Micrel MIC5249-1.8YMM 300ma î¼cap ldo with programmable power-on reset delay Datasheet

MIC5249
300mA µCap LDO with
Programmable Power-On Reset Delay
General Description
Features
The MIC5249 is an efficient, precise 300mA CMOS
voltage regulator with power on reset (POR) delay which
can be implemented via an external capacitor. It offers 1%
initial accuracy, extremely low dropout voltage (typically
400mV @ 300mA), and low ground current (typically
85mA) over load.
Designed specifically for noise-critical applications in handheld or battery-powered devices, the MIC5249 comes
equipped with a noise reduction feature to filter the output
noise via an external capacitor. Other features of the
MIC5249 include a logic-compatible enable pin, current
limit, thermal shutdown, ultra-fast transient response, and
an active clamp to speed up device turnoff.
The MIC5249 also works with low-ESR ceramic
capacitors, reducing the amount of board space necessary
for power applications, critical in hand-held wireless
devices.
The MIC5249 is available in the MSOP-8 package.
Data sheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
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300mA output current
High PSRR: 65dB@120Hz
Stable with ceramic output capacitor
Power-on-Reset (POR) output with adjustable delay
time
High output accuracy:
− ±1.0% initial accuracy
− ±3.0% over temperature
Low dropout voltage of 340mV @ 300mA
Low quiescent current: 85µA
Zero current shutdown mode
Thermal-shutdown and current-limit protection
Tiny MSOP-8 package
Applications
• Cellular phones
• PDAs
• Fiber optic modules
Typical Application
Ultra-Low Noise Application
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
March 2012
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M9999-030812
Micrel, Inc.
MIC5249
Ordering Information
Voltage(1)
Junction Temperature Range
Package
MIC5249-1.5YMM
1.5V
–40°C to +125°C
8-Pin MSOP
MIC5249-1.8YMM
1.8V
–40°C to +125°C
8-Pin MSOP
MIC5249-2.5YMM
2.5V
–40°C to +125°C
8-Pin MSOP
MIC5249-2.6YMM
2.6V
–40°C to +125°C
8-Pin MSOP
MIC5249-2.8YMM
2.8V
–40°C to +125°C
8-Pin MSOP
MIC5249-2.85YMM
2.85V
–40°C to +125°C
8-Pin MSOP
MIC5249-3.0YMM
3.0V
–40°C to +125°C
8-Pin MSOP
MIC5249-3.3YMM
3.3V
–40°C to +125°C
8-Pin MSOP
Part Number
Note:
1. Other voltages available. Contact Micrel Marketing for details.
Pin Configuration
CBYP 1
8 ENABLE
DELAY 2
7 RESET
GND 3
6 NC
VIN 4
5 VOUT
8-pin MSOP (MM)
Pin Description
Pin Number
Pin Name
1
CBYP
Reference Bypass. Connect external 0.01µF capacitor to GND to reduce output noise. May be left
open.
2
DELAY
Delay Set Input. Connect external capacitor to GND to set the delay of the Error Flag.
3
GND
Ground.
4
VIN
Supply Input.
5
VOUT
6
NC
7
RESET
8
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ENABLE
Pin Function
Regulator Output.
No Connect.
RESET Output. Open-drain output. Active low indicates an output undervoltage condition.
Enable Input: CMOS-compatible input. Logic high = enable; Logic low = shutdown. Do not leave
open.
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Micrel, Inc.
MIC5249
Absolute Maximum Ratings(1)
Operating Ratings(2)
Supply Voltage (VIN) ............................................. 0V to +7V
Enable Voltage (VEN)............................................ 0V to +7V
Power Dissipation (PD). .......................... Internally Limited(3)
Junction Temperature (TJ) ........................–40°C to +125°C
Lead Temperature (soldering, 5sec.)......................... 260°C
Storage Temperature (Ts) .........................–65°C to +150°C
ESD Rating(4) ................................................. ESD Sensitive
Supply voltage (VIN) ........................................ +2.7V to +6V
Enable Voltage (VEN).............................................. 0V to VIN
Junction Temperature (TJ) ........................ –40°C to +125°C
Package Thermal Resistance
MSOP (θJA)......................................................160°C/W
Electrical Characteristics
VIN = VOUT + 1V; COUT = 2.2µF, IOUT = 100µA; TJ = 25°C, bold values indicate –40°C to +125°C, unless noted.
Parameter
Condition
Min.
Output Voltage Accuracy
Variation from nominal VOUT
–1.0
–3.0
Line Regulation
VIN = VOUT +1V to 6V
–0.3
Load Regulation
IOUT = 0.1mA to 300mA
Typ.
Max.
Units
+1.0
+3.0
%
0.02
+0.3
%/V
1.5
3.0
%
mV
IOUT = 100µA
1
IOUT = 150mA
160
225
275
IOUT = 300mA
340
500
600
IOUT = 0mA
85
150
IOUT = 300mA
100
200
Ground Pin Current in Shutdown
VEN < 0.4V (Regulator OFF)
0.35
1
Ripple Rejection
f = 120Hz, COUT = 2.2µF
Current Limit
VOUT = 0V
Dropout Voltage
Ground Pin Current
300
µA
µA
65
dB
440
mA
Enable Input
Enable Input Voltage
Enable Input Current
Logic low (regulator shutdown)
Logic high (regulator enabled)
0.4
1.6
VIL < 0.4V (regulator shutdown)
0.01
VIH > 1.6V (regulator enabled)
0.01
V
µA
Delay Input
Delay Pin Current Source
Delay Pin Threshold Voltage
0.55
Threshold for RESET = Logic high
1
1.40
µA
V
RESET Output
VTH
Low threshold, % of VOUT (Flag ON)
89
High threshold, % of VOUT (Flag OFF)
91
93
96
0.1
VOL
RESET output logic – low voltage; IRESET = 100µA output
in fault condition
0.020
IRESET
Flag leakage current, Flag OFF
0.01
%
V
µA
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, 1.5kΩ in series with 100pF.
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MIC5249
Functional Diagram
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MIC5249
The capacitor value required can be easily calculated
using the formula:
Application Information
Enable/Shutdown
The MIC5249 comes with an active-high enable pin that
allows the regulator to be disabled. Forcing the enable
pin low disables the regulator and sends it into a “zero”
off-mode-current state. In this state, current consumed
by the regulator goes nearly to zero. Forcing the enable
pin high enables the output voltage. This part is CMOS
and the enable pin cannot be left floating; a floating
enable pin may cause an indeterminate state on the
output.
⎛T
×I
C DELAY = ⎜⎜ DELAY DELAY
V
DELAY
⎝
where IDELAY is 0.55µA and the VDELAY is 1.4V. When no
capacitor is used, there will be no delay and the POR
output acts like a standard error FLAG output.
RESET Output
The RESET output of the MIC5249 provides the poweron reset signal based on the capacitor from the DELAY
pin to ground when input power is applied to the
regulator. The reset signal stays low for a preset time
period after power is applied to the regulator, and then
goes high.
The reset output is an active-low, open-drain output that
drives low when a fault condition AND an undervoltage
detection occurs. Internal circuitry intelligently monitors
overcurrent, overtemperature and dropout conditions
and ORs these outputs together to indicate some fault
condition. The output of that OR gate is ANDed with an
output voltage monitor that detects an undervoltage
condition. The output drives an open-drain transistor to
indicate a fault. This prevents chattering or inadvertent
triggering of the reset. There set must be pulled up using
a resistor form the RESET pin to either the input or the
output.
Input Capacitor
The MIC5249 is a high-performance, high-bandwidth
device. Therefore, it requires a well-bypassed input
supply for optimal performance. A 1.0µF capacitor is
required from the input to ground to provide stability.
Low-ESR
ceramic
capacitors
provide
optimal
performance at a minimum of space. Additional highfrequency capacitors such as small valued NPO
dielectric type capacitors help to filter out high frequency
noise and are good practice in any RF-based circuit.
Output Capacitor
The MIC5249 requires an output capacitor of 2.2µF or
greater to maintain stability. The design is optimized for
use with low-ESR ceramic chip capacitors. High-ESR
capacitors may cause high frequency oscillation. The
maximum recommended ESR is 300mΩ. The output
capacitor can be increased, but performance has been
optimized for a 2.2µF ceramic output capacitor and does
not improve significantly with larger capacitance.
X7R/X5R dielectric-type ceramic capacitors are
recommended
because
of
their
temperature
performance. X7R-type capacitors change capacitance
by 15% over their operating temperature range and are
the most stable type of ceramic capacitors. Z5U and
Y5V dielectric capacitors change value by as much as
50% and 60%, respectively, over their operating
temperature ranges. To use a ceramic chip capacitor
with Y5V dielectric, the value must be much higher than
anX7R ceramic capacitor to ensure the same minimum
capacitance over the equivalent operating temperature
range.
Bypass Pin Input
A bypass capacitor is required from the noise bypass pin
to ground to reduce output voltage noise. The capacitor
bypasses the internal reference. A 0.01µF capacitor is
recommended for applications that require low-noise
outputs. The bypass capacitor can be increased, further
reducing noise and improving PSRR. Turn-on time
increases slightly with respect to bypass capacitance. A
unique quick-start circuit allows the MIC5249 to drive a
large capacitor on the bypass pin without significantly
slowing the turn-on time.
Active Shutdown
The MIC5249 also features an active shutdown clamp,
which is a N-Channel MOSFET that turns on when the
device is disabled. This allows the output capacitor and
load to discharge, de-energizing the load.
DELAY Pin Input
The power-on-reset (POR) function can be implemented
on the MIC5249 by adding an external capacitor from
the DELAY pin to ground. This external capacitor sets
the delay time (TDELAY) of the RESET output.
March 2012
⎞
⎟⎟
⎠
No-Load Stability
The MIC5249 will remain stable and in regulation with no
load unlike many other voltage regulators. This is
especially important in CMOS RAM keep-alive
application.
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Micrel, Inc.
MIC5249
Substituting PD(max) for PD and solving for the operating
conditions that are critical to the application will give the
maximum operating conditions for the regulator circuit.
For example, when operating the MIC5249-3.0YMM at
50°C with a minimum footprint layout, the maximum
input voltage for a set output current can be determined
as follows:
Thermal Considerations
The MIC5249 is designed to provide 300mA of
continuous current in a very small package. Maximum
power dissipation can be calculated based on the output
current and the voltage drop across the device. To
determine the maximum power dissipation of the
package, use the junction-to-ambient thermal resistance
of the device and the following basic equation:
PD(max)
⎛ TJ(max) − TA
= ⎜⎜
θ JA
⎝
⎛ 125°C − 50°C ⎞
PD(max) = ⎜
⎟
⎝ 160°C/W ⎠
⎞
⎟
⎟
⎠
The junction-to-ambient thermal resistance for the
minimum footprint is 160°C/W, from Table 1. The
maximum power dissipation must not be exceeded for
proper operation. Using the output voltage of 3.0V, and
an output current of 300mA, the maximum input voltage
can be determined. Because this device is CMOS and
the ground current is typically 90µA over the load range,
the power dissipation contributed by the ground current
is < 1.0% and can be ignored for this calculation:
TJ(max) is the maximum junction temperature of the die,
125°C and TA is the ambient operating temperature. θJA
is layout dependent; Table 1 shows examples of the
junction-to-ambient thermal resistance for the MIC5249.
Package
MSOP-8
θJA Recommended Minimum Footprint
160°C/W
468mW = (VIN – 3.0V) 300mA
468mW = VIN × 300mA – 900mW
1368mW = VIN × 300mA
VIN(max) = 4.56V
Table 1. MSOP-8 Thermal Resistance
The actual power dissipation of the regulator circuit can
be determined using the equation:
Therefore, a 3.0V application at 300mA of output current
can accept a maximum input voltage of 4.56V in the
MSOP-8 package. For a full discussion of heat sinking
and thermal effects on the voltage regulators, refer to the
“Regulator Thermals” section of Micrel’s Designing with
Low-Dropout Voltage Regulators Handbook.
PD = (VIN – VOUT ) IOUT + VIN IGND
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Micrel, Inc.
MIC5249
Package Information
8-Pin MSOP (MM)
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
Micrel makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this data sheet. This
information is not intended as a warranty and Micrel does not assume responsibility for its use. Micrel reserves the right to change circuitry,
specifications and descriptions at any time without notice. No license, whether express, implied, arising by estoppel or otherwise, to any intellectual
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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
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© 2002 Micrel, Incorporated.
March 2012
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M9999-030812
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