MIC MIC3808BM Push-pull pwm controller Datasheet

MIC3808/3809
Micrel
MIC3808/3809
Push-Pull PWM Controller
General Description
Features
The MIC3808 and MIC3809 are a family of complementary
output push-pull PWM control ICs that feature high speed and
low power consumption. The MIC3808/9 are ideal for telecom
level (36V to 75V) isolated step down dc/dc conversion
applications where high output current, small size, and high
efficiency are required.
The dual-ended push-pull architecture of the MIC3808/9
allows more efficient utilization of the transformer than singleended topologies, allowing smaller size dc/dc solutions.
Additionally, the out-of-phase push-pull topology allows a
higher effective duty cycle, reducing input and output ripple
as well as stress on the external components. The dead-time
between the two outputs is adjustable between 60ns to
200ns, limiting the duty cycle of each output stage to less than
50%.
The MIC3808/9 are built on a low-power, high-speed BiCMOS
process. The 130µA start-up current and 1mA run-current
reduce the size of the start-up circuitry and allow high
efficiency even at light loads. The high-speed internal 4MHz
error amplifier allows MIC3808/9 operation up to 1MHz.
The MIC3808 has a turn-on threshold of 12.5V whereas the
MIC3809 has a lower turn-on threshold of 4.3V. Both devices
are available in SOP-8 and MSOP-8 package options with an
operating range of –40°C to +85°C.
Data sheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
•
•
•
•
•
•
•
Dual output drive stages in push-pull configuration
Leading edge current-sense blanking
130µA typical start-up current
1mA typical run current
Operation to 1MHz
Internal soft start
On-chip error amplifier with 4MHz gain bandwidth
product
• On-chip VDD clamping
• Output drive stages capable of 500mA peak source
current, 1A peak sink current
Applications
• High efficiency “brick” power supply modules
• Half bridge converters
• Full bridge converters
• Push-pull converters
• Voltage-fed push-pull converters
• Telecom equipment and power supplies
• Networking power supplies
• Industrial power supplies
• 42V automotive power supplies
• Base stations
Typical Application
VOUT
12V 100W
VIN
36V to 75V
Start-Up
Circuitry
MIC3808
RC
VDD
GND OUTA
COMP OUTB
FB
CS
Slope
Comp
Reference
& Isolation
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
April 2005
1
MIC3808/3809
MIC3808/3809
Micrel
Ordering Information
Part Number
Standard
MIC3808BM
MIC3809BM
Lead-Free
Turn On
Threshold
Turn Off
Threshold
Temperature Range
Package
MIC3808YM
12.5V
8.3V
–40°C to +85°C
8-Pin SOIC
MIC3809YM
4.3V
4.1V
–40°C to +85°C
8-Pin SOIC
MIC3808BMM
MIC3808YMM
12.5V
8.3V
–40°C to +85°C
8-Pin MSOP
MIC3809BMM
MIC3809YMM
4.3V
4.1V
–40°C to +85°C
8-Pin MSOP
Pin Configuration
COMP 1
8 VDD
FB 2
7 OUTA
CS 3
6 OUTB
RC 4
5 GND
SOIC-8 (M)
MSOP-8 (MM)
Pin Description
Pin Number
Pin Name
Pin Function
1
COMP
COMP is the output of the error amplifier and the input of the PWM comparator. The error amplifier in the MIC3808 is a true low-output impedance,
4MHz operational amplifier. As such, the COMP pin can both source and
sink current. However, the error amplifier is internally current limited, so that
zero duty cycle can be externally forced by pulling COMP to GND. The
MIC3808 family features built-in full cycle soft start. Soft start is implemented as a clamp on the maximum COMP voltage.
2
FB
The inverting input to the error amplifier. For best stability, keep FB lead
length as short as possible and FB stray capacitance as small as possible.
3
CS
The input to the PWM, peak current, and overcurrent comparators. The
overcurrent comparator is only intended for fault sensing. Exceeding the
overcurrent threshold will cause a soft start cycle. An internal MOSFET
discharges the current sense filter capacitor to improve dynamic performance of the power converter.
4
RC
The oscillator programming pin. The MIC3808’s oscillator tracks VDD and
GND internally, so that variations in power supply rails minimally affect
frequency stability. Only two components are required to program the
oscillator, a resistor (tied to the VDD and RC), and a capacitor (tied to the RC
and GND). The approximate oscillator frequency is determined by the simple
FOSCILLATOR =
formula:
1.41
RC
where frequency is in Hertz, resistance in Ohms, and capacitance in Farads.
The recommended range of timing resistors is between 7kΩ and 200kΩ and
range of timing capacitors is between 100pF and 1000pF. Timing resistors
less than 7kΩ should be avoided. For best performance, keep the timing
capacitor lead to GND as short as possible, the timing resistor lead from VDD
as short as possible, and the leads between timing components and RC as
short as possible. Separate ground and VDD traces to the external timing
network are encouraged.
MIC3808/3809
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April 2005
MIC3808/3809
Micrel
Pin Description
Pin Number
Pin Name
5
GND
Ground
6
OUTB
7
OUTA
Alternating high current output stages. Both stages are capable of driving the
gate of a power MOSFET. Each stage is capable of 500mA peak source
current, and 1A peak sink current. The output stages switch at half the
oscillator frequency, in a push/pull configuration. When the voltage on the
RC pin is rising, one of the two outputs is high, but during fall time, both
outputs are off. This “dead time” between the two outputs, along with a
slower output rise time than fall time, insures that the two outputs can not be
on at the same time. This dead time is typically 60ns to 200ns and depends
upon the values of the timing capacitor and resistor. The high-current output
drivers consist of MOSFET output devices, which switch from VDD to GND.
Each output stage also provides a very low impedance to overshoot and
undershoot. This means that in many cases, external Schottky clamp diodes
are not required.
8
VDD
April 2005
Pin Function
The power input connection for this device. Although quiescent VDD current
is very low, total supply current will be higher, depending on OUTA and
OUTB current, and the programmed oscillator frequency. Total VDD current
is the sum of quiescent VDD current and the average OUT current. Knowing
the operating frequency and the MOSFET gate charge (Qg), average OUT
current can be calculated from IOUT = Qg × F, where F is frequency. To
prevent noise problems, bypass VDD to GND with a ceramic capacitor as
close to the chip as possible. A 1µF decoupling capacitor is recommended.
3
MIC3808/3809
MIC3808/3809
Micrel
Absolute Maximum Ratings (Note 1)
Operating Ratings (Note 2)
Supply Voltage (IDD ≤ 10mA) ...................................... +15V
Supply Current ........................................................... 20mA
OUTA/OUTB Source Current (peak) .......................... –0.5A
OUTA/OUTB Sink Current (peak) ................................ 1.0A
Comp Pin ......................................................................VDD
Analog Inputs (FB, CS) ........................ –0.3V to VDD +0.3V
NOT TO EXCEED 6V
Junction Temperature .............................. –55°C to +150°C
Storage Temperature ............................... –65°C to +150°C
Lead Temperature (soldering, 10 sec.) ................... +300°C
ESD Rating, Note 3 ...................................................... 2kV
VDD Input Voltage (VDD) ........................................ Note 11
Oscillator Frequency (fOSC) ....................... 10kHz to 1MHz
Ambient Temperature (TA) ......................... –40°C to +85°C
Package Thermal Resistance
SOIC-8 (θJA) ...................................................... 160°C/W
MSOP-8 (θJA) .................................................... 206°C/W
Electrical Characteristics
TA = TJ = –40°C to +85°C, VDD = 10V (Note 9), 1µF capacitor from VDD to GND, R = 22KΩ, C = 330pF.
Parameter
Condition
Min
Typ
Max
Units
180
200
220
kHz
Note 4
0.44
0.5
0.56
V/V
COMP = 2V
1.95
2
2.05
V
1
µA
Oscillator Section
Oscillator Frequency
Oscillator Amplitude/VDD
Error Amp Section
Input Voltage
Input Bias Current
–1
Open Loop Voltage Gain
(Guaranteed by design)
60
80
dB
COMP Sink Current
FB = 2.2V, COMP = 1V
0.3
2.5
mA
COMP Source Current
FB = 1.3V, COMP = 3V, Note 5
–0.15
–0.5
mA
COMP Clamp Voltage
VFB = 0V
3.1
3.6
4.0
V
Maximum Duty Cycle
Measured at OUTA or OUTB
48
49
50
%
Minimum Duty Cycle
COMP = 0V
0
%
PWM Section
Current Sense Section
Gain
Note 6 (Guaranteed by design)
1.9
2.2
2.5
V/V
Maximum Input Signal
Note 7
0.45
0.5
0.55
V
CS to Output Delay
COMP = 3V, CS from 0 to 600mV
70
200
ns
CS Source Current
CS Sink Current
–200
CS = 0.5V, RC = 5.5V, Note 8
Over Current Threshold
COMP to CS Offset
CS = 0V
nA
5
10
mA
0.7
0.75
0.8
V
0.35
0.8
1.2
V
Output Section
OUT Low Level
I = 100mA
0.5
1
V
OUT High Level
I = –50mA, VDD - OUT
0.5
1
V
Rise Time
CL = 1nF
25
60
ns
Fall Time
CL = 1nF
25
60
ns
MIC3808/3809
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April 2005
MIC3808/3809
Micrel
Parameter
Condition
Min
Typ
Max
Units
Start Threshold
MIC3808, Note 9
MIC3809
11.5
4.1
12.5
4.3
13.5
4.5
V
V
Minimum Operating Voltage
After Start
MIC3808
MIC3809
7.6
3.9
8.3
4.1
9
4.3
V
V
Hysteresis
MIC3808
MIC3809
3.5
0.1
4.2
0.2
5.1
0.3
V
V
FB = 1.8V, Rise from 0.5V to 3V
2.5
20
ms
Startup Current
VDD < Start Threshold
130
260
µA
Operating Supply Current
FB = 0V, CS = 0V, Notes 9 and 10
1
2
mA
VDD Zener Shunt Voltage
IDD = 10mA, Note 12
14
15
V
Undervoltage Lockout Section
Soft Start Section
COMP Rise Time
Overall Section
13
Note 1.
Exceeding the absolute maximum rating may damage the device.
Note 2.
The device is not guaranteed to function outside its operating rating.
Note 3.
Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.
Note 4.
Measured at RC. Signal amplitude tracks VDD.
Note 5.
The COMP pin is internally clamped to 3.65V(typ). The COMP pin source current is tested at VCOMP = 3.0V to avoid interfering with this clamp
voltage. The minimum source current increases as VCOMP approaches VCLAMP.
Note 6.
Gain is defined by A =
Note 7.
Parameter measured at trip point of latch with FB at 0V.
Note 8.
The internal current sink on the CS pin is designed to discharge an external filter capacitor. It is not intended to be a DC sink path.
Note 9.
For MIC3808, set VDD above the start threshold before setting at 10V.
∆VCOMP
∆VCS
, 0 ≤ VCS ≤ 0.4V.
Note 10. Does not include current in the external oscillator network.
Note 11. Maximum operating voltage is equal to the VDD [zener] shunt voltage. When operating at or near the shunt voltage, care must be taken to limit
the VDD pin current to less than the 20mA VDD maximum supply current rating.
Note 12. Start threshold and Zener Shunt threshold track one another.
April 2005
5
MIC3808/3809
MIC3808/3809
Micrel
Typical Characteristics
MIC3808 VDD
vs. IDD
4.0
7
3.5
OSCILLATOR (%)
5
2.5
2.0
1.5
4
3
1.0
2
0.5
1
5
10
0
0
15
2
4
6
VDD (V)
MIC3809 Oscillator
Frequency Variation
vs. Temperature
Frequency
vs. RC Values
C = 100pF
VDD = 5V
FREQUENCY (kHz)
VDD = 10V
-1
4
6
8 10
VDD (V)
12
14
RC Pin Capacitance
vs. Deadtime
200
C = 220pF
C = 270pF
C = 330pF
C = 470pF
C = 680pF
100k
2
175
-2
150
125
100
900
1000
700
800
600
50
200k
500
50k
100k
150k
RESISTANCE (kΩ)
300
400
10k
0
0
-3
-40 -20 0 20 40 60 80 100120140
TEMPERATURE (°C)
200
75
C = 1000pF
100
FREQUENCY (%)
1
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
-0.4
0
VDD = 10V
1M
2
0
8 10 12 14 16
VDD (V)
DEAD TIME (ns)
0
0
3
MIC3809 Oscillator Variation
vs. VDD
6
3.0
IDD (mA)
IDD CURRENT (mA)
MIC3809 VDD
vs. IDD
CAPACITANCE (pF)
RC Pin Resistance
vs. Deadtime
2.05
VREFERENCE (V)
DEADTIME (ns)
88
87
86
85
2.010
2.01
2.005
1.99
1.97
1.95
1.93
1.91
200
180
160
140
120
80
100
60
40
0
20
1.85
4
6
8
10 12 14
VDD (V)
RESISTANCE (kΩ)
MIC3808 Current Limit
Threshold vs. VDD
1.995
1.990
1.985
1.975
1.87
83
2.000
1.980
1.89
84
16
18
1.970
8
MIC3809 Current Limit
Threshold vs. VDD
0.505
10 11 12 13 14 15 16
VDD (V)
2.02
2.02
0.503
0.497
0.495
0.493
2.01
VREFERENCE (V)
VTHRESHOLD (V)
0.499
VTHRESHOLD (V)
9
Error Amplifier Reference
Voltage vs. Temperature
0.501
0.501
0.499
0.497
2.01
2.00
2.00
1.99
1.99
1.98
0.495
0.491
0.489
8
REFERENCE
vs. VDD
2.015
2.03
VREFERENCE (V)
89
MIC3808 V
MIC3809 VREFERENCE
vs. VDD
1.98
9
MIC3808/3809
10 11 12 13 14 15 16
VDD (V)
0.493
4
6
8
10 12
VDD (V)
6
14
16
1.97
-40 -20 0 20 40 60 80 100120140
TEMPERATURE (°C)
April 2005
MIC3808/3809
Micrel
Error Ampifier
3
IDD (mA)
1
VDD = 10V
0
-1
-2
-3
-40 -20 0 20 40 60 80 100120140
TEMPERATURE (°C)
April 2005
MAGNITUDE (dB)
2
120
180
100
160
80
140
120
60
Magnitude
40
80
20
0
100
60
PHASE (°)
VDD Supply Current
vs. Temperature
40
Phase
-20
20
-40
1
0
10 100 1k 10k 100K 1M 10M
FREQUENCY (Hz)
7
MIC3808/3809
MIC3808/3809
Micrel
Functional Diagram
COMP
1
FB
2
CS
3
8
3.65V
Overcurrent
Comparator
Peak Current
Comparator
VDD
14V
0.75V
2.0V
2.2V
0.5V
Error
Amplifier
7
VDD OK
OUTA
Oscillator
S
0.8V
Q
PWM
Latch
PWM
Comparator
R
1.2R
Q
S
VDD —1V
S1
S2
Q
Q
R
T
/Q
R
VDD
0.5V
R
6
Soft Start
Voltage
Reference
OUTB
Slope = 1V/ms
5
GND
4
RC
Figure 1. MIC3808 Block Diagram
error amplifier at the COMP pin. As the softstart voltage rises,
it allows the COMP pin voltage to rise, which in turn allows the
duty cycle of the output drivers to increase. The internal
softstart voltage is discharged and remains discharged during the following conditions:
1. The VDD voltage drops below the turn-off
threshold
2. The voltage on the CS pin exceeds the
overcurrent comparator threshold
Once the internal softstart discharge FET is turned on, it
cannot be turned off until the internal softstart voltage drops
down below 0.5V. This insures a clean restart.
Oscillator
The oscillator operates at twice the switching frequency of
either OUTA or OUTB. The oscillator generates a sawtooth
waveform on the RC pin. The rising edge of the waveform is
controlled by the external resistor/capacitor combination.
The fall time is set by the on-resistance of the discharge FET
(see Figure 2). The fall time sets the delay (dead time)
between the turn-off of one output driver and the turn-on of the
other driver. A toggle flip-flop insures that drive signals to
OUTA and OUTB are alternated and therefore insures a
maximum duty cycle of less than 50% for each output driver.
Graphs of component values vs. oscillator frequency and
dead time are shown in the typical characteristic section of
this specification.
Functional Description
The MIC3808/9 is a high-speed power supply controller with
push-pull output drive capability. MIC3808 has a higher VDD
turn-on threshold and more hysteresis between VDD turn-on
and turn-off than the MIC3809. The outputs of the controller
operate in a push-pull fashion with a guaranteed dead time
between them. A block diagram of the MIC3808/9 controller
is shown in Figure 1.
VDD and Turn-on Sequence
The oscillator and output gate drive signals are disabled
when VDD is lower than the turn on threshold. Circuitry in the
output drivers eliminates glitching or random pulsing during
the start-up sequence. The oscillator is enabled when VDD is
applied and reaches the turn-on threshold. The VDD comparator also turns off the internal soft-start discharge FET,
slowly bringing up the COMP pin voltage.
The VDD pin is internally clamped. As VDD approaches this
clamp voltage, the VDD current will increase over the normal
current draw of the IC. Exceeding the VDD zener shunt
voltage may cause excessive power dissipation in the
MIC3808/9.
Soft-Start
The soft start feature helps reduce surge currents at the
power supply input source. An internal current source and
capacitor ramp up from 0V to near Vdd at a typical rate of
1V/ms. The softstart feature limits the output voltage of the
MIC3808/3809
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April 2005
MIC3808/3809
Micrel
A pulse-by-pulse current limit occurs when the inductor
current signal at the CS pin exceeds the peak current limit
threshold. The on-time is terminated for the remainder of the
switching cycle, regardless of whether OUTA or OUTB is
active.
If the signal at the CS pin goes past the peak threshold and
exceeds the overcurrent limit threshold, the overcurrent limit
comparator forces the soft start node to discharge and
initiates a soft start reset.
An internal FET discharges the CS pin at the end of the
oscillator charge time. The FET turns on when the voltage on
the RC pin reaches the upper threshold (VDD/2) and remains
on for the duration of the RC pin discharge time and for
typically 100ns after the start of the next on-time period. The
100ns period at the beginning of the on-time implements a
front edge blanking feature that prevents false triggering of
the PWM comparator due to noise spikes on the leading edge
of the current turn-on signal. The front edge blanking also
sets the minimum on-time for OUTA and OUTB. The timing
diagram for the CS pin is shown in Figure 3.
VDD
4
RC
VDD
2
S
Q
R
OSCILLATOR
OUTPUT
0.2V
Figure 2. Oscillator
The voltage source to the resistor/capacitor timing components is VDD. The internal turn-off comparator threshold in the
oscillator circuit is VDD/2. This allows the oscillator to track
changes in VDD and minimize frequency variations in the
oscillator. The oscillator frequency can be roughly approximated using the following formula:
F_oscillator = 1.41/R*C
Where: frequency is in Hz
Resistance is in Ohms
Capacitance is in Farads.
Graphs of oscillator frequency and dead time vs component
values are shown in the Typical Characteristic section of this
specification. The recommended range of timing resistors
and capacitors is 10kΩ to 200kΩ and 100pF to 1000pF. To
minimize oscillator noise and insure a stable waveform the
following layout rules should be followed:
1. The higher impedance of capacitor values less
than 100pF may causes the oscillator circuit to
become more susceptible to noise. Parasitic pin
and etch trace capacitances become a larger
part of the total RC capacitance and may
influence the desired switching frequency.
2. The circuit board etch between the timing
resistor, capacitor, RC pin and ground must be
kept as short as possible to minimize noise
pickup and insure a stable oscillator waveform.
3. The ground lead of the capacitor must be routed
close to the ground lead of the MIC3808/9.
Current Sensing and Overcurrent Protection
The CS pin features are:
1. Peak current limit
2. Overcurrent limit
3. Internal current sense discharge
4. Front edge blanking
In current mode control, a PWM comparator uses the inductor
current signal and the error amplifier signal to determine the
operating duty cycle. In the MIC3808/9 the signal at the CS
pin is level shifted up before it reaches the PWM comparator
as shown in Figure 1. This allows operation of the error
amplifier and PWM comparator in a linear region.
There are two current limit thresholds in the MIC3808/9; peak
current limit and overcurrent limit. The normal operating
voltage at the CS pin is designed less than these thresholds.
April 2005
Max ON time
dead time
RC Pin
Oscillator
Reset
dead time
Front edge blanking
CS Pin
Minimum ON time
OUTA
OUTB
Figure 3. Timing Diagram
Error Amplifier
The error amplifier is part of the voltage control loop of the
power supply. The FB pin is the inverting input to the error
amplifier. The non-inverting input is internally connected to a
reference voltage. The output of the error amplifier, COMP,
is connected to the PWM comparator. A voltage divider
between the error amplifier output (COMP pin) and the PWM
comparator allows the error amplifier to operate in a linear
region for better transient response. The output of the error
amplifier (COMP pin) is limited to typically 3.65V to prevent
the COMP pin from rising up too high during startup or during
a transient condition. This feature improves the transient
response of the power supply.
9
MIC3808/3809
MIC3808/3809
Micrel
Output Drivers
OUTA and OUTB are alternating output stages, which switch
at half the oscillator frequency. A toggle flip-flop in the
MIC3808/9 guarantee both outputs will not be on at the same
time. The RC discharge time is the dead time, where both
outputs are off. This provides an adjustable non-overlap time
to prevent shoot through currents and transformer saturation
in the power supply.
The output drivers are inhibited when VDD is below the
undervoltage threshold. Internal circuitry prevents the output
drivers from glitching high when VDD is first applied to the
MIC3808/9 controller.
Decoupling and PCB Layout
PCB layout is critical to achieve reliable, stable and efficient
operation. A ground plane is required to control EMI and
minimize the inductance in power, signal and return paths.
The following guidelines should be followed to insure proper
operation of the circuit:
• Low level signal and power grounds should be kept
separate and connected at only one location, preferably
the ground pin of the control IC. The ground signals for
the current sense, voltage feedback and oscillator
MIC3808/3809
should be grouped together. The return signals for the
gate drives should be grouped together and a common
connection made at the ground pin of the controller. The
low level signals and their returns must be kept separate
from the high current and high voltage power section of
the power supply.
• Avoid running sensitive traces, such as the current
sense and voltage feedback signals next to or under
power components, such as the switching FETs and
transformer.
• If a current sense resistor is used, it’s ground end must
be located very close to the ground pin of the MIC3808/
9 controller. Careful PCB layout is necessary to keep
the high current levels in the current sense resistor from
running over the low level signals in the controller.
• A minimum 1µf bypass capacitor must be connected
directly between the VDD and GND pins of the MIC3808/
9. An additional 0.1uf capacitor between the VDD end
oscillator frequency setting resistor and the ground end
of the oscillator capacitor may be necessary if the
resistor is a distance away from the main 1µF bypass
capacitor
10
April 2005
MIC3808/3809
Micrel
Package Information
0.026 (0.65)
MAX)
PIN 1
0.157 (3.99)
0.150 (3.81)
DIMENSIONS:
INCHES (MM)
0.020 (0.51)
0.013 (0.33)
0.050 (1.27)
TYP
0.064 (1.63)
0.045 (1.14)
45°
0.0098 (0.249)
0.0040 (0.102)
0°–8°
0.197 (5.0)
0.189 (4.8)
0.010 (0.25)
0.007 (0.18)
0.050 (1.27)
0.016 (0.40)
SEATING
PLANE
0.244 (6.20)
0.228 (5.79)
8-Pin SOIC (M)
0.199 (5.05)
0.187 (4.74)
0.122 (3.10)
0.112 (2.84)
DIMENSIONS:
INCH (MM)
0.120 (3.05)
0.116 (2.95)
0.036 (0.90)
0.032 (0.81)
0.043 (1.09)
0.038 (0.97)
0.012 (0.30) R
0.008 (0.20)
0.004 (0.10)
0.012 (0.3)
0.0256 (0.65) TYP
5° MAX
0° MIN
0.007 (0.18)
0.005 (0.13)
0.012 (0.03) R
0.039 (0.99)
0.035 (0.89)
0.021 (0.53)
8-Pin MSOP (MM)
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The information furnished by Micrel in this datasheet 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
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© 2005 Micrel, Incorporated.
April 2005
11
MIC3808/3809
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