MICREL MIC2800-1.8/1.2/3.3YML

MIC2800
Digital Power Management IC
2MHz, 600mA DC/DC w/Dual
300mA/300mA Low VIN LDOs
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 75µVRMS, 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 IQ 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
–
75µVRMS 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
DC/DC 1.8VOUT Efficiency
100
95
3.6V
3V
90
85
4.2V
80
75
70
65
60
L = 2.2µH
COUT = 2.2µF
55
/LowQ = VIN
50
0 100 200 300 400 500 600
OUTPUT CURRENT (mA)
MIC2800-xxxYML
VIN
2.7V to 5.5V
4.7µF/
6.3V
CBYP
0.01µF
VIN
VIN
EN1
LOWQ
EN2
CBYP
CBIAS
PGND
CBIAS
0.1µF
LDO
SW
FB
LDO1
LDO2
POR
CSET
SGND
CSET
0.01µF
VOUT
2.2µH
Memory/DSP
2.2µF
ceramic
Baseband
COUT2
2.2µF
ceramic
COUT1
2.2µF
ceramic
GND
GND
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
Micrel, Inc.
MIC2800
Ordering Information
Part number
Manufacturing
Part Number
Voltage
Junction
Temperature Range
Package
MIC2800-1.8/1.2/2.5YML
MIC2800-1.8/1.2/2.6YML
MIC2800-1.8/1.2/2.8YML
MIC2800-1.8/1.2/3.3YML
MIC2800-1.8/1.58/3.3YML
MIC2800-1.87/1.2/2.8YML
MIC2800-1.8/1.5/2.8YML
MIC2800-Adj/1.2/3.3YML
MIC2800-G4JYML
MIC2800-G4KYML
MIC2800-G4MYML
MIC2800-G4SYML
MIC2800-G7SYML
MIC2800-D24MYML
MIC2800-GFMYML
MIC2800-A4SYML
1.8V/1.2V/2.5V
1.8V/1.2V/2.6V
1.8V/1.2V/2.8V
1.8V/1.2V/3.3V
1.8V/1.58V/3.3V
1.87V/1.2V/2.8V
1.8V/1.5V/2.8V
Adj/1.2V/3.3V
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
16-Pin 3x3 MLF®
16-Pin 3x3 MLF®
16-Pin 3x3 MLF®
16-Pin 3x3 MLF®
16-Pin 3x3 MLF®
16-Pin 3x3 MLF®
16-Pin 3x3 MLF®
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 VDC/DC - VDO.
LDO2 – Output Voltage Range of 0.8V to 3.6V.
September 2007
2
M9999-090507-C
Micrel, Inc.
MIC2800
Pin Configuration
®
3mm x 3mm MLF (ML)
Fixed DC/DC Converter Output Voltage
Pin Description
Pin Number
1
Pin Name
_____
LOWQ
2
BIAS
3
4
5
6
7
8
SGND
PGND
SW
VIN
VIN
LDO2
9
FB
10
11
LDO
LDO1
12
POR
13
CSET
14
CBYP
15
EN1
16
EN2
September 2007
Pin Function
LOWQ Mode. Active Low Input. Logic High = Full Power Mode; Logic Low =
LOWQ Mode; Do not leave floating.
Internal circuit bias supply. It must be de-coupled to signal ground with a 0.1µF
capacitor and should not be loaded.
Signal ground.
Power ground.
Switch (Output): Internal power MOSFET output switches.
Supply Input – DC/DC. Must be tied to PIN7 externally.
Supply Input – LDO2. Must be tied to PIN6 externally.
Output of regulator 2
Feedback. Input to the error amplifier for DC to DC converter. adjust version, co
For fixed output voltages connect to VOUT and an internal resistor network sets the
output voltage
LDO Output: Connect to VOUT of the DC/DC for LOWQ mode operation.
Output of regulator 1
Power-On Reset Output: Open-drain output. Active low indicates an output
undervoltage condition on either one of the three regulated outputs.
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.
Reference Bypass: Connect external 0.1µF to GND to reduce output noise. May be
left open.
Enable Input (DC/DC and LDO1). Active High Input. Logic High = On; Logic Low =
Off; Do not leave floating.
Enable Input (LDO 2). Active High Input. Logic High = On; Logic Low = Off; Do not
leave floating
3
M9999-090507-C
Micrel, Inc.
MIC2800
Absolute Maximum Ratings(1)
Operating Ratings(2)
Supply Voltage (VIN) ............................................. 0V to +6V
Enable Input Voltage (VEN)................................... 0V to +6V
LOWQ Mode (VLOWQ). .......................................... 0V to +6V
Power Dissipation, Internally Limited(3)
Lead Temperature (soldering, 10 sec.)...................... 260°C
Storage Temperature (Ts) .........................–65°C to +150°C
EDS Rating(4) .................................................................. 2kV
Supply voltage (VIN) ..................................... +2.7V to +5.5V
Enable Input Voltage (VEN)..................................... 0V to VIN
LOWQ Mode (VLOWQ). ............................................ 0V to VIN
Junction Temperature (TJ) ........................ –40°C to +125°C
Junction Thermal Resistance
MLF-16 (θJA) ......................................................45°C/W
Electrical Characteristics(5)
VIN = EN1 = EN2 = LOWQ = VOUT(6) + 1V; COUTDC/DC = 2.2µF, COUT1 = COUT2 = 2.2µF; IOUTDC/DC = 100mA;
IOUTLDO1 = IOUTLDO2 = 100µA; TJ = 25°C, bold values indicate –40°C < TJ < +125°C; unless noted.
Parameter
UVLO Threshold
UVLO Hysteresis
Ground Pin Current
Ground Pin Current in
Shutdown
Ground Pin Current
(LOWQ mode)
Conditions
Rising input voltage during turn-on
VFB = GND (not switching);
Typ
2.55
100
800
LDO2 Only (EN1 = LOW)
55
All EN = 0V
0.2
IDC/DC < ILDO1 < ILDO2 < 10mA
30
DC/DC and LDO1 OFF; ILDO2 < 10mA
Over-temperature Shutdown
Over-temperature Shutdown
Hysteresis
Enable Inputs (EN1; EN2; /LOWQ )
Enable Input Voltage
Logic Low
Logic High
Enable Input Current
VIL < 0.2V
VIH > 1.0V
Turn-on Time (See Timing Diagram)
Turn-on Time
EN2=VIN
(LDO1 and LDO2)
EN1=VIN
Turn-on Time (DC/DC)
EN2=VIN; ILOAD = 300mA; CBYP = 0.1µF
POR Output
VTH
Low Threshold, % of nominal (VDC/DC or VLDO1 or VLDO2)
(Flag ON)
High Threshold, % of nominal (VDC/DC AND VLDO1 AND
VLDO2) (Flag OFF)
VOL
POR Output Logic Low Voltage; IL = 250µA
IPOR
Flag Leakage Current, Flag OFF
SET INPUT
SET Pin Current Source
VSET = 0V
SET Pin Threshold Voltage
POR = High
September 2007
Min
2.45
4
20
160
23
Max
2.65
1100
Units
V
mV
µA
85
95
5
µA
µA
µA
60
80
70
µA
µA
µA
°C
°C
0.2
0.1
0.1
1
1
V
V
µA
µA
240
120
83
500
350
350
µs
µs
µs
1.0
90
0.75
91
%
96
99
%
10
0.01
100
1
mV
µA
1.25
1.25
1.75
µA
V
M9999-090507-C
Micrel, Inc.
MIC2800
Electrical Characteristics - DC/DC Converter
VIN = VOUTDC/DC + 1; EN1 = VIN; EN2 = GND; IOUTDC/DC = 100mA ;L = 2.2µH; COUTDC/DC = 2.2µF; TJ = 25°C, bold values
indicate –40°C to + 125°C; unless noted.
Parameter
Conditions
Min
Nominal VOUT tolerance
-2
-3
0.75
Typ
Max
Units
+2
+3
1.6
5
%
%
A
nA
%/V
%/V
%
%
Ω
Ω
MHz
LOWQ = High (Full Power Mode)
Fixed Output Voltages
Current Limit in PWM Mode
FB pin input current (ADJ only)
Output Voltage Line Regulation
Output Voltage Load Regulation
Maximum Duty Cycle
PWM Switch ON-Resistance
VFB = 0.9*VNOM
VOUT > 2.4V; VIN = VOUT + 300mV to 5.5V, ILOAD= 100mA
VOUT < 2.4V; VIN = 2.7V to 5.5V, ILOAD= 100mA
20mA < ILOAD < 300mA
VFB ≤ 0.4V
ISW = 150mA VFB = 0.7VFB_NOM
ISW = -150mA VFB = 1.1VFB_NOM
Oscillator Frequency
Output Voltage Noise
Load Regulation
Ripple Rejection
COUT = 2.2µF; CBYP = 0.1µF; 10Hz to 100KHz
Current Limit
September 2007
IOUT = 100µA to 50mA
f = up to 1kHz; COUT = 2.2µF; CBYP = 0.1µF
f = 20kHz; COUT = 2.2µF; CBYP = 0.1µF
VOUT = 0V
5
0.2
1.5
0.6
0.8
2
2.2
100
1.8
LOWQ = Low (Light Load Mode)
Output Voltage Accuracy
Variation from nominal VOUT
Variation from nominal VOUT; -40°C to +125°C
Output Voltage Temp.
Coefficient
Line Regulation
VIN = VOUT + 1V to 5.5V; IOUT = 100µA
1
1
0.2
60
-2.0
-3.0
µVRMS
+2.0
+3.0
%
%
ppm/C
0.3
0.6
1.5
%/V
%/V
%
dB
dB
mA
40
0.02
80
0.2
55
45
120
190
M9999-090507-C
Micrel, Inc.
MIC2800
Electrical Characteristics - LDO1
VIN = VOUTDC/DC; EN1 = VIN; EN2 = GND; COUT1 = 2.2µF, IOUT1 = 100µA; TJ = 25°C, bold values indicate
–40°C< TJ < +125°C; unless noted.
Parameter
Conditions
Min
LOWQ = High (Full Power Mode)
Output Voltage Accuracy
Variation from nominal VOUT
Variation from nominal VOUT; -40°C to +125°C
Output Current Capability
VIN > 1.8V
VIN > 1.5V
Load Regulation
IOUT = 100µA to 150mA
IOUT = 100µA to 300mA
Current Limit
VOUT = 0V
Ripple Rejection
f = up to 1kHz; COUT = 2.2µF; CBYP = 0.1µF
f = 20kHz; COUT = 2.2µF; CBYP = 0.1µF
Output Voltage Noise
COUT = 2.2µF; CBYP = 0.1µF; 10Hz to 100KHz
LOWQ = Low (Light Load Mode)
Output Voltage Accuracy
Variation from nominal VOUT
Variation from nominal VOUT; -40°C to +125°C
Load Regulation
IOUT = 100µA to 10mA
Current Limit
Ripple Rejection
September 2007
VOUT = 0V
f = up to 1kHz; COUT = 2.2µF; CBYP = 0.1µF
f = 20kHz; COUT = 2.2µF; CBYP = 0.1µF
6
Typ
-2.0
-3.0
300
120
350
0.17
0.3
500
70
44
30
-3.0
-4.0
0.2
50
85
70
42
Max
Units
+2.0
+3.0
%
%
mA
mA
%
%
mA
dB
dB
µVRMS
1.5
700
+3.0
+4.0
0.5
1.0
125
%
%
%
%
mA
dB
dB
M9999-090507-C
Micrel, Inc.
MIC2800
Electrical Characteristics - LDO2
VIN = VOUTLDO2 + 1.0V; EN1 = GND; EN2 = VIN; COUT2 = 2.2µF; IOUTLDO2 = 100µA; TJ = 25°C, bold values indicate
–40°C< TJ < +125°C; unless noted.
Parameter
Conditions
Min
LOWQ = High (Full Power Mode)
Output Voltage Accuracy
Variation from nominal VOUT
Variation from nominal VOUT; -40°C to +125°C
Line Regulation
VIN = VOUT +1V to 5.5V; IOUT = 100µA
-2.0
-3.0
Load Regulation
Dropout Voltage
Ripple Rejection
Current Limit
Output Voltage Noise
IOUT = 100µA to 150mA
IOUT = 100µA to 200mA
IOUT = 100µA to 300mA
IOUT = 150mA
IOUT = 200mA
IOUT = 300mA
f = up to 1kHz; COUT = 2.2µF; CBYP = 0.1µF
f = 20kHz; COUT = 2.2µF; CBYP = 0.1µF
VOUT = 0V
COUT = 2.2µF, CBYP =0.1µF, 10Hz to 100kHz
LOWQ = Low (Light Load Mode)
Output Voltage Accuracy
Variation from nominal VOUT
Variation from nominal VOUT; -40°C to +125°C
Line Regulation
VIN = VOUT +1V to 5.5V
Typ
0.02
400
0.20
0.25
0.40
70
94
142
75
40
550
25
-3.0
-4.0
0.02
Load Regulation
Dropout Voltage
IOUT = 100µA to 10mA
IOUT = 10mA
0.2
22
Ripple Rejection
f = up to 1kHz; COUT = 2.2µF; CBYP = 0.1µF
f = 20kHz; COUT = 2.2µF; CBYP = 0.1µF
VIN = 2.7V; VOUT = 0V
75
55
85
Current Limit
50
Max
Units
+2.0
+3.0
0.3
0.6
%
%
%/V
1.5
300
850
+3.0
+4.0
0.3
0.6
1.0
35
50
125
%
%
%
mV
mV
mV
dB
dB
mA
µVRMS
%
%
%/V
%
mV
mV
dB
dB
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 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, 1.5k in series with 100pF.
5. Specification for packaged product only.
6. VOUT denotes the highest of the three output voltage plus one volt.
September 2007
7
M9999-090507-C
Micrel, Inc.
MIC2800
Typical Characteristics (DC/DC PWM Mode)
DC/DC 1.8VOUT Efficiency
DC/DC 1.87VOUT Efficiency
100
95
100
95
90
85
3V
3.6V
90
85
4.2V
80
75
80
3.6V
1200
1000
4.2V
800
75
70
70
600
65
65
60
L = 2.2µH
COUT = 2.2µF
/LowQ = VIN
55
50
0
1000
1400
3V
100 200 300 400 500 600
OUTPUT CURRENT (mA)
DC/DC Enable Threshold
vs. Supply Voltage
950
ON
800
750
700
OFF
650
600
500
2.7
100
L = 2.2µH
COUT = 2.2µF
/LowQ = VIN
100 200 300 400 500 600
OUTPUT CURRENT (mA)
200
0
COUT = 2.2µF
CBYP = 0.1µF
/LowQ = VIN
EN1 = EN2 = VIN
20 40 60 80
TEMPERATURE (°C)
DC/DC Turn-On Delay
vs. Supply Voltage
95
900
850
550
400
60
55
50
0
DC/DC Current Limit
vs. Temperature
90
85
80
75
70
65
60
COUT = 2.2µF
/LowQ = VIN
3.4
4.1
4.8
5.5
SUPPLY VOLTAGE (V)
September 2007
COUT = 2.2µF
/LowQ = VIN
55
50
2.7
3.2 3.7 4.2 4.7 5.2
SUPPLY VOLTAGE (V)
8
M9999-090507-C
Micrel, Inc.
MIC2800
Typical Characteristics (DC/DC LowQ Mode)
Power Supply Rejection Ratio
(Input Voltage)
60
4.2V
80
0µA
70
50
40
Power Supply Rejection Ratio
(Output Current)
3.6V
80
60
100µA
50
30
40
40
IOUT = 50mA
10 VOUT = 1.8V
COUT = 2.2µF
/LowQ = GND
0
0.01 0.1
1
10
100 1,000
FREQUENCY (kHz)
20 VIN = 3.6V
VOUT = 1.8V
10 COUT = 2.2µF
/LowQ = GND
0
0.01 0.1
1
10
100 1,000
FREQUENCY (kHz)
LDO Output Voltage
vs. Output Current
DC/DC LowQ Mode
Output Noise Spectral Density
1.90
60
50mA
30
20
100
LDO Current Limit
vs. Supply Voltage
20
0
2.7
COUT = 2.2µF
/LowQ = GND
3.4
4.1
4.8
5.5
SUPPLY VOLTAGE (V)
10
1.89
1
1.88
1.87
0.1
1.86
1.85
1.84
VIN = 3.6V
VOUT = 1.87V
COUT = 2.2µF
/LowQ = GND
10 20 30 40 50 60 70 80 90
OUTPUT CURRENT (mA)
September 2007
0.01 VIN = 4.2V
VOUT = 1.87V
COUT = 2.2µF
/LowQ = GND
0.001
0.01 0.1
1
10 100 1,000 10,000
FREQUENCY (kHz)
9
M9999-090507-C
Micrel, Inc.
MIC2800
Typical Characteristics (LDO1, LDO2)
Power Supply Rejection Ratio
(LDO1 LowQ Mode)
Power Supply Rejection Ratio
(LDO1 Normal Mode)
Power Supply Rejection Ratio
(LDO2 LowQ Mode)
100
80
-90
90
70
-80
60
-70
80
70
50mA
100µA
60
50
50mA
100µA
150mA
30 VIN = 4.2V
VOUT = 1.2V
20 COUT = 2.2µF
10 /LowQ = GND
CBYP = 0.1µF
0
0.01 0.1
1
10
100 1,000
FREQUENCY (kHz)
Power Supply Rejection Ratio
(LDO2 Normal Mode)
100
100µA
90
300mA
VIN = 4.2V
20 VOUT = 1.2V
COUT = 2.2µF
10 /LowQ = VIN
CBYP = 0.1µF
0
0.01 0.1
1
10
100 1,000
FREQUENCY (kHz)
(LDO2) Output Voltage
vs. Temperature
2.95
80
70
150mA
50
50mA
40
30 VIN = 4.2V
VOUT = 1.2V
20 COUT = 2.2µF
10 /LowQ = VIN
CBYP = 0.01µF
0
0.01 0.1
1
10
100 1,000
FREQUENCY (kHz)
Ground Current
vs. Output Current
70
2.65
2.60
2.55
2.50
140
50
VIN = VOUT + 1V
VOUT = 2.8V
COUT = 2.2µF
CBYP = 0.1µF
EN1 = GND
EN2 = VIN
20 40 60 80
TEMPERATURE (°C)
(LDO2) Dropout Voltage
vs. Output Current
100
80
50
60
40
VIN = 2.8V
VOUT = 2.8V
COUT = 2.2µF
CBYP = 0.1µF
40
30
0
20
50 100 150 200 250 300
OUTPUT CURRENT (mA)
0
0
Dropout Chararcteristics
3.0
10
COUT = 2.2µF
CBYP = 0.1µF
/LowQ = VIN
100µA
55
120
60
70
Ground Current
vs. Temperature
60
2.80
2.75
2.70
-30 VIN = 4.2V
V
= 2.8V
-20 COUT = 2.2µF
OUT
-10 /LowQ = VIN
CBYP = 0.01µF
0
0.01 0.1
1
10
100 1,000
FREQUENCY (kHz)
65
2.90
2.85
60
100µA
-40
30
3.00
10mA
-50
40
50
40
-60
50mA
VOUT = 2.8V
COUT = 2.2µF
CBYP = 0.1µF
/LowQ = VIN
50 100 150 200 250 300
OUTPUT CURRENT (mA)
LDO1 Output Noise
Spectral Density
45
40
35
30
300mA
VIN = VOUT + 1V
100mA VOUT = 2.8V
COUT = 2.2µF
CBYP = 0.1µF
/LowQ = VIN
EN1 = GND
EN2 = VIN
20 40 60 80
TEMPERATURE (°C)
(LDO2) Dropout Voltage
vs. Temperature
0.20
VOUT = 2.8V
0.18 COUT = 2.2µF
C
0.16 BYP = 0.1µF
/LowQ = VIN
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0.00
10
1
1
0.1
0.1
300mA
150mA
100mA
50mA
20mA
20 40 60 80
TEMPERATURE (°C)
LDO2 Output Noise
Spectral Density
100mA
150mA
2.5
300mA
2.0
1.5
2.0
2.5
3.0
SUPPLY VOLTAGE (V)
September 2007
3.5
VIN = 4.2V
0.01 VOUT = 1.2V
COUT = 2.2µF
CBYP = 0.1µF
/LowQ = VIN
0.001
0.01 0.1 1
10 100 1,000 10,000
FREQUENCY (kHz)
10
VIN = 4.2V
0.01 VOUT = 2.8V
COUT = 2.2µF
CBYP = 0.1µF
/LowQ = VIN
0.001
0.01 0.1 1
10 100 1,000 10,000
FREQUENCY (kHz)
M9999-090507-C
Micrel, Inc.
MIC2800
Functional Characteristics
DC/DC Load Transient PWM Mode
DC/DC Line Transient PWM Mode
VIN = VOUT + 1V
Input Voltage
(1V/div)
VOUT = 1.8V
CBYP = 0.01µF
/LowQ = VIN
VIN = VOUT + 1V
VOUT = 1.87V
COUT = 2.2µF
CBYP = 0.01µF
Output Voltage
AC Coupled
(100mV/div)
Output Current
(100mA/div)
Output Voltage
AC Coupled
(100mV/div)
COUT = 2.2µF
400mA
10mA
/LowQ = VIN
IOUT = 100mA
Time (20µs/div)
Time (20µs/div)
Output Voltage
(500mV/div)
Enable Voltage
(500mV/div)
Enable Transient PWM Mode
VIN = 3.6V
VOUT = 1.8V
COUT = 2.2µF
CBYP = 0.01µF
/LowQ = VIN
IOUT = 300mA
Time (40µs/div)
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Micrel, Inc.
MIC2800
Functional Characteristics
DC/DC Load Transient LowQ Mode
DC/DC Line Transient LowQ Mode
VIN = VOUT + 1V
Input Voltage
(1V/div)
Output Current
(20mA/div)
50mA
VOUT = 1.8V
COUT = 2.2µF
CBYP = 0.01µF
/LowQ = GND
VIN = VOUT + 1V
VOUT = 1.87V
COUT = 2.2µF
100µA
CBYP = 0.01µF
Output Voltage
AC Coupled
(20mV/div)
Output Voltage
AC Coupled
(50mV/div)
/LowQ = GND
IOUT = 10mA
Time (20µs/div)
Time (10µs/div)
Output Voltage
(500mV/div)
Supply Voltage &
Enable Voltage
(2V/div)
Enable Transient LowQ Mode
VIN = EN1 = 3.8V
VOUT = 1.8V
COUT = 2.2µF
CBYP = 0.01µF
/LowQ = GND
IOUT = 100µA
Time (20µs/div)
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Micrel, Inc.
MIC2800
Functional Characteristics
LDO2 Load Transient LowQ Mode
Output Voltage
AC Coupled
(50mV/div)
Output Voltage
AC Coupled
(100mV/div)
LDO2 Load Transient Normal Mode
VIN = 3.6V
VOUT = 2.8V
Output Current
(100mA/div)
300mA
VIN = VOUT + 1V
VOUT = 2.8V
COUT = 2.2µF
COUT = 2.2µF
CBYP = 0.01µF
50mA /LowQ = GND
CBYP = 0.01µF
Output Current
(25mA/div)
/LowQ = VIN
100µA
100µA
Time (200µs/div)
Time (4µs/div)
Input Voltage
(1V/div)
LDO2 Line Transient LowQ Mode
5.5V
VIN = VOUT + 1V
4V
VOUT = 1.87V
4V
VIN = VOUT + 1V
VOUT = 1.87V
COUT = 2.2µF
CBYP = 0.01µF
CBYP = 0.01µF
/LowQ = VIN
/LowQ = GND
IOUT = 100mA
IOUT = 10mA
Time (40µs/div)
Time (20µs/div)
September 2007
5.5V
COUT = 2.2µF
Output Voltage
AC Coupled
(50mV/div)
Output Voltage
AC Coupled
(50mV/div)
Input Voltage
(1V/div)
LDO2 Line Transient Normal Mode
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M9999-090507-C
Micrel, Inc.
MIC2800
Functional Characteristics
DC/DC LowQ Mode to PWM Mode Transition
LowQ Voltage
(1V/div)
LowQ Voltage
(1V/div)
DC/DC PWM Mode to LowQ Mode Transition
VIN = VOUT + 1V
VOUT = 1.8V
VOUT = 1.8V
COUT = 2.2µF
COUT = 2.2µF
CBYP = 0.01µF
Output Voltage
AC Coupled
(50mV/div)
Output Voltage
AC Coupled
(50mV/div)
VIN = VOUT + 1V
CBYP = 0.01µF
IOUT = 100µA
IOUT = 50mA
Time (100µs/div)
Time (100µs/div)
VIN = 4V
VOUT = 1.8V
COUT = 2.2µF
CBYP = 0.01µF
/LowQ = VIN
L = 2.2µH
Output Voltage
AC Coupled
(10mV/div)
LowQ Voltage
(2V/div)
DC/DC PWM Waveform
Time (400µs/div)
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Micrel, Inc.
MIC2800
Functional Characteristics
100
ESR vs. Load
LDO
100
10
10
STABLE AREA
STABLE AREA
1
1
0.1
0
100
ESR vs. Load
LDO1
0.1
0
50
100
150
OUTPUT CURRENT (mA)
50
100
150
OUTPUT CURRENT (mA)
ESR vs. Load
LDO2
10
STABLE AREA
1
0.1
0
September 2007
50
100
150
OUTPUT CURRENT (mA)
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M9999-090507-C
Micrel, Inc.
MIC2800
Functional Diagram
VIN
VIN
CBIAS
LDO
DC to DC
SW
EN1
_____
LOWQ
FB
EN2
CBYP
LDO1
VOUT1
LDO2
VOUT2
Reference and
Quick Start
PGND
POR
SGND
POR
CSET
MIC2800 Fixed Block Diagram
September 2007
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M9999-090507-C
Micrel, Inc.
MIC2800
LDO2
Regulated output voltage of LDO2. Power is provided by
VIN. Recommended output capacitance is 2.2µF.
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.
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.
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 6Ω
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.
BIAS
The BIAS pin supplies the power to the internal control
and reference circuitry. The bias is powered from AVIN
through an internal 6Ω resistor. A small 0.1µF capacitor
is recommended for bypassing.
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.
FB
Connect the feedback pin to VOUT.
LDO1
Regulated output voltage of LDO1. Power is provided by
the DCDC switching regulator. Recommended output
capacitance is 2.2µF.
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M9999-090507-C
Micrel, Inc.
MIC2800
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.
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.
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.
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.
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:
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.
IPK = IOUT
⎛
V
VOUT ⎜⎜1 − OUT
VIN
⎝
+
2× f ×L
⎞
⎟⎟
⎠
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
September 2007
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Micrel, Inc.
MIC2800
PCB Layout
Top Layer
Bottom Layer
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Micrel, Inc.
MIC2800
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.
September 2007
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