MIC2800 [MICREL]
Digital Power Management IC 2MHz, 600mA DC/DC w/Dual 300mA/300mA Low VIN LDOs; 数字电源管理IC为2MHz ， 600毫安DC / DC W /双路，300mA / 300mA低压LDO的VIN
| 型号： | MIC2800 |
| 厂家： | 
MICREL SEMICONDUCTOR |
| 描述： | Digital Power Management IC 2MHz, 600mA DC/DC w/Dual 300mA/300mA Low VIN LDOs |
| 文件： | 总21页 (文件大小：633K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MIC2800
Digital Power Management IC
2MHz, 600mA DC/DC w/Dual
300mA/300mA Low VIN LDOs
• Integrated power-on reset (OR function for all outputs)
General Description
–
Adjustable delay time
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.
• 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
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.
–
–
–
Ideal for 1.8V to 1.5V conversion
300mA output current from 1.8V input
Output voltage down to 0.8V
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.
• LDO2 – 300mA output current capable
• Thermal Shutdown Protection
• Current Limit Protection
Applications
• Mobile phones
• PDAs
Data sheets and support documentation can be found on
Micrel’s web site at www.micrel.com.
• GPS receivers
• Digital still cameras
• Portable media players
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
Typical Application
DC/DC 1.8V
Efficiency
OUT
100
95
90
85
80
75
70
65
60
55
50
MIC2800-xxxYML
3.6V
4.2V
3V
VIN
VIN
VIN
LDO
SW
FB
VOUT
2.7V to 5.5V
Memory/DSP
Baseband
4.7µF/
6.3V
2.2µH
2.2µF
ceramic
EN1
LOWQ
EN2
CBYP
CBIAS
LDO1
LDO2
POR
CSET
L = 2.2µH
= 2.2µF
COUT2
2.2µF
ceramic
COUT1
2.2µF
ceramic
CBYP
0.01µF
C
OUT
/LowQ = V
PGND
SGND
IN
CBIAS
0.1µF
CSET
0.01µF
0
100 200 300 400 500 600
OUTPUT CURRENT (mA)
GND
GND
LOWQ is a 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
M9999-061406
(408) 955-1690
June 2006
Micrel, Inc.
MIC2800
Ordering Information
Part number
Manufacturing
Part Number
Voltage
Junction
Temperature Range
Package
MIC2800-1.8/1.2/2.8YML
MIC2800-1.87/1.2/2.8YML
MIC2800-1.8/1.5/2.8YML
MIC2800-Adj/1.2/3.3YML
Notes:
MIC2800-G4MYML
MIC2800-D24MYML
MIC2800-GFMYML
MIC2800-A4SYML
1.8V/1.2V/2.8V
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
16-Pin 3x3 MLF®
16-Pin 3x3 MLF®
16-Pin 3x3 MLF®
16-Pin 3x3 MLF®
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 VDC/DC - VDO.
LDO2 – Output Voltage Range of 0.8V to 3.6V.
M9999-061406
(408) 955-1690
June 2006
2
Micrel, Inc.
MIC2800
Pin Configuration
3mm x 3mm MLF® (ML)
Fixed DC/DC Converter Output Voltage
Pin Description
Pin Number
Pin Name
Pin Function
_____
LOWQ
LOWQ Mode. Active Low Input. Logic High = Full Power Mode; Logic Low =
LOWQ Mode; Do not leave floating.
1
Internal circuit bias supply. It must be de-coupled to signal ground with a 0.1µF
capacitor and should not be loaded.
2
BIAS
3
4
5
6
7
8
SGND
PGND
SW
VIN
VIN
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
LDO2
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
9
FB
10
11
LDO
LDO1
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
12
13
14
15
16
POR
CSET
CBYP
EN1
EN2
M9999-061406
(408) 955-1690
June 2006
3
Micrel, Inc.
MIC2800
Absolute Maximum Ratings(1)
Operating Ratings(2)
Supply Voltage (VIN)............................................. 0V to +6V
Enable Input Voltage (VEN)................................... 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
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
Conditions
Rising input voltage during turn-on
Min
2.45
Typ
2.55
100
800
Max
2.65
Units
V
mV
µA
UVLO Threshold
UVLO Hysteresis
Ground Pin Current
VFB = GND (not switching);
LDO2 Only (EN1 = LOW)
All EN = 0V
1100
55
0.2
30
85
95
5
µA
µA
µA
Ground Pin Current in
Shutdown
Ground Pin Current
(LOWQ mode)
IDC/DC < ILDO1 < ILDO2 < 10mA
DC/DC and LDO1 OFF; ILDO2 < 10mA
60
80
70
µA
µA
µA
°C
°C
20
160
23
Over-temperature Shutdown
Over-temperature Shutdown
Hysteresis
Enable Inputs (EN1; EN2; /LOWQ )
Enable Input Voltage
Logic Low
Logic High
VIL < 0.2V
VIH > 1.0V
0.2
V
V
1.0
Enable Input Current
0.1
0.1
1
1
µA
µA
Turn-on Time (See Timing Diagram)
Turn-on Time
(LDO1 and LDO2)
Turn-on Time (DC/DC)
POR Output
EN2=VIN
EN1=VIN
240
120
83
500
350
350
µs
µs
µs
EN2=VIN; ILOAD = 300mA; CBYP = 0.1µF
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)
)
90
91
96
%
%
99
VOL
POR Output Logic Low Voltage; IL = 250µA
Flag Leakage Current, Flag OFF
10
100
1
mV
µA
IPOR
0.01
SET INPUT
SET Pin Current Source
SET Pin Threshold Voltage
VSET = 0V
POR = High
0.75
1.25
1.25
1.75
µA
V
M9999-061406
(408) 955-1690
June 2006
4
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
Typ
Max
Units
LOWQ = High (Full Power Mode)
Nominal VOUT tolerance
-2
-3
0.75
+2
+3
1.6
5
%
%
A
nA
%/V
%/V
Fixed Output Voltages
Current Limit in PWM Mode
FB pin input current (ADJ only)
Output Voltage Line Regulation
VFB = 0.9*VNOM
1
1
0.2
VOUT > 2.4V; VIN = VOUT + 300mV to 5.5V, ILOAD= 100mA
V
OUT < 2.4V; VIN = 2.7V to 5.5V, ILOAD= 100mA
Output Voltage Load Regulation 20mA < ILOAD < 300mA
0.2
1.5
%
%
Maximum Duty Cycle
100
VFB ≤ 0.4V
PWM Switch ON-Resistance
ISW = 150mA VFB = 0.7VFB_NOM
0.6
0.8
2
Ω
Ω
MHz
I
SW = -150mA VFB = 1.1VFB_NOM
Oscillator Frequency
Output Voltage Noise
1.8
2.2
COUT = 2.2µF; CBYP = 0.1µF; 10Hz to 100KHz
60
µVRMS
LOWQ = Low (Light Load Mode)
Output Voltage Accuracy
Variation from nominal VOUT
Variation from nominal VOUT; -40°C to +125°C
-2.0
-3.0
+2.0
+3.0
%
%
Output Voltage Temp.
Coefficient
40
ppm/C
Line Regulation
VIN = VOUT + 1V to 5.5V; IOUT = 100µA
0.02
0.3
0.6
1.5
%/V
%/V
Load Regulation
Ripple Rejection
IOUT = 100µA to 50mA
0.2
55
45
%
dB
dB
f = up to 1kHz; COUT = 2.2µF; CBYP = 0.1µF
f = 20kHz; COUT = 2.2µF; CBYP = 0.1µF
VOUT = 0V
Current Limit
80
120
190
mA
M9999-061406
(408) 955-1690
June 2006
5
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
Typ
Max
Units
LOWQ = High (Full Power Mode)
Output Voltage Accuracy
Variation from nominal VOUT
Variation from nominal VOUT; -40°C to +125°C
VIN > 1.8V
VIN > 1.5V
IOUT = 100µA to 150mA
-2.0
-3.0
300
120
+2.0
+3.0
%
%
mA
mA
%
%
Output Current Capability
Load Regulation
0.17
0.3
500
70
44
30
1.5
I
OUT = 100µA to 300mA
Current Limit
Ripple Rejection
VOUT = 0V
350
700
mA
dB
dB
f = up to 1kHz; COUT = 2.2µF; CBYP = 0.1µF
f = 20kHz; COUT = 2.2µF; CBYP = 0.1µF
COUT = 2.2µF; CBYP = 0.1µF; 10Hz to 100KHz
Output Voltage Noise
µVRMS
LOWQ = Low (Light Load Mode)
Output Voltage Accuracy
Variation from nominal VOUT
Variation from nominal VOUT; -40°C to +125°C
IOUT = 100µA to 10mA
-3.0
-4.0
+3.0
+4.0
0.5
%
%
%
Load Regulation
0.2
1.0
%
Current Limit
Ripple Rejection
VOUT = 0V
50
85
70
42
125
mA
dB
dB
f = up to 1kHz; COUT = 2.2µF; CBYP = 0.1µF
f = 20kHz; COUT = 2.2µF; CBYP = 0.1µF
M9999-061406
(408) 955-1690
June 2006
6
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
Typ
Max
Units
LOWQ = High (Full Power Mode)
Output Voltage Accuracy
Variation from nominal VOUT
Variation from nominal VOUT; -40°C to +125°C
VIN = VOUT +1V to 5.5V; IOUT = 100µA
-2.0
-3.0
+2.0
+3.0
0.3
%
%
%/V
Line Regulation
Load Regulation
0.02
0.6
IOUT = 100µA to 150mA
0.20
0.25
0.40
70
94
142
75
40
550
25
%
%
%
mV
mV
mV
dB
dB
mA
µVRMS
I
I
OUT = 100µA to 200mA
OUT = 100µA to 300mA
1.5
Dropout Voltage
Ripple Rejection
IOUT = 150mA
IOUT = 200mA
I
OUT = 300mA
300
f = up to 1kHz; COUT = 2.2µF; CBYP = 0.1µF
f = 20kHz; COUT = 2.2µF; CBYP = 0.1µF
VOUT = 0V
Current Limit
Output Voltage Noise
400
850
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
VIN = VOUT +1V to 5.5V
-3.0
-4.0
+3.0
+4.0
0.3
%
%
%/V
Line Regulation
0.02
0.6
Load Regulation
Dropout Voltage
IOUT = 100µA to 10mA
IOUT = 10mA
0.2
22
1.0
35
50
%
mV
mV
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
dB
dB
mA
Current Limit
50
125
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.
M9999-061406
(408) 955-1690
June 2006
7
Micrel, Inc.
MIC2800
Typical Characteristics (DC/DC PWM Mode)
DC/DC 1.87V
Efficiency
DC/DC 1.8V
Efficiency
OUT
DC/DC Current Limit
vs. Temperature
OUT
100
95
90
85
80
75
70
65
60
55
50
100
95
90
85
80
75
70
65
60
55
50
1400
1200
1000
800
600
400
200
0
3.6V
3V
3V
3.6V
4.2V
4.2V
C
C
= 2.2µF
= 0.1µF
OUT
BYP
L = 2.2µH
OUT
/LowQ = V
L = 2.2µH
= 2.2µF
C
= 2.2µF
C
/LowQ = V
OUT
/LowQ = V
IN
EN1 = EN2 = V
IN
IN
IN
20 40 60 80
TEMPERATURE (°C)
0
100 200 300 400 500 600
OUTPUT CURRENT (mA)
0
100 200 300 400 500 600
OUTPUT CURRENT (mA)
DC/DC Enable Threshold
vs. Supply Voltage
DC/DC Turn-On Delay
vs. Supply Voltage
1000
950
900
850
800
750
700
650
600
550
500
100
95
90
85
80
75
70
65
60
55
50
ON
OFF
C
OUT
= 2.2µF
C
= 2.2µF
OUT
/LowQ = V
/LowQ = V
IN
IN
2.7
3.4
4.1
4.8
5.5
2.7 3.2 3.7 4.2 4.7 5.2
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
M9999-061406
(408) 955-1690
June 2006
8
Micrel, Inc.
MIC2800
Typical Characteristics (DC/DC LowQ Mode)
Power Supply Rejection Ratio
(Input Voltage)
Power Supply Rejection Ratio
LDO Current Limit
vs. Supply Voltage
(Output Current)
60
80
70
60
50
40
30
100
80
60
40
20
0
4.2V
0µA
50
40
30
20
10
0
3.6V
100µA
50mA
I
V
C
= 50mA
= 1.8V
= 2.2µF
V
= 3.6V
OUT
OUT
OUT
20 IN
V
= 1.8V
OUT
10
0
C
= 2.2µF
C
OUT
= 2.2µF
OUT
/LowQ = GND
/LowQ = GND
/LowQ = GND
4.8 5.5
SUPPLY VOLTAGE (V)
0.01 0.1
1
10
100 1,000
0.01 0.1
1
10
100 1,000
2.7
3.4
4.1
FREQUENCY (kHz)
FREQUENCY (kHz)
LDO Output Voltage
vs. Output Current
DC/DC LowQ Mode
Output Noise Spectral Density
1.90
1.89
1.88
1.87
1.86
1.85
1.84
10
1
0.1
V
V
C
= 4.2V
IN
OUT
OUT
V
V
= 3.6V
0.01
IN
OUT
C
= 1.87V
= 2.2µF
= 1.87V
= 2.2µF
OUT
/LowQ = GND
/LowQ = GND
0.001
0.01 0.1
1
10 100 1,000 10,000
10 20 30 40 50 60 70 80 90
OUTPUT CURRENT (mA)
FREQUENCY (kHz)
M9999-061406
(408) 955-1690
June 2006
9
Micrel, Inc.
MIC2800
Typical Characteristics (LDO1, LDO2)
Power Supply Rejection Ratio
(LDO1 LowQ Mode)
Power Supply Rejection Ratio
Power Supply Rejection Ratio
(LDO1 Normal Mode)
(LDO2 LowQ Mode)
100
80
70
60
50
40
30
20
-90
-80
-70
-60
-50
-40
50mA
10mA
90
80
70
60
50
40
30
20
10
0
50mA
50mA
100µA
100µA
100µA
150mA
V
V
= 4.2V
V
V
= 4.2V
-30 V = 4.2V
IN
IN
OUT
C
IN
OUT
OUT
= 1.2V
= 2.2µF
/LowQ = GND
= 0.1µF
= 1.2V
= 2.2µF
V
= 2.8V
OUT
-20
-10
0
C
C = 2.2µF
OUT
OUT
10 /LowQ = V
/LowQ = V
C = 0.01µF
IN
IN
C
C
= 0.1µF
BYP
BYP
BYP
0
0.01 0.1
1
10
100 1,000
0.01 0.1
1
10
100 1,000
0.01 0.1
1
10
100 1,000
FREQUENCY (kHz)
FREQUENCY (kHz)
FREQUENCY (kHz)
Power Supply Rejection Ratio
(LDO2 Normal Mode)
(LDO2) Output Voltage
vs. Temperature
Ground Current
vs. Temperature
100
90
80
70
60
50
40
30
20
10
0
3.00
2.95
2.90
2.85
2.80
2.75
2.70
2.65
2.60
2.55
2.50
70
65
60
55
50
45
40
35
30
100µA
300mA
100µA
300mA
150mA
50mA
V
V
C
C
= V
+ 1V
IN
OUT
100mA
V
V
C
C
= V
+ 1V
OUT
= 2.8V
IN
OUT
= 2.8V
= 2.2µF
= 0.1µF
V
V
= 4.2V
OUT
OUT
IN
OUT
C
= 2.2µF
= 0.1µF
= 1.2V
= 2.2µF
OUT
BYP
BYP
/LowQ = V
IN
OUT
EN1 = GND
EN2 = V
EN1 = GND
/LowQ = V
C
IN
EN2 = V
= 0.01µF
IN
IN
BYP
20 40 60 80
0.01 0.1
1
10
100 1,000
20 40 60 80
TEMPERATURE (°C)
FREQUENCY (kHz)
TEMPERATURE (°C)
Ground Current
vs. Output Current
(LDO2) Dropout Voltage
vs. Output Current
(LDO2) Dropout Voltage
vs. Temperature
70
60
50
40
30
140
120
100
80
0.20
0.18
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0.00
V
C
C
= 2.8V
= 2.2µF
= 0.1µF
OUT
OUT
BYP
300mA
/LowQ = V
IN
150mA
100mA
60
40
V
V
C
C
= 2.8V
IN
OUT
V
C
C
= 2.8V
= 2.2µF
= 0.1µF
OUT
OUT
BYP
= 2.8V
50mA
= 2.2µF
= 0.1µF
20
OUT
BYP
20mA
/LowQ = V
IN
0
20 40 60 80
TEMPERATURE (°C)
0
50 100 150 200 250 300
OUTPUT CURRENT (mA)
0
50 100 150 200 250 300
OUTPUT CURRENT (mA)
Dropout Chararcteristics
LDO1 Output Noise
Spectral Density
LDO2 Output Noise
Spectral Density
3.0
2.5
2.0
10
1
10
1
C
C
= 2.2µF
= 0.1µF
OUT
BYP
/LowQ = V
IN
100mA
150mA
300mA
0.1
0.1
V
V
C
C
= 4.2V
V
V
C
C
= 4.2V
IN
IN
= 1.2V
= 2.8V
OUT
OUT
BYP
OUT
OUT
BYP
0.01
0.01
= 2.2µF
= 0.1µF
= 2.2µF
= 0.1µF
/LowQ = V
/LowQ = V
IN
IN
0.001
0.001
0.01 0.1
1
10 100 1,000 10,000
0.01 0.1
1
10 100 1,000 10,000
1.5
2.0
2.5
3.0
3.5
FREQUENCY (kHz)
FREQUENCY (kHz)
SUPPLY VOLTAGE (V)
M9999-061406
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June 2006
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Micrel, Inc.
MIC2800
Functional Characteristics
DC/DC Load Transient PWM Mode
DC/DC Line Transient PWM Mode
V
V
= V
+ 1V
OUT
IN
= 1.8V
OUT
C
C
= 2.2µF
= 0.01µF
OUT
BYP
/LowQ = V
IN
V
V
= V
+ 1V
OUT
IN
= 1.87V
= 2.2µF
= 0.01µF
OUT
C
C
OUT
BYP
/LowQ = V
IN
= 100mA
400mA
I
OUT
10mA
Time (20µs/div)
Time (20µs/div)
Enable Transient PWM Mode
V
V
= 3.6V
IN
= 1.8V
OUT
C
C
= 2.2µF
= 0.01µF
OUT
BYP
/LowQ = V
IN
I
= 300mA
OUT
Time (40µs/div)
M9999-061406
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June 2006
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Micrel, Inc.
MIC2800
Functional Characteristics
DC/DC Load Transient LowQ Mode
DC/DC Line Transient LowQ Mode
V
V
= V
+ 1V
OUT
IN
= 1.8V
OUT
50mA
C
C
= 2.2µF
= 0.01µF
OUT
BYP
V
V
= V
+ 1V
OUT
/LowQ = GND
IN
= 1.87V
= 2.2µF
= 0.01µF
OUT
C
C
OUT
100µA
BYP
/LowQ = GND
= 10mA
I
OUT
Time (20µs/div)
Time (10µs/div)
Enable Transient LowQ Mode
V
V
= EN1 = 3.8V
IN
= 1.8V
OUT
C
C
= 2.2µF
= 0.01µF
OUT
BYP
/LowQ = GND
= 100µA
I
OUT
Time (20µs/div)
M9999-061406
(408) 955-1690
June 2006
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Micrel, Inc.
MIC2800
Functional Characteristics
LDO2 Load Transient Normal Mode
LDO2 Load Transient LowQ Mode
V
V
= V
+ 1V
OUT
V
V
= 3.6V
IN
IN
= 2.8V
= 2.8V
OUT
OUT
C
C
= 2.2µF
= 0.01µF
C
C
= 2.2µF
= 0.01µF
OUT
BYP
OUT
300mA
BYP
50mA
/LowQ = GND
/LowQ = V
IN
100µA
100µA
Time (200µs/div)
Time (4µs/div)
LDO2 Line Transient Normal Mode
LDO2 Line Transient LowQ Mode
5.5V
5.5V
V
V
= V
+ 1V
OUT
V
V
= V
+ 1V
OUT
IN
IN
4V
4V
= 1.87V
= 2.2µF
= 0.01µF
= 1.87V
= 2.2µF
= 0.01µF
OUT
OUT
C
C
C
C
OUT
OUT
BYP
BYP
/LowQ = V
IN
/LowQ = GND
= 10mA
I
= 100mA
I
OUT
OUT
Time (40µs/div)
Time (20µs/div)
M9999-061406
(408) 955-1690
June 2006
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Micrel, Inc.
MIC2800
Functional Characteristics
DC/DC LowQ Mode to PWM Mode Transition
DC/DC PWM Mode to LowQ Mode Transition
V
V
= V
+ 1V
OUT
IN
= 1.8V
V
V
= V
+ 1V
OUT
OUT
IN
C
C
I
= 2.2µF
= 0.01µF
= 1.8V
OUT
BYP
OUT
C
C
= 2.2µF
= 0.01µF
OUT
= 50mA
OUT
BYP
I
= 100µA
OUT
Time (100µs/div)
Time (100µs/div)
DC/DC PWM Waveform
V
V
C
= 4V
C
= 0.01µF
BYP
IN
= 1.8V
/LowQ = V
L = 2.2µH
OUT
IN
= 2.2µF
OUT
Time (400µs/div)
M9999-061406
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June 2006
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Micrel, Inc.
MIC2800
Functional Characteristics
ESR vs. Load
ESR vs. Load
LDO1
LDO
100
10
1
100
10
1
STABLE AREA
STABLE AREA
0.1
0.1
0
50
100
150
0
50
100
150
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
ESR vs. Load
LDO2
100
10
1
STABLE AREA
0.1
0
50
100
150
OUTPUT CURRENT (mA)
M9999-061406
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June 2006
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Micrel, Inc.
MIC2800
Functional Diagram
VIN
VIN
CBIAS
LDO
DC to DC
SW
FB
EN1
_____
LOWQ
LDO1
LDO2
VOUT1
VOUT2
EN2
Reference and
Quick Start
POR
POR
CBYP
PGND
CSET
SGND
MIC2800 Fixed Block Diagram
M9999-061406
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June 2006
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Micrel, Inc.
MIC2800
LDO1
Application Notes
Regulated output voltage of LDO1. Power is provided by
the DCDC switching regulator. Recommended output
capacitance is 2.2µF.
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.
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.
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.
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.
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.
/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.
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.
/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 6ꢀ resistor. A small 0.1µF capacitor
is recommended for bypassing.
M9999-061406
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June 2006
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Micrel, Inc.
FB
MIC2800
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
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.
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.
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.
⎛
⎞
VOUT
⎜
⎟
⎟
VOUT 1−
⎜
V
IN
⎝
⎠
IPK = IOUT
+
2× f ×L
Output Capacitor
LDO1 and LDO2 outputs require a 2.2µF ceramic output
capacitor for stability. The DC/DC switch mode regulator
M9999-061406
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June 2006
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Micrel, Inc.
MIC2800
PCB Layout
Top Layer
M9999-061406
(408) 955-1690
June 2006
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Micrel, Inc.
MIC2800
Bottom Layer
M9999-061406
(408) 955-1690
June 2006
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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.
M9999-061406
(408) 955-1690
June 2006
21
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