
OUT
= 2.8V
C
OUT
= 2.2F
C
BYP
= 0.01F
/LowQ = GND
50mA
100A
LDO2 Line Transient Normal Mode
Input
V
ol
t
ag
e
(1
V
/
d
i
v)
Time (20s/div)
A
C
C
oupl
ed
(50
m
V/di
v
)
Ou
t
p
u
t
Vo
l
t
a
g
e
V
IN
= V
OUT
+ 1V
V
OUT
= 1.87V
C
OUT
= 2.2F
C
BYP
= 0.01F
/LowQ = V
IN
I
OUT
= 100mA
4V
5.5V
LDO2 Line Transient LowQ Mode
I
n
pu
t
V
ol
t
a
g
e
(1V
/
di
v)
Time (40s/div)
A
C
Coupl
e
d
(50mV
/
di
v)
O
u
tput
V
o
l
t
a
g
e
V
IN
= V
OUT
+ 1V
V
OUT
= 1.87V
C
OUT
= 2.2F
C
BYP
= 0.01F
/LowQ = GND
I
OUT
= 10mA
4V
5.5V
Micrel, Inc.
MIC2800
June 2006
14
M9999-061406
(408) 955-1690
Functional Characteristics
DC/DC LowQ Mode to PWM Mode Transition
LowQ
V
ol
tag
e
(1
V
/
d
i
v)
Time (100s/div)
V
IN
= V
OUT
+ 1V
V
OUT
= 1.8V
C
OUT
= 2.2F
C
BYP
= 0.01F
I
OUT
= 100A
A
C
C
oupl
ed
(5
0mV/di
v
)
Ou
t
p
u
t
Vo
l
t
a
g
e
DC/DC PWM Mode to LowQ Mode Transition
LowQ
V
ol
tag
e
(1
V
/
d
i
v)
Time (100s/div)
V
IN
= V
OUT
+ 1V
V
OUT
= 1.8V
C
OUT
= 2.2F
C
BYP
= 0.01F
I
OUT
= 50mA
A
C
Coupl
ed
(50mV/di
v
)
O
utput
V
ol
t
a
g
e
DC/DC PWM Waveform
Lo
wQ
V
o
lt
a
g
e
(2V/
div)
Time (400s/div)
V
IN
= 4V
V
OUT
= 1.8V
C
OUT
= 2.2F
AC Co
upl
ed
(
10m
V
/
di
v
)
Ou
tpu
t
V
o
l
t
a
g
e
C
BYP
= 0.01F
/LowQ = V
IN
L = 2.2H
Micrel, Inc.
MIC2800
June 2006
15
M9999-061406
(408) 955-1690
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
June 2006
16
M9999-061406
(408) 955-1690
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
June 2006
17
M9999-061406
(408) 955-1690
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 20A
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 4.7F 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 2.2F.
LDO2
Regulated output voltage of LDO2. Power is provided by
VIN. Recommended output capacitance is 2.2F.
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 <1A). 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 20A. 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 0.1F capacitor
is recommended for bypassing.
Micrel, Inc.
MIC2800
June 2006
18
M9999-061406
(408) 955-1690
FB
Connect the feedback pin to VOUT.
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 1.25A 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 (s) = 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 0.1F, 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 2.2F ceramic output
capacitor for stability. The DC/DC switch mode regulator
requires a 2.2F ceramic output capacitor to be stable.
All output capacitor values can be increased to improve
transient response, but performance has been optimized
for a 2.2F 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 1F 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 1F 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 2.2H 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 40C 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:
L
f
2
V
V
1
V
I
I
IN
OUT
OUT
OUT
PK
-
+
=
Micrel, Inc.
MIC2800
June 2006
19
M9999-061406
(408) 955-1690
PCB Layout
Top Layer
Micrel, Inc.
MIC2800
June 2006
20
M9999-061406
(408) 955-1690
Bottom Layer
Micrel, Inc.
MIC2800
June 2006
21
M9999-061406
(408) 955-1690
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.
PDF 
ZIP