Micrel MIC68200-2.5YML 2a sequencing ldo with tracking and ramp control Datasheet

MIC68200
2A Sequencing LDO with Tracking
and Ramp Control™
General Description
Features
The MIC68200 is a high peak current LDO regulator
designed specifically for powering applications such
as FPGA core voltages that require high start up
current with lower nominal operating current. Capable
of sourcing 2A of current for start-up, the MIC68200
provides high power from a small MLF® leadless
package. The MIC68200 can also implement a variety
of power-up and power-down protocols such as
sequencing, tracking, and ratiometric tracking.
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The MIC68200 operates from a wide input range of
1.65V to 5.5V, which includes all of the main supply
voltages commonly available today. It is designed to
drive digital circuits requiring low voltage at high
currents (i.e. PLDs, DSP, microcontroller, etc.). The
MIC68200 incorporates a delay pin (DLY) for control
of power on reset output (POR) at turn-on and powerdown delay at turn-off. In addition there is a ramp
control pin (RC) for either tracking applications or
output voltage slew rate adjustment at turn-on. This is
important in applications where the load is highly
capacitive and in-rush currents can cause supply
voltages to fail and microprocessors or other complex
logic chips to hang up.
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Multiple MIC68200s can be daisy chained in two
modes. In tracking mode the output voltage of the
Master drives the RC pin of a Slave so that the Slave
tracks the main regulator during turn-on and turn-off.
In sequencing mode the POR of the Master drives the
enable (EN) of the Slave so that it turns on after the
Master and turns off before (or after) the Master. This
behavior is critical for power-up and power-down
control in multi-output power supplies. The MIC68200
is fully protected offering both thermal and current limit
protection and reverse current protection.
The MIC68200 has a junction temperature range of
–40°C to +125°C and is available in fixed as well as
an adjustable option. The MIC68200 is offered in the
tiny 10-pin 3mm x 3mm MLF® package.
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Stable with 4.7µF ceramic capacitor
Input voltage range: 1.65V to 5.5V
0.5V reference
+1.0% initial output tolerance
2A maximum output current – peak start up
1A Continuous Operating Current
Tracking on turn-on and turn-off with pin
strapping
Timing Controlled Sequencing On/Off
Programmable Ramp Control™ for in-rush
current limiting and slew rate control of the
output voltage on Turn-On and Turn-Off
Power-on Reset (POR) supervisor with
programmable delay time
Single Master can control multiple Slave
regulators with tracking output voltages
Tiny 3mm x 3mm MLF® package
Maximum dropout (VIN – VOUT) of 500mV over
temperature at 1A output current
Fixed and Adjustable Output Voltages
Excellent line and load regulation specifications
Logic controlled shutdown
Thermal shutdown and current limit protection
Applications
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FPGA/PLD Power Supply
Networking/Telecom Equipment
Microprocessor Core Voltage
High Efficiency Linear Post Regulator
Sequenced or Tracked Power Supply
Ramp Control is a trademark of Micrel, Inc.
MLF and MicroLeadFrame are 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
July 2006
M9999-071206
(408) 955-1690
Micrel, Inc.
MIC68200
Typical Application
MIC68200-1.8YML
VIN = 3.3V
EN
0.6nF
2x
47KΩ
10nF
IN
EN
RC
DLY
U1 OUT
SNS
Master
GND
4.7µF
µProcessor
I/O
POR
MIC68200-1.5YML
1nF
0.7nF
IN
EN
RC
DLY
U2
Slave
GND
OUT
SNS
4.7µF
CORE
/RESET
POR
U1.EN
U1.TDLY
U1.RC
U1.DLY
U1.TDLY
U1.TRC
U1 Fully Shut Down
U1.OUT
U2.EN= U1.POR
U2.RC
U2.TRC
U2.DLY
U2.TDLY
U2.TDLY
U2 Fully Shut Down
U2.OUT
U2.POR
Sequenced Dual Power Supply for I/O and Core Voltage of µProcessor
July 2006
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M9999-071206
(408) 955-1690
Micrel, Inc.
MIC68200
47KΩ
µProcessor
MIC68200-1.5YML
VIN = 1.8V
EN
10nF
IN
EN
RC
DELAY
U1
Master
OUT
GND
POR
I/O
4.7µF
MIC68200-1.2YML
10nF
IN
EN
RC
DELAY
U2
Slave
OUT
GND
POR
4.7µF
CORE
/RESET
U1 Fully Shut Down
U1.EN=U2.EN
U1.RC
U1.DLY
U2.RC=U1.OUT
U1.TRC
U2.TDLY
U2.TDLY
U2 Fully Shut Down
U2.DLY
U2.OUT
U1.POR=U2.POR
Tracking Dual Power Supply for I/O and Core Voltage of µProcessor
July 2006
3
M9999-071206
(408) 955-1690
Micrel, Inc.
MIC68200
Block Diagram
Ordering Information
Marking
Code
Output
Current
Voltage
Junction
Temp. Range
Package
MIC68200-1.2YML
ZC12
2.0A
1.2V
–40°C to +125°C
PB-Free 10-Pin 3x3 MLF®
MIC68200-1.5YML
ZC15
2.0A
1.5V
–40°C to +125°C
PB-Free 10-Pin 3x3 MLF®
MIC68200-1.8YML
ZC18
2.0A
1.8V
–40°C to +125°C
PB-Free 10-Pin 3x3 MLF®
MIC68200-2.5YML
ZC25
2.0A
2.5V
–40°C to +125°C
PB-Free 10-Pin 3x3 MLF®
MIC68200-3.3YML
ZC33
2.0A
3.3V
–40°C to +125°C
PB-Free 10-Pin 3x3 MLF®
MIC68200YML
ZAAA
2.0A
ADJ
–40°C to +125°C
PB-Free 10-Pin 3x3 MLF®
Part Number
Note:
For additional voltage options, contact Micrel Marketing.
July 2006
4
M9999-071206
(408) 955-1690
Micrel, Inc.
MIC68200
Pin Configuration
1
10
2
9
3
8
4
7
5
EP
6
10-Pin 3mm × 3mm MLF (ML)
MIC68200-x.xYML (Fixed)
MIC68200YML (Adjustable)
Pin Description (Pin Numbering may change depending on layout considerations)
3x3 MLF-10
Fixed
3x3 MLF-10
Adjustable
Pin Name
1,2
1,2
IN
3
3
DLY
Delay: Capacitor to ground sets internal delay timer. Timer delays
power-on reset (POR) output at turn-on and ramp down at turn-off.
4
4
RC
Ramp Control: Voltage driven for tracking applications. Capacitor to
ground sets slew rate during start-up.
5
5
EN
Enable (Input): CMOS compatible input. Logic high = enable and
logic low = shutdown.
6, EP
6, EP
GND
Ground: EP is connected to ground on 3x3 MLF-10L.
7
7
POR
8
8
SNS
Power-on Reset: Open-drain output device indicates when the
output is in regulation. High (open) means device is regulating within
10%. POR onset can be delayed using a single capacitor from Delay
to ground.
Adjustable regulators: Feedback input. Connect to external resistor
voltage divider.
Fixed regulators: Sense pin. Connect to output at load for point-ofload regulation.
9, 10
9,10
OUT
July 2006
Pin Function
Input: Input voltage supply pin. Place a capacitor to ground to
bypass the input supply
Output Voltage: Output of voltage regulator. Place capacitor to
ground to bypass the output voltage. Minimum load current is 100uA.
Nominal bypass capacitor is 4.7uf ceramic.
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Micrel, Inc.
MIC68200
Absolute Maximum Ratings(1)
Operating Ratings(2)
Supply Voltage (VIN) ................................................ 6V
Enable Input Voltage (VEN)..................... 0 to VIN + 0.3V
POR (VPOR)...................................................VIN + 0.3V
RC ...............................................................VIN + 0.3V
Power Dissipation...........................Internally Limited(3)
Junction Temperature ................ –40°C ≤ TJ ≤ +125°C
Storage Temperature (TS) .......... –65°C ≤ TJ ≤ +150°C
ESD Rating(4) ........................................................ 2KV
Supply voltage (VIN) .................................1.65V to 5.5V
Enable Input Voltage (VEN).............................. 0V to VIN
Ramp Control (VRC).......................................0V to 5.5V
Junction Temperature Range ......–40°C ≤ TJ ≤ +125°C
Package Thermal Resistance
3x3 MLF-10 (θJA) ...................................... 60°C/W
Electrical Characteristics(5)
TA = 25°C with VIN = VOUT + 1V; VEN = VIN; IOUT = 10mA; bold values indicate –40°C ≤ TJ ≤ +125°C, unless noted.
Parameter
Conditions
Min
Output Voltage Accuracy
10mA < IOUT < IL(max), VOUT + 1 ≤ VIN ≤ 5.5V
Typ
-2
Units
+2
%
Feedback Voltage
Adjustable version only
Feedback Current
Adjustable version only
10
Output Voltage Line Regulation
VIN = VOUT + 1V to 5.0V
0.06
0.5
V
Output Voltage Load Regulation
IL = 0mA to 2A
0.3
1
%
VIN – VO; Dropout Voltage
IL = 500mA
IL = 1.0A
IL = 2.0A
140
200
300
250
400
600
mV
mV
mV
Ground Pin Current
IL = 10mA
IL = 500mA
IL = 1.0A
IL = 2.0A
1.5
7
15
42
15
30
80
mA
mA
mA
mA
Shutdown Current
VEN = 0V; VOUT = 0V
0.01
10
µA
Current Limit
VOUT = 0V; VIN = 3.0V
3.4
6.0
A
Start-up Time
VEN = VIN; CRC = Open
25
150
µs
0.2
V
V
250
mV
0.49
2.0
0.50
Max
0.51
V
nA
Enable Input
Enable Input Threshold
Regulator enable
Regulator shutdown
1
Enable Hysteresis
Enable Input Current
50
100
0.8
2
VIL ≤ 0.2V (Regulator shutdown)
VIH ≤ 1V (Regulator enable)
µA
µA
POR Output
IPOR(LEAK)
VPOR = 5.5V; POR = High
VPOR(LO)
Output Logic-Low Voltage (undervoltage condition),
IPOR = 1mA
VPOR :
VOUT Ramping Up
VOUT Ramping Down
Threshold, % of VOUT below nominal
Delay Current
VDELAY = 0.75V
Delay Voltage (Note 6)
VPOR = High
July 2006
6
1
2
µA
µA
60
90
mV
7.5
10
12.5
%
10
12.5
15
%
0.7
1
1.3
µA
1.185
1.235
1.285
V
M9999-071206
(408) 955-1690
Micrel, Inc.
MIC68200
Parameter
Conditions
Min
Typ
Max
IRC
Ramp Control Current
IDISCHARGE(OUTPUT) (Note 7)
VOUT = 0.5VREF, VRAMP =0V
200mV < VRC < VTARGET ; Measure (VOUT – VRC)
Units
0.7
1
1.3
µA
25
45
70
mA
-50
25
100
mV
2
15
50
mV
Ramp Control
Tracking Accuracy:
(Note 8)
Tracking Accuracy:
(Note 8)
Fixed
Adjustable
Measure (VOUT - VRC x (VTARGET / 500mV))
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. Timer High Voltage along with Delay pin current (1µA nom) determines the delay per uF of capacitance. Typical delay is 1.1sec/µf
7. Discharge current is the current drawn from the output to ground to actively discharge the output capacitor during the shutdown process.
8. VTARGET is the output voltage of an adjustable with customer resistor divider installed between VOUT and Adj/Sns pin, or the rated output
voltage of a fixed device.
July 2006
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Micrel, Inc.
MIC68200
Typical Characteristics
45
Ground Current
vs. Output Current
2
Output Voltage
vs. Input Voltage
400
40
350
35
1.5
300
30
250
25
1
20
5
0
0.0
200
150
15
10
Dropout Voltage
vs. Output Current
VIN = VOUT + 1V
VOUT = 1.8V
COUT = 10µF
0.4
0.8
1.2
1.6
OUTPUT CURRENT (A)
2.0
0.5
0
0
2.00
VIN = VOUT + 1V
VOUT = 1.8V
COUT = 10µF
IOUT = 10mA
1
2
3
4
INPUT VOLTAGE (V)
5
100
VIN = VOUT + 1V
VOUT = 1.8V
COUT = 10µF
50
0
0.0
0.4
0.8
1.2
1.6
2.0
OUTPUT CURRENT (mA)
Output Voltage
vs. Temperature
1.95
1.90
1.85
1.80
1.75
1.70
1.65
1.60
1
Enable Threshold
vs. Input Voltage
0.9
0.8
0.6
VOUT = 1.8V
IOUT = 10mA
COUT = 10µF
0.4
1.9 2.4 2.9 3.4 3.9 4.4 4.9 5.4
INPUT VOLTAGE (V)
July 2006
20 40 60 80
TEMPERATURE (°C)
Current Limit
vs. Input Voltage
3.3
3.2
1
Output Noise
Spectral Density
0.1
3.6
3.5
3.4
0.7
0.5
4.0
3.9
3.8
3.7
VIN = VOUT + 1V
VOUT = 1.8V
COUT = 10µF
0.01
VIN = 2.8V
VOUT = 1.8V
COUT = 10µF
3.1
3.0
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
8
0.001
0.01 0.1
VIN = VOUT +1V
VOUT = 1.8V
COUT = 10µF
10 100 1,000 10,000
1
FREQUENCY (kHz)
M9999-071206
(408) 955-1690
Micrel, Inc.
MIC68200
Functional Characteristics
July 2006
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M9999-071206
(408) 955-1690
Micrel, Inc.
MIC68200
Applications Information
Enable Input
The MIC68200 features a TTL/CMOS compatible
positive logic enable input for on/off control of the
device. High (>1V) enables the regulator while low
(<.2V) disables the regulator. In shutdown the
regulator consumes very little current (only a few
microamperes of leakage). For simple applications the
enable (EN) can be connected to VIN (IN). While
MIC68200 only requires a few µA’s of enable current
to turn on, actual enable pin current will depend on the
overdrive (voltage exceeding 1V) in each particular
application.
Enable Connections for Logic Driven input
VIN = 3.3V
MIC68200-1.8BML
IN
OUT
RC
U1
Master
POR
EN
GND
DLY
4.7µF
10nF
Control Logic
High > 1V
MIC68200-1.5BML
IN
4.7µF
OUT
RC
U2
Slave
POR
EN
GND
DLY
1nF
Enable Connection for VIN-Driven and/or Slow
Risetime Inputs
Input Capacitor
An input capacitor of 0.1µF or greater is
recommended when the device is more than 4 inches
away from the bulk supply capacitance, or when the
supply is a battery. Small, surface mount chip
capacitors can be used for the bypassing. The
capacitor should be place within 1 inch of the device
for optimal performance. Larger values will help to
improve ripple rejection by bypassing the regulator
input, further improving the integrity of the output
voltage.
Output Capacitor
The MIC68200 requires an output capacitor for stable
operation. As a µCap LDO, the MIC68200 can
operate with ceramic output capacitors of 4.7µF or
greater with ESR’s ranging from a 3mΩ to over
300mΩ. Values of greater than 4.7µF improve
transient response and noise reduction at high
frequency.
X7R/X5R
dielectric-type
ceramic
capacitors are recommended because of their
superior
temperature
performance.
X7R-type
capacitors change capacitance by 15% over their
operating temperature range and are the most stable
type of ceramic capacitors. Larger output
capacitances can be achieved by placing tantalum or
aluminum electrolytics in parallel with the ceramic
capacitor. For example, a 100µF electrolytic in parallel
with a 4.7µF ceramic can provide the transient and
high frequency noise performance of a 100µF ceramic
at
a
significantly
lower
cost.
Specific
undershoot/overshoot performance will depend on
both the values and ESR/ESL of the capacitors.
VIN = 3.3V
~ 1V/mSec
MIC68200-1.8YML
IN
10KΩ
OUT
RC
U1
Master
POR
EN
GND
DLY
4.7µF
10nF
10nF
MIC68200-1.5YML
IN
OUT
RC
U2
Slave
POR
EN
GND
DLY
4.7µF
1nF
July 2006
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MIC68200
⎛C
TDLY = (1.1)⎜⎜ DLY
⎝ 1µA
Adjustable Regulator Design
OUT
*CFF
0.1µF
SNS
0.5V
COUT
4.7µF
*Required only for large
values of R1 and R2.
Adjustable Regulator with Resistors
The adjustable MIC68200 output voltage can be
programmed from 0.5V to 5.5V using a resistor divider
from output to the SNS pin. Resistors can be quite
large, up to 1MΩ because of the very high input
impedance and low bias current of the sense
amplifier. Typical sense input currents are less than
30nA which causes less than 0.3% error with R1 and
R2 less than or equal to 100KΩ. For large value
resistors (>50K) R1 should be bypassed by a small
capacitor (CFF = 0.1µF bypass capacitor) to avoid
instability due to phase lag at the ADJ/SNS input.
The output resistor divider values are calculated by:
⎛ R1
⎞
VOUT = 0.5V ⎜
+ 1⎟
⎠
⎝ R2
Power on Reset (POR) and Delay (DLY)
The power-on reset output (POR) is an open-drain
N-Channel device requiring a pull-up resistor to either
the input voltage or output voltage for proper voltage
levels. POR is driven by the internal timer so that the
release of POR at turn-on can be delayed for as much
as 1 second. POR is always pulled low when enable
(EN) is pulled low or the output goes out of regulation
by more than 10% due to loading conditions.
The internal timer is controlled by the DLY pin which
has a bidirectional current source and two limiting
comparators. A capacitor connected from DLY to
GND sets the delay time for two functions. On start
up, DLY sets the time from power good to the release
of the POR. At shut down, the delay sets the time
from disable (EN pin driven low) to actual ramp down
of the output voltage. The current source is +/-1µA,
which charges the capacitor from ~150mV (nominal
disabled DLY voltage) to ~1.25V. At turn on, the DLY
cap begins to charge when the output voltage reaches
90% of the target value. When the capacitor reaches
1.25V, the output of the POR is released to go high.
At turn off, the DLY cap begins to discharge when the
EN is driven low. When the cap reaches ~150mV the
output is ramped down. Both delays are nominally the
same, and are calculated by the same formula:
July 2006
Scale Factor is:
1.1 seconds/microfarad,
1.1 milliseconds/nanofarad, or
1.1 microseconds/picofarad.
R1
R2
⎞
⎟⎟
⎠
TDLYOFF is the time from lowering of EN to the start of
ramp down on the off cycle. TPOR is the time from
raising of EN to the release (low to high edge) of the
POR. This behavior means that a µP or other
complex logic system is guaranteed that power has
been good for a known time before the POR is
released, and they are further guaranteed that once
POR is pulled low, they have a known time to ‘tidy up’
memory or other registers for a well controlled
shutdown. In Master/Slave configurations the timers
can be used to assure that the Master is always
accurately regulating when the Slave is on.
Ramp Control
The ramp control (RC) has a bidirectional current
source and a sense amplifier, which together are used
to control the voltage at the output. When RC is below
the target voltage (nominal output voltage for fixed
voltage parts, 0.5V for adjustable parts) the RC pin
controls the output voltage. When RC is at or above
the target voltage, the output is controlled by the
internal regulator.
Tracking Applications: Driving RC from a Voltage
Source
Fixed Parts: If RC is driven from another (Master)
regulator the two outputs will track each other until the
Master exceeds the target voltage of the Slave
regulator. Typically the output of the MIC68200 will
track above the RC input by 30mV to 70mV. This
offset is designed to allow Master/Slave tracking of
same-voltage regulators. Without the offset, samevoltage Master/Slave configurations could suffer poor
regulation.
Adjustable Parts: The RC pin on adjustable versions
operates from 0V to 0.5V. To implement tracking on
an adjustable version, an external resistor divider
must be used. This divider is the nearly same ratio as
the voltage setting divider used to drive the Sense/Adj
pin. It is recommended that the ratio be adjusted to
track ~50mV (2% to 3%) above the target voltage if
the Master and Slave are operating at the same target
voltage.
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Micrel, Inc.
MIC68200
Sequencing Connections
Ramp Up: Cap Controlled Slew Rate
If a capacitor is connected to RC, the bidirectional
current source will charge the cap during startup and
discharge the cap during shutdown. The size of the
capacitor and the RC current (1µA nom) control the
slew rate of the output voltage during startup. For
example, to ramp up a 1.8V regulator from zero to full
output in 10mSec requires a 5.6nF capacitor.
10K
VIN = 2.5V
EN
MIC68200-1.8YML
IN
RC
EN
U1 OUT
Master POR
GND
I/O
4.7µF
DLY
µProcessor
CDlyM
For Fixed Versions:
Core
MIC68200-1.2YML
⎛C
TRC = VOUT ⎜⎜ RC
⎝ 1µA
⎞
⎟⎟
⎠
⎛ 1µA
SR ON = ⎜⎜
⎝ C RC
IN
⎞
⎟
⎟
⎠
Similarly, to slew an adjustable (any output voltage)
from 0 to full output in 10mSec requires a 20nF cap.
4.7µF
OUT
RC
U2
Slave
POR
EN
GND
DLY
CDlyS
/RESET
10K
For Adjustable Versions:
⎛C
TRC = 0.5 V ⎜⎜ RC
⎝ 1µA
⎞
⎟⎟
⎠
⎛ 1µA
SR ON = 2VOUT ⎜⎜
⎝ C RC
⎞
⎟
⎟
⎠
Delayed Sequencing
CDlyS > CDlyM [CDlyS=2nF; CDlyM=1nF]
Ramp Down: Turn Off Slew Rate
When EN is lowered and the DLY pin has discharged,
the RC pin and the OUT pin slew toward zero. For
fixed voltage devices, the RC pin slew rate is 2 to 3
times the SRON defined above. For adjustable voltage
devices the RC pin slew is much higher. In both
cases, turn off slew rate may be determined by the
RC pin for low values of output capacitor, or by the
maximum discharge current available at the output for
large values of output capacitor. Turn off slew rate is
not a specified characteristic of the MIC68200.
Sequencing Configurations
Sequencing refers to timing based Master/Slave
control between regulators. It allows a Master device
to control the start and stop timing of a single or
multiple Slave devices. In typical sequencing the
Master POR drives the Slave EN. The sequence
begins with the Master EN driven high. The Master
output ramps up and triggers the Master DLY when
the Master output reaches 90%. The Master DLY then
determines when the POR is released to enable the
Slave device. When the Master EN is driven low, the
Master POR is immediately pulled low causing the
Slave to ramp down. However, the Master output will
not ramp down until the Master DLY has fully
discharged. In this way, the Master power can remain
good after the Slave has been ramped down.
Windowed Sequencing
CDlyS < CDlyM [CDlyS=1nF; CDlyM=2nF]
In sequencing configurations the Master DLY controls
the turn-on time of the Slave and the Slave DLY
controls the turn-off time of the Slave.
July 2006
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Micrel, Inc.
MIC68200
Normal Tracking
In normal tracking the Slave RC pin is driven from the
Master output. The internal control buffering assures
that the output of the Slave is always slightly above
the Master to guarantee that the Slave properly
regulates (based on its own internal reference) if
Master and Slave are both fixed voltage devices of the
same output voltage. The schematic and plot below
show a 1.2 volt device tracking a 1.8 volt device
through the entire turn-on / turn-off sequence. Note
that since the RC pin will overdrive the target voltage
(to assure proper regulation) the ramp down delay is
longer than the POR delay during turn-on.
Fixed voltage versions of MIC68200 have two internal
voltage dividers: one for setting the output voltage and
the other for driving the tracking circuitry. Adjustable
parts have up to two external dividers: one from
output to SNS (to set the output voltage) and one from
the output to the Slave RC pin (in tracking
configurations). Also, the RC pin in fixed parts
operates at the same voltage as the output, whereas
the RC pin in adjustable parts operates at the 0.5V
reference. To setup a normal tracking configuration,
the divider driving the Slave RC pin is the same ratio
(or nearly the same – if both Master and Slave are set
to the same output voltage, the Slave RC divider
should be adjusted 2% to 4% higher) as the divider
driving the Slave SNS pin. This is shown below.
Fixed Voltage Devices
Adjustable Voltage devices
Tracking Configurations
10K
VIN = 2.5V
EN
10K
MIC68200-1.8YML
1nF
1nF
IN
EN
RC
DLY
U1
Master
OUT
SNS
GND
POR
MIC68200YML
VIN = 3.3V
VOUT1
4.7µF
EN
2nF
1nF
MIC68200-1.2YML
NC
IN
EN
RC
DLY
U2
Slave
GND
OUT
SNS
POR
IN
EN
RC
DLY
U1
Master
GND
OUT
SNS
POR
VOUT1
10.0K
1.0K
2.50K
383Ω
4.7µF
MIC68200YML
VOUT2
4.7µF
POR
NC
IN
EN
RC
DLY
U2
Slave
OUT
SNS
GND
POR
VOUT2
10.0K
4.7µF
3.83K
POR
July 2006
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Micrel, Inc.
MIC68200
Ratiometric Tracking
Ratiometric tracking allows independent ramping
speeds for both regulators so that the regulation
voltage is reached at the same time. This is
accomplished by adding a resistor divider between the
Master output pin and the Slave RC pin. The divider
should be scaled such that the Slave RC pin reaches
or exceeds the target output voltage of the Slave as
the Master reaches its target voltage.
Ratiometric tracking may be used with adjustable
parts by simply connecting the RC pins of the Master
and Slave. Use a single RC capacitor of twice the
normal value (since twice the current is injected into
the single RC cap).
Alternatively, adjustable parts
may use ratiometric tracking in a manner similar to
standard tracking, with the tracking divider changed to
the same resistor ratio driving the Master Adj/Sns pin.
Fixed Voltage Devices
Adjustable Voltage Devices
10K
VIN = 2.5V
EN
10KΩ
MIC68200-1.8YML
1nF
1nF
IN
EN
RC
DLY
U1
Master
GND
OUT
SNS
POR
VOUT1
1K
MIC68200YML
VIN = 3.3V
4.7µF
EN
1.5K
3nF
1nF
MIC68200-1.2YML
NC
IN
EN
RC
DLY
U2
Slave
OUT
SNS
GND
POR
IN
EN
RC
DLY
U1
Master
GND
OUT
SNS
POR
VOUT1
10.0K
MIC68200YML
VOUT2
4.7µF
POR
NC
IN
EN
RC
DLY
U2
Slave
OUT
SNS
GND
POR
4.7µF
2.5K
VOUT2
10.0K
4.7µF
3.83K
POR
Final Note on Tracking
The MIC68200 does not fully shutdown until the output load is discharged to near zero. If RC is driven from an external source in
a tracking configuration, and the external source does not go to zero on shutdown it may prevent complete shutdown of the
MIC68200. This will cause no damage, but some Q current will remain and may cause concern in battery operated portable
equipment. Also, when RC is driven in tracking mode, pulling EN low will not cause the output to drop. Maintaining low EN in
tracking mode simply means that the MIC68200 will shutdown when the tracking voltage gets near zero. In no case can the
MIC68200 enter the tracking mode unless EN is pulled high.
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M9999-071206
(408) 955-1690
Micrel, Inc.
MIC68200
Package Information
10-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.
© 2005 Micrel, Inc.
July 2006
15
M9999-071206
(408) 955-1690