MICREL MIC2810

MIC2810
Digital Power Management IC
2MHz, 600mA DC/DC w/Dual
300mA/300mA Low VIN LDOs
General Description
The MIC2810 is a high performance power management
IC, integrating a 2MHz DC/DC switcher with two 300mA
LDOs. The MIC2810 features a LOWQ® mode, reducing
the total current draw while in this mode to less than 30µA.
In LOWQ® mode, the output noise of the DC/DC converter
is 53µVRMS, significantly lower than other converters that
use a PFM light load mode that can interfere with sensitive
RF circuitry.
The MIC2810 is a µCap design, operating with very small
ceramic output capacitors and inductors for stability,
therefore, reducing required board space and component
cost. It is available with fixed output voltages in a 16-pin
3mm x 3mm MLF® leadless package.
Data sheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
Features
• 2MHz DC/DC converter and two LDOs
• Integrated power-on reset (OR function for all outputs)
– Adjustable delay time
• LOWQ® mode
– 30µA Total IQ when in LOWQ® mode
• Tiny 16-pin 3mm x 3mm MLF® package
• Thermal shutdown protection
• Current limit protection
DC/DC Converter
• 2.7V to 5.5V input voltage range
• Output current to 600mA in PWM mode
• LOWQ® Mode: NO NOISE light load mode
– 53µVRMS Output noise in LOWQ® mode
• 2MHz PWM operation in normal mode
LDOs
• LDO1
– 1.65V to 5.5V input voltage range
– 300mA Output current
– Output voltage down to 0.8V
• LDO2
– 2.7V to 5.5V input voltage range
– 300mA Output current
– Output voltage down to 0.8V
Applications
•
•
•
•
•
Mobile phones
PDAs
GPS receivers
Digital still cameras
Portable media players
Typical Application
1.2VOUT Efficiency
90
MIC2810-xxxYML
VIN
2.7V to 5.5V
4.7µF
VIN
VIN1
VIN2
EN
EN1
LOWQ
EN2
BIAS
PGND
0.1µF
LDO
SW
VOUT
2.2µH
80
Memory/DSP
70
2.2µF
60
LDO1
LDO2
POR
CSET
SGND
50
Baseband
2.2µF
ceramic
VIN=4.2V
40
2.2µF
ceramic
30
20
0.01µF
GND
VIN=3V
VIN=3.6V
GND
10
0
100 200 300 400 500 600
OUTPUT CURRENT (mA)
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
February 2008
M9999-022008-C
Micrel, Inc.
MIC2810
Ordering Information
Part Number
Marking
Code
Voltage*
Junction
Temperature Range
Package
MIC2810-44MYML
YD44M
1.2V/1.2V/2.8V
–40°C to +125°C
16-Pin 3x3 MLF®
Pb-Free
–40°C to +125°C
16-Pin 3x3 MLF
®
Pb-Free
®
Pb-Free
MIC2810-4GKYML
YD4GK
1.2V/1.8V/2.6V
Lead Finish
MIC2810-4GMYML
YD4GM
1.2V/1.8V/2.8V
–40°C to +125°C
16-Pin 3x3 MLF
MIC2810-4GPYML
YD4GP
1.2V/1.8V/3.0V
–40°C to +125°C
16-Pin 3x3 MLF®
Pb-Free
–40°C to +125°C
16-Pin 3x3 MLF
®
Pb-Free
®
Pb-Free
MIC2810-4GSYML
YD4GS
1.2V/1.8V/3.3V
MIC2810-4LSYML
YD4LS
1.2V/2.7V/3.3V
–40°C to +125°C
16-Pin 3x3 MLF
MIC2810-4MSYML
YD4MS
1.2V/2.8V/3.3V
–40°C to +125°C
16-Pin 3x3 MLF®
Pb-Free
–40°C to +125°C
16-Pin 3x3 MLF
®
Pb-Free
16-Pin 3x3 MLF
®
Pb-Free
MIC2810-CGJYML
MIC2810-FGSYML
YDCGJ
YDFGS
1.2V/1.8V/2.5V
1.5V/1.8V/3.3V
–40°C to +125°C
Notes:
MLF® is a GREEN RoHS compliant package. Lead finish is NiPdAu. Mold compound is Halogen Free.
Other voltage options available. Please contact Micrel for details.
DC/DC –Output Voltage Range of 1.0V to 2.0V.
LDO1 – Output Voltage Range of 0.8V to 3.6V.
LDO2 – Output Voltage Range of 0.8V to 3.6V.
* Refers to nominal output voltage of DC/DC, LDO1, and LDO2 respectively.
February 2008
2
M9999-022008-C
Micrel, Inc.
MIC2810
Pin Configuration
®
16-Pin 3mm x 3mm MLF (ML)
Pin Description
Pin Number
Pin Name
1
/LOWQ
2
BIAS
3
4
5
SGND
PGND
SW
6
VIN
7
8
9
10
11
VIN2
LDO2
LDO
VIN1
LDO1
12
POR
13
CSET
14
EN1
15
EN
16
EN2
February 2008
Pin Function
LOWQ Mode. Active Low Input. Logic High = Full Power (Normal) 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: Internal power MOSFET output switches.
Supply Input – DC/DC and other circuitry shared with LDO1 and LDO2. Must be
connected to PIN 7.
Supply Input – LDO2. Must be connected to PIN 6.
Output of LDO2
LDO Output: Connect to VOUT of the DC/DC for LOWQ mode operation.
Supply Input – LDO1.
Output of LDO1
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.
Enable Input (LDO 1). Active High Input. Logic High = On; Logic Low = Off; Do not
leave floating
Enable Input (DC/DC). 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
M9999-022008-C
Micrel, Inc.
MIC2810
Absolute Maximum Ratings(1)
Operating Ratings(2)
Supply Voltage (VIN, VIN1, VIN2)............................... 0V to 6V
Enable Input Voltage (VEN, VEN1, VEN2)................... 0V to VIN
Power Dissipation .................................. Internally Limited(3)
Lead Temperature (soldering, 10 sec.)...................... 260°C
Storage Temperature (Ts) .........................–65°C to +150°C
ESD Rating(4) .................................................................. 2kV
Supply Voltage (VIN, VIN2)................................. 2.7V to 5.5V
Supply Voltage (VIN1)...................................... 1.65V to 5.5V
Enable Input Voltage (VEN, VEN1, VEN2)................... 0V to VIN
Junction Temperature (TJ) ........................ –40°C to +125°C
Junction Thermal Resistance
MLF-16 (θJA) ......................................................56°C/W
Electrical Characteristics(5)
VIN = VIN1 = VIN2 = EN1 = EN2 = EN = /LOWQ = VOUT(6) + 1V; COUTDC/DC = 2.2µF, CLDO1 = CLDO2 = 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
LDO1 or LDO2 (EN = GND; EN1 or EN2 = GND)
55
EN = EN1 = EN2 = 0V
0.2
IDC/DC < ILDO1 < ILDO2 < 10mA (/LOWQ = GND)
38
LDO1 or LDO2 (EN = GND; EN1 or EN2 = GND);
IOUT < 10mA (/LOWQ = GND)
20
Over-temperature Shutdown
Over-temperature Shutdown
Hysteresis
Enable Inputs (EN; EN1; EN2; /LOWQ )
Enable Input Voltage
Logic Low
Logic High
Enable Input Current
VIL < 0.2V
VIH > 1.0V
Turn-on Time
Turn-on Time
(LDO1 and LDO2)
Turn-on Time (DC/DC)
(/LOWQ = VIN; ILOAD = 300mA); (/LOWQ = GND; ILOAD =
10mA)
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
February 2008
Min
2.45
4
Max
2.65
1100
Units
V
mV
µA
85
95
5
µA
µA
µA
60
80
70
µA
µA
µA
°C
°C
160
23
0.2
0.1
0.1
1
1
V
V
µA
µA
240
500
µs
83
350
µs
1.0
90
0.75
91
%
96
99
%
10
0.01
100
1
mV
µA
1.25
1.25
1.75
µA
V
M9999-022008-C
Micrel, Inc.
MIC2810
Electrical Characteristics - DC/DC Converter
VIN = VOUTDC/DC + 1; EN = VIN; EN2 = EN1 = 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)
Fixed Output Voltages
Output Voltage Line Regulation
Output Voltage Load Regulation
Maximum Duty Cycle
PWM Switch ON-Resistance
Oscillator Frequency
Current Limit in PWM Mode
Nominal VOUT tolerance
–2
–3
VOUT > 2.4V; VIN = VOUT + 300mV to 5.5V, ILOAD= 100mA
VOUT < 2.4V; VIN = 2.7V to 5.5V, ILOAD= 100mA
20mA < ILOAD < 600mA
VFB ≤ 0.4V
ISW = 150mA VFB = 0.7VFB_NOM PMOS
ISW = -150mA VFB = 1.1VFB_NOM NMOS
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; IOUT = 100µA
Load Regulation
Ripple Rejection
Current Limit
IOUT = 100µA to 50mA
f = up to 1kHz
VOUT = 0V
Output Voltage Noise
10Hz to 100KHz
February 2008
%/V
0.1
%
%
Ω
Ω
MHz
A
0.5
0.6
2
1
–2
–3
0.02
80
0.4
45
120
53
5
%
%
0.2
100
1.8
0.75
VFB = 0.9*VNOM
+2
+3
2.2
1.6
+2
+3
0.3
0.6
1.5
220
%
%
%/V
%/V
%
dB
mA
µVRMS
M9999-022008-C
Micrel, Inc.
MIC2810
Electrical Characteristics – LDO1/LDO2
VIN1 = VIN2 = VOUTLDO1 + 1.0V or VIN1 = VIN2 = VOUTLDO2 + 1.0V; EN = GND; EN1 = EN2 = VIN1 = VIN2; CLDO1 = CLDO2 = 2.2µF;
IOUTLDO1 = 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
–2
–3
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
VOUT = 0V
10Hz to 100kHz
Load Regulation
Dropout Voltage
IOUT = 100µA to 10mA
IOUT = 10mA
Ripple Rejection
Current Limit
f = up to 1kHz
VIN = 2.7V; VOUT = 0V
0.02
400
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
0.20
0.25
0.40
70
94
142
35
600
91
–3
–4
0.02
0.2
22
50
35
85
Max
Units
+2
+3
0.3
0.6
%
%
%/V
1.5
300
850
+3
+4
0.3
0.6
1.0
35
50
125
%
%
%
mV
mV
mV
dB
mA
µVRMS
%
%
%/V
%
mV
mV
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.
February 2008
6
M9999-022008-C
Micrel, Inc.
MIC2810
Typical Characteristics ― DC/DC Normal Mode (/LOWQ = VIN)
1.2VOUT Efficiency
90
2.4
80
2.3
70
60
50
VIN=3V
2.2
VIN=3.6V
2.1
VIN=4.2V
2.0
40
1.9
30
1.8
20
10
0
Switching Frequency
vs. Input Voltage
100 200 300 400 500 600
OUTPUT CURRENT (mA)
L = 2.2µH
COUT = 2.2µF
IOUT = 300mA
/LowQ = VIN
1.7
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
INPUT CURRENT (V)
Load Regulation
Switching Frequency
vs. Temperature
2.4
2.3
2.2
2.1
2.0
1.9
1.8
1.7
1.6
VIN = 3.6V
1.5
IOUT = 400mA
1.4
/LowQ = VIN
1.3
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
Line Regulation
1.22
1.200
1.21
1.198
1.20
1.196
1.8
Current Limit
vs. Input Voltage
1.6
L = 2.2µH
COUT = 2.2µF
VIN = 3.6V
/LowQ = VIN
1.19
1.18
0
100 200 300 400 500 600
OUTPUT CURRENT (mA)
February 2008
1.194
1.4
1.2
1.0
L = 2.2µH
COUT = 2.2µF
IOUT = 300mA
/LowQ = VIN
1.192
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
INPUT VOLTAGE (V)
7
0.8
0.6
/LowQ = VIN
0.4
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
INPUT VOLTAGE (V)
M9999-022008-C
Micrel, Inc.
MIC2810
Typical Characteristics ― DC/DC LOWQ Mode (/LOWQ = GND)
80
Power Supply
Rejection Ratio
Load Regulation
1.24
70
1.23
60
1.22
50
1.21
40
1.20
30
1.19
VIN = 3.6V
20 VOUT = 1.2V
COUT = 2.2µF
10 IOUT = 5mA
/LowQ = GND
0
0.01 0.1
1
10
100
FREQUENCY (kHz)
380
1.18
1.17
1000
Current Limit
vs. Input Voltage
1.16
0
10
Line Regulation
1.30
1.25
1.20
COUT = 2.2µF
VIN = 3.6V
/LowQ = GND
10 20 30 40 50 60 70 80
OUTPUT CURRENT (mA)
1.15
COUT = 2.2µF
VIN = 3.6V
IOUT = 20mA
/LowQ = GND
1.10
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
INPUT VOLTAGE (V)
Output Noise
Spectral Density
340
300
1
260
220
180
0.1
140
100
60
/LowQ = GND
20
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
INPUT VOLTAGE (V)
February 2008
0.01 VIN = 4.2V
VOUT = 1.2V
COUT = 2.2µF
/LowQ = GND
0.001
0.01 0.1
1
10 100 1,000 10,000
FREQUENCY (kHz)
8
M9999-022008-C
Micrel, Inc.
MIC2810
Typical Characteristics ― LDO1/LDO2
Power Supply Rejection Ratio
LDO1[LOWQ Mode]
80
VIN = 3.6V
VOUT = 1.2V
COUT = 2.2µF
IOUT = 25mA
/LowQ = GND
70
60
50
70
60
50
20
20
2.0
1.9
1.7
10
10
0.1
1
10
100
FREQUENCY (kHz)
1000
Power Supply Rejection Ratio
LDO2[LOWQ Mode]
90
VIN = 3.6V
VOUT = 2.8V
COUT = 2.2µF
IOUT = 25mA
/LowQ = GND
80
70
60
50
0
0.01
0.1
1
10
100
FREQUENCY (kHz)
1000
Power Supply Rejection Ratio
LDO2[Normal Mode]
80
70
60
50
VIN = 3.6V
VOUT = 2.8V
COUT = 2.2µF
IOUT = 100mA
/LowQ = VIN
COUT = 2.2µF
VIN = 3.6V
IOUT = 150mA
/LowQ = VIN
1.6
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
INPUT VOLTAGE (V)
LDO2 Load Regulation
2.85
2.80
40
40
30
30
20
20
10
10
80
LDO1 Line Regulation
1.8
30
30
0
0.01
VIN = 3.6V
VOUT = 1.2V
COUT = 2.2µF
IOUT = 100mA
/LowQ = VIN
40
40
0
0.01
Power Supply Rejection Ratio
LDO1[Normal Mode]
0.1
1
10
100
FREQUENCY (kHz)
1000
LDO2 Ground Current
vs. Output Current
0
0.01
80
2.75
0.1
1
10
100
FREQUENCY (kHz)
1000
LDO2 Ground Current
vs. Temperature
2.70
0
140
COUT = 2.2µF
VIN = 3.6V
/LowQ = VIN
50 100 150 200 250 300
OUTPUT CURRENT (mA)
LDO2 Dropout Voltage
vs. Output Current
120
75
70
70
60
80
65
50
60
100
40
60
55
0
110
VIN = 3.6V
VOUT = 2.8V
/LowQ = VIN
50 100 150 200 250 300
OUTPUT CURRENT (mA)
LDO2 Dropout Voltage
vs. Temperature
100
VIN = 3.6V
IOUT = 200mA
/LowQ = VIN
40
30
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
10
20
0
0
VOUT = 2.8V
/LowQ = VIN
50 100 150 200 250 300
OUTPUT CURRENT (mA)
LDO2 Output Noise
Spectral Density
1
90
0.1
80
70
VOUT = 2.8V
IOUT = 200mA
/LowQ = VIN
60
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
February 2008
0.01 VIN = 4.2V
VOUT = 2.8V
COUT = 2.2µF
/LowQ = VIN
0.001
0.01 0.1
1
10 100 1,000 10,000
FREQUENCY (kHz)
9
M9999-022008-C
Micrel, Inc.
MIC2810
Functional Characteristics
LDO2[LOWQ Mode] Load Transient
VIN = 3.6V
VOUT = 2.8V
COUT = 2.2µF
/LowQ = VIN
Output Voltage
AC Coupled
(50mV/div)
Output Voltage
AC Coupled
(50mV/div)
LDO2[Normal Mode] Load Transient
200mA
1mA
Output Current
DC Coupled
(100mA/div)
VIN = 3.6V
VOUT = 2.8V
COUT = 2.2µF
/LowQ = GND
Time (40µs/div)
DC/DC[LOWQ Mode] Load Transient
DC/DC[LOWQ Mode] Start-Up Waveforms
Enable Voltage
DC Coupled
(2V/div)
VIN = 3.6V
VOUT = 1.2V
COUT = 2.2µF
/LowQ = GND
1mA
VIN = 3.6V
VOUT = 1.2V
COUT = 2.2µF
/LowQ = GND
IOUT = 20mA
Output Voltage
DC Coupled
(500mV/div)
Output Current
DC Coupled
(20mA/div)
50mA
Time (20µs/div)
Time (40µs/div)
February 2008
10mA
Time (100µs/div)
Output Voltage
AC Coupled
(20mV/div)
Output Current
DC Coupled
(20mA/div)
45mA
10
M9999-022008-C
Micrel, Inc.
MIC2810
Functional Characteristics (cont.)
L = 2.2µH
/LowQ = VIN
IOUT = 300mA
Output Voltage
AC Coupled
(50mV/div)
VIN = 3.6V
VOUT = 1.2V
COUT = 2.2µF
DC/DC Load Transient
Switch Voltage Inductor Current
DC Coupled
DC Coupled
(200mA/div)
(2V/div)
Output Voltage
AC Coupled
(20mV/div)
DC/DC PWM Waveforms
Output Current
DC Coupled
(200mA/div)
300mA
VIN = 3.6V
VOUT = 1.2V
COUT = 2.2µF
L = 2.2µH
/LowQ = VIN
10mA
Time (20µs/div)
Time (400ns/div)
Enable Voltage
DC Coupled
(2V/div)
DC/DC Start-Up Waveforms
Output Voltage
DC Coupled
(500mV/div)
VIN = 3.6V
VOUT = 1.2V
COUT = 2.2µF
L = 2.2µH
/LowQ = VIN
IOUT = 300mA
Time (20µs/div)
February 2008
11
M9999-022008-C
Micrel, Inc.
MIC2810
Functional Diagram
MIC2810 Block Diagram
February 2008
12
M9999-022008-C
Micrel, Inc.
MIC2810
LDO1
Regulated output voltage of LDO1. Power is provided by
VIN1. Recommended output capacitance is 2.2µF.
Device Functional Description
The MIC2810 is a power management IC with a single
integrated step-down regulator and two low dropout
regulators. LDO1 and LDO2 are 300mA low dropout
regulators supplied from the input voltage pins. The
step-down regulator is a 600mA PWM power supply. All
three regulators utilize a /LOWQ light load mode to
maximize battery efficiency under light load conditions.
This is achieved with a /LOWQ control pin that when
pulled low shuts down all the biasing and drive current
for the PWM regulator, along with reducing the current
limit of the two independent LDOs. When the /LOWQ pin
is pulled low, the MIC2810 draws only 30µA of operating
current. This mode allows the output to be regulated
through the LDO output which is capable of providing
60mA of output current. This method has the advantage
of producing a clean, low current, ultra-low noise output
in /LOWQ mode. During /LOWQ mode, the SW node
becomes high impedance, blocking current flow. Other
methods of reducing quiescent current, such as pulse
frequency modulation (PFM) or bursting techniques
create large amplitude and low frequency ripple voltages
that can be detrimental to system operation.
When more than 60mA is required, the /LOWQ pin can
be forced high, causing the MIC2810 to enter PWM
mode. In this case, the LDO output makes a "hand-off"
to the PWM regulator with virtually no variation in output
voltage. The LDO output then turns off allowing up to
600mA of current to be efficiently supplied through the
PWM output to the load.
LDO2
Regulated output voltage of LDO2. Power is provided by
VIN2. Recommended output capacitance is 2.2µF.
EN/EN1/EN2
All enable inputs are active high, requiring 1.0V for
guaranteed operation. EN provides logic control for the
DC/DC regulator. EN2 provides logic control for LDO2,
and EN1 provides logic control for LDO1. The enable
inputs are CMOS logic and cannot be left floating.
The enable pins provide logic level control of the
specified outputs. When all enable pins are in the off
state, supply current of the device is greatly reduced
(typically <1µA). When the DC/DC regulator is in the off
state, the output drive is placed in a "tri-stated" condition,
where both the high side P-channel MOSFET and the
low-side N-channel are in an “off” or non-conducting
state. Do not drive any of the enable pins above the
supply voltage.
Power-On Reset (POR)
The power-on reset output is an open-drain N-Channel
device, requiring a pull-up resistor to either the input
voltage or output voltage for proper voltage levels. The
POR output has a delay time that is programmable with
a capacitor from the CSET pin to ground. The delay time
can be programmed to be as long as 1 second.
Pin Functional Description
/LOWQ
The /LOWQ pin provides a logic level control between
the internal PWM switching regulator mode, and the low
noise linear regulator mode. With /LOWQ pulled low
(≤0.2V), quiescent current of the device is greatly
reduced by switching to a low noise linear regulator
mode that has a typical supply current of 38µA. In linear
(LDO) mode the output can deliver 60mA of current to
the output. By placing /LOWQ high (≥1V), the device
transitions into a constant frequency PWM step-down
regulator mode. This allows the device the ability to
efficiently deliver up to 600mA of output current at the
same output voltage.
/LOWQ mode also limits the output load of both LDO1
and LDO2 to <50mA.
VIN/VIN1/VIN2
Three input voltage pins provide power to the switch
mode regulator, LDO1, and LDO2. VIN provides power
to the control circuitry of the DC/DC converter and
voltage reference circuitry shared by all the regulators in
the MIC2810. LDO1’s input voltage (VIN1) can go down
to 1.65V but LDO2 and the DC/DC converter input
voltages are limited to 2.7V minimum.
For the switch mode regulator VIN provides power to the
MOSFET along with current limiting sense circuitry. Due
to the high switching speeds, a 4.7µF capacitor is
recommended close to VIN and the power ground
(PGND) pin for bypassing. Please refer to the PCB
layout section for an example of an appropriate circuit
layout.
BIAS
The BIAS pin supplies the power to the internal control
and reference circuitry. The bias is powered from VIN
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 of the step-down
PWM regulator. In /LOWQ mode (/LOWQ <0.2V), the
LDO provides the output voltage of the DC/DC regulator.
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Micrel, Inc.
MIC2810
Input Capacitor
A minimum 1µF ceramic, 4.7µF recommended, should
be placed as close as possible to the VIN pin for optimal
bypassing. X5R or X7R dielectrics are recommended for
the input capacitor. Y5V dielectrics lose most of their
capacitance over temperature and are therefore, not
recommended. A minimum 1µF is recommended close
to the VIN and PGND pins for high frequency filtering.
Smaller case size capacitors are recommended due to
their lower ESR and ESL. Please refer to the PCB layout
section for an example of an appropriate circuit layout.
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.
Inductor Selection
The MIC2810 is designed for use with a 2.2µH inductor.
Proper selection should ensure the inductor can handle
the maximum average and peak currents required by the
load. Maximum current ratings of the inductor are
generally given in two methods; permissible DC current
and saturation current. Permissible DC current can be
rated either for a 40°C temperature rise or a 10% to 20%
loss in inductance. Ensure that the inductor selected can
handle the maximum operating current. When saturation
current is specified, make sure that there is enough
margin that the peak current will not saturate the
inductor. Peak inductor current can be calculated as
follows:
SGND
Signal ground (SGND) is the ground path for the biasing
and control circuitry. The current loop for the signal
ground should be as small as possible.
CSET
The CSET pin is a current source output that charges a
capacitor that sets the delay time for the power-on reset
output from low to high. The delay for POR high to low
(detecting an undervoltage on any of the outputs) is
always minimal. The current source of 1.25µA charges a
capacitor up from 0V. When the capacitor reaches
1.25V, the output of the POR is allowed to go high. The
delay time in microseconds is equal to the Cset in
picofarads.
POR Delay (µs) = CSET (pF)
Component Selection
IPK:
IOUT:
VIN:
VOUT:
f:
L:
Output Capacitor
LDO1 and LDO2 outputs require a 2.2µF ceramic output
capacitor for stability. The DC/DC switch mode regulator
also requires a 2.2µF ceramic output capacitor to be
stable. All output capacitor values can be increased to
improve transient response, but performance has been
optimized for a 2.2µF ceramic on the LDOs and the
DC/DC regulator. X7R/X5R dielectric-type ceramic
capacitors are recommended because of their
temperature performance. X5R/X7R-type capacitors
change capacitance by 15% over their operating
temperature range and are the most stable type of
ceramic capacitors. Z5U and Y5V dielectric capacitors
change value by as much as 50% to 60% respectively
over their operating temperature ranges.
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⎛
⎞
V
VOUT ⎜⎜1 − OUT ⎟⎟
VIN ⎠
⎝
IPK = IOUT +
2× f ×L
Peak Inductor Current
Output/Load Current
Input Voltage
Output Voltage
Switching Frequency of PWM Regulator
Inductor Value
M9999-022008-C
Micrel, Inc.
MIC2810
PCB Layout
R3
Vin
EN1
J10
R2
EN
J9
R4
13
1 /LowQ
2
JP1
C5
POR
LDO1
BIAS
3 SGND
5
C7
GND
J7
L1 VIN
J1
LDO2
VIN2
VIN
6
7
Vin
POR
J8
C3
LD01
J4
11
LDO
SW
VO
J6
12
10
VIN1
9
4 PGND
Vo
R1
C4
CSET
EN2
/LowQ
J12
14
EN
16 15
EN1
EN2
J11
R5
Vin
Vin
Vo
C2
LD0
J3
8
C6
C1
LD02
J5
GND
J2
Layout Schematic
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M9999-022008-C
Micrel, Inc.
MIC2810
Top Layer
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M9999-022008-C
Micrel, Inc.
MIC2810
Bottom Layer
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M9999-022008-C
Micrel, Inc.
MIC2810
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.
February 2008
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M9999-022008-C