MIC94325/45/55
500 mA LDO with Ripple Blocker Technology
Features
General Description
• 1.8V to 3.6V Input Voltage Range
• Active Noise Rejection over a Wide Frequency
Band
- >50dB from 10 Hz to 5 MHz at 500 mA Load
• Rated to 500 mA Output Current
• Fixed and Adjustable Output Voltages
• Optional Output Auto-Discharge when Disabled
• Current-Limit and Thermal-Limit Protection
• 1.6 mm x 1.6 mm, 6-Pin Thin DFN
• Logic-Controlled Enable Pin
• –40°C to +125°C Junction Temperature Range
The MIC94325, MIC94345, and MIC94355 Ripple
Blocker™ devices are monolithic integrated circuits
that provide low-frequency ripple attenuation
(switching noise rejection) to a regulated output
voltage. This is important for applications where a
DC/DC switching converter is required to lower or raise
a battery voltage, but where switching noise cannot be
tolerated by sensitive downstream circuits such as in
RF applications. The MIC94325/45/55 maintain high
power supply ripple rejection (PSRR) with input
voltages operating near the output voltage level to
improve overall system efficiency. A low-voltage logic
enable pin facilitates ON/OFF control at typical GPIO
voltage levels.
Applications
•
•
•
•
•
•
Smart Phones
Tablet PC/Notebooks and Webcams
Digital Still and Video Cameras
Global Positioning Systems
Mobile Computing
Automotive and Industrial Applications
The MIC94325/45/55 operate from an input voltage of
1.8V to 3.6V. Options include fixed (MIC94345/55) or
adjustable (MIC94325) output voltages. The MIC94355
version offers an auto-discharge to discharge the
output capacitor when the part is disabled.
Packaged in a 6-pin 1.6 mm x 1.6 mm Thin DFN, the
MIC94325/45/55
have
a
junction
operating
temperature range of –40°C to +125°C.
Package Type
MIC94325/45/55
6-Lead TDFN (MT)
(Top View)
VOUT 1
6 VIN
VOUT/ADJ 2
5 VIN
GND 3
2021 Microchip Technology Inc.
EP
4 EN
DS20006524A-page 1
MIC94325/45/55
Typical Application Circuit
MIC943x5
DC/DC
EN
C1
4.7μF
VIN
VOUT
EN
GND
VOUT
C2
4.7μF
Functional Block Diagrams
MIC94345 Fixed Output
MIC94325 Adjustable Output
VIN
VIN
CHARGE
PUMP
EN
BIAS AND
THERMAL
SHUTDOWN
CHARGE
PUMP
VOUT
DRIVER
EA
BIAS AND
THERMAL
SHUTDOWN
EN
VOUT
DRIVER
EA
ADJ
VREF
VREF
GND
GND
MIC94355 Fixed Output with
Auto-Discharge
VIN
CHARGE
PUMP
EN
BIAS AND
THERMAL
SHUTDOWN
VOUT
DRIVER
EA
VREF
GND
DS20006524A-page 2
2021 Microchip Technology Inc.
MIC94325/45/55
1.0
ELECTRICAL CHARACTERISTICS
Absolute Maximum Ratings †
Input Voltage (VIN) ....................................................................................................................................... –0.3V to +4V
Output Voltage (VOUT) ........................................................................................................... –0.3V to VIN + 0.3V or +4V
Enable Voltage (VEN) ............................................................................................................. –0.3V to VIN + 0.3V or +4V
ESD Rating (Note 1) .................................................................................................................................................. 3 kV
Operating Ratings ††
Input Voltage (VIN) .................................................................................................................................... +1.8V to +3.6V
Enable Voltage (VEN) ..........................................................................................................................................0V to VIN
† Notice: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device.
This is a stress rating only and functional operation of the device at those or any other conditions above those indicated
in the operational sections of this specification is not intended. Exposure to maximum rating conditions for extended
periods may affect device reliability.
†† Notice: The device is not guaranteed to function outside its operating ratings.
Note 1: Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5 kΩ in series with
100 pF.
ELECTRICAL CHARACTERISTICS
Electrical Characteristics: VIN = VEN = VOUT + 500 mV (VIN = VEN = 3.6V for VOUT ≥ 3.1V); IOUT = 1 mA;
COUT = 4.7 µF; TA = +25°C, bold values are valid for –40°C ≤ TJ ≤ +125°C, unless noted. Note 1
Parameter
Input Voltage
Output Voltage Range
Output Voltage Accuracy
Adjust Reference
Dropout Voltage
Symbol
Min.
Typ.
Max.
Units
VIN
1.8
—
3.6
V
—
VOUT
1.2
—
3.4
V
MIC94325
—
–3
±1
+3
%
Variation from nominal
VOUT
VADJ
—
1.1
—
V
MIC94325
—
10
—
mV
VDROP
—
100
200
Conditions
VIN to VOUT dropout at
50 mA output current
VIN to VOUT dropout at
500 mA output current
Load Regulation
ΔVOUT
—
10
—
mV
1 mA to 500 mA
Line Regulation
(ΔVOUT/VOUT)
x 100%/ΔVIN
—
0.1
1
%/V
VIN = VOUT + 500 mV to
3.6V, IOUT = 100 mA
Ground Current
IGND
—
170
250
µA
IOUT = 100 µA
IEN
—
0.2
5
µA
VEN = 0V
—
85
—
f = 100 Hz
—
85
—
f = 1 kHz
—
57
—
—
60
—
f = 1 MHz
—
50
—
f = 5 MHz
ILIMIT
530
800
1100
Total Output Noise
eN
—
83
—
Turn-On Time
tON
—
100
150
Shutdown Current
VIN Ripple Rejection
Current Limit
Note 1:
PSRR
dB
mA
f = 100 kHz
VOUT = 0V
µVRMS 10 Hz to 100 kHz
µs
—
Specification for packaged product only.
2021 Microchip Technology Inc.
DS20006524A-page 3
MIC94325/45/55
ELECTRICAL CHARACTERISTICS (CONTINUED)
Electrical Characteristics: VIN = VEN = VOUT + 500 mV (VIN = VEN = 3.6V for VOUT ≥ 3.1V); IOUT = 1 mA;
COUT = 4.7 µF; TA = +25°C, bold values are valid for –40°C ≤ TJ ≤ +125°C, unless noted. Note 1
Parameter
Symbol
Min.
Typ.
Max.
Units
Conditions
RDS
—
50
—
Ω
VIN = 3.6V, VEN = 0V, IOUT
= –3 mA
MIC94355 Only
Input Logic Low
VEN-LOW
—
—
0.35
V
—
Input Logic High
VEN_HIGH
1.0
—
—
V
—
IIN
—
0.01
1
µA
—
Auto Discharge NFET
Resistance
Enable
Input Current
Note 1:
Specification for packaged product only.
TEMPERATURE SPECIFICATIONS
Parameters
Sym.
Min.
Typ.
Max.
Units
Conditions
Junction Temperature Range
TJ
–40
—
+125
°C
—
Storage Temperature Range
TS
–65
—
+150
°C
—
Lead Temperature
—
—
—
+260
°C
Soldering, 10 sec.
JA
—
92
—
°C/W
Temperature Ranges
Package Thermal Resistances
Thermal Resistance, TDFN 6-Ld
Note 1:
—
The maximum allowable power dissipation is a function of ambient temperature, the maximum allowable
junction temperature and the thermal resistance from junction to air (i.e., TA, TJ, JA). Exceeding the
maximum allowable power dissipation will cause the device operating junction temperature to exceed the
maximum +125°C rating. Sustained junction temperatures above +125°C can impact the device reliability.
DS20006524A-page 4
2021 Microchip Technology Inc.
MIC94325/45/55
TYPICAL PERFORMANCE CURVES
The graphs and tables provided following this note are a statistical summary based on a limited number of
samples and are provided for informational purposes only. The performance characteristics listed herein
are not tested or guaranteed. In some graphs or tables, the data presented may be outside the specified
operating range (e.g., outside specified power supply range) and therefore outside the warranted range.
-20
-20
-30
-30
-40
-40
PSRR (dB)
-50
500mA
-60
300mA
-70
-80
10mA
10
100
1K
10K
100K
1.00E+03
1.00E+05
FREQUENCY (Hz)
10mA
500mA
-120
1M
1010
10M
1.00E+07
FIGURE 2-1:
MIC94325 PSRR, COUT =
4.7 µF, CFF = 10 nF.
100 1,000
1K 10,000
10K 100,00
100K1,000,0
1M 10,000,
10M
100
0
00
000
FREQUENCY (Hz)
FIGURE 2-4:
MIC94325 PSRR, COUT =
4.7 µF, CFF = 100 nF.
0
-20
V IN = 2.7V + 40mvpp
-30
VIN = 2.5V + 40mvpp
V OUT = 2.2V
-40
PSRR (dB)
-80
-110
CFF = 10nF
-120
1.00E+01
300mA
-70
-100
COUT = 4.7μF
-110
CFF = 100nF
-90
V OUT = 2.2V
-100
VOUT = 2.2V
COUT = 4.7μF
-60
V IN = 2.4V + 40mvpp
-90
VIN = 2.7V + 40mvpp
-50
PSRR (dB)
Note:
COUT = 4.7μF
500mA
-50
COUT = 4.7μF
CFF = 3.3nF
-60
VOUT = 1.8V
-20
300mA
-70
-80
10mA
-60
10mA
-80
-90
-100
-100
-110
-120
200mA
10
10
100
100
1K
10K
100K
1M
10M
1,000 10,000 100,00 1,000,0 10,000,
0
00
000
FREQUENCY (Hz)
FIGURE 2-2:
MIC94325 PSRR, COUT =
4.7 µF, CFF = 3.3 nF.
-120
10
10
10K 100,00
100K 1,000,0
1M 10,000,
10M
10,000
000
MIC94355 PSRR, COUT =
0
VIN = 2.8V + 40mVpp
-20
-40
-50
-60
300mA
-70
-80
V IN = 2.7V + 40mvpp
-90
V OUT = 2.2V
-100
COUT = 4.7μF
CFF = 10nF
10mA
10
10
100
100
VOUT = 1.8V
COUT = 4.7μF
500mA
PSRR (dB)
PSRR (dB)
1K
1,000
FIGURE 2-5:
4.7 µF.
-30
-120
100
100
0
00
FREQUENCY (Hz)
-20
-110
500mA
-40
PSRR (dB)
2.0
1K
1,000
10K 100,00
100K 1,000,0
1M 10,000,
10M
10,000
0
00
000
FREQUENCY (Hz)
FIGURE 2-3:
MIC94325 PSRR, COUT =
4.7 µF, CFF = 10 nF.
2021 Microchip Technology Inc.
-40
500mA
-60
10mA
-80
-100
200mA
-120
10
100
1,000
1K
10,000
10K 100,00
100K 1,000,0
1M 10,000,
10M
0
00
000
FREQUENCY (Hz)
FIGURE 2-6:
4.7 µF.
MIC94355 PSRR, COUT =
DS20006524A-page 5
MIC94325/45/55
0
0
VIN = 3.6V + 40mVpp
VIN = 3.6V + 40mVpp
-20
COUT = 4.7μF
COUT = 10μF
200mA
-40
500mA
-60
-80
10mA
-40
PSRR (dB)
PSRR (dB)
VOUT = 1.8V
-20
VOUT = 1.8V
200mA
-60
-80
10mA
100mA
-100
-100
-120
-120
10
100
1K
1,000
10K 100,00
100K 1,000,0
1M 10,000,
10M
10,000
0
00
000
10
100
FIGURE 2-7:
4.7 µF.
MIC94355 PSRR, COUT =
1K
1,000
10K 100,00
100K 1,000,0
1M 10,000,
10M
10,000
00
000
0
FREQUENCY (Hz)
FREQUENCY (Hz)
FIGURE 2-10:
10 µF.
0
MIC94355 PSRR, COUT =
2
VIN = 2.5V + 40mVpp
10mA
COUT = 10μF
PSRR (dB)
-40
200mA
500mA
-60
OUTPUT VOLTAGE (V)
1.95
VOUT = 1.8V
-20
1.9
1.85
1.8
1.75
-80
-100
1.7
VIN = 2.8V
1.65
-120
10
10
100
100
1,000
1K
CIN = COUT = 4.7μF
1.6
10,000
10K 100,00
100K 1,000,0
1M 10,000,
10M
0
00
000
0
50 100 150 200 250 300 350 400 450 500
FREQUENCY (Hz)
MIC94355 PSRR, COUT =
FIGURE 2-8:
10 µF.
Output Voltage vs. Output
100
0
V OUT = 1.8V
COUT = 10μF
200mA
-40
500mA
-60
-80
10mA
-100
DROPOUT VOLTAGE (mV)
V IN = 2.8V + 40mVpp
-20
PSRR (dB)
OUTPUT CURRENT (mA)
FIGURE 2-11:
Current.
90
80
70
60
50
40
30
20
VOUT = 1.8V
10
-120
10
100
1,000
1K
10,000
10K 100,00
100K 1,000,0
1M 10,000,
10M
0
00
000
CIN = COUT = 4.7μF
0
0
50 100 150 200 250 300 350 400 450 500
FREQUENCY(Hz)
FIGURE 2-9:
10 µF.
DS20006524A-page 6
MIC94355 PSRR, COUT =
LOAD (mA)
FIGURE 2-12:
Dropout Voltage vs. Load.
2021 Microchip Technology Inc.
MIC94325/45/55
200
10
GROUND CURRENT (μA)
195
190
1
NOISE μV/¥Hz
185
180
175
170
165
0.1
0.01
VIN = VEN = 3V
160
COUT = 4.7μF/10V
155
0.001
150
0
50 100 150 200 250 300 350 400 450 500
FIGURE 2-13:
Current.
1010
100 1,0001K 10,000
10K100,00
100K
1M10,000,
10M
100
1,000,0
0
00
000
FREQUENCY (Hz)
OUTPUT CURRENT (mA)
Ground Current vs. Output
FIGURE 2-15:
MIC94355YMT Output
Noise Spectral Density.
220
500mA
GROUND CURRENT (μA)
210
200
300mA
190
180
170
100mA
50mA
160
150
140
CIN = COUT = 1μF
130
120
1.8
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
INPUT VOLTAGE (V)
FIGURE 2-14:
Voltage.
Ground Current vs. Input
2021 Microchip Technology Inc.
DS20006524A-page 7
MIC94325/45/55
FIGURE 2-16:
Load Transient.
FIGURE 2-18:
Turn-On Time.
FIGURE 2-17:
Line Transient.
FIGURE 2-19:
(Auto-Discharge).
Turn-Off Time
DS20006524A-page 8
2021 Microchip Technology Inc.
MIC94325/45/55
3.0
PIN DESCRIPTIONS
The descriptions of the pins are listed in Table 3-1.
TABLE 3-1:
PIN FUNCTION TABLE
Pin Number
TDFN, Fixed
Pin Number
TDFN, Adj.
Pin Name
1, 2
1
VOUT
—
2
ADJ
Adjust input. Connect to resistive divider at VOUT to set the output
voltage. Do not leave floating.
3
3
GND
Ground.
4
4
EN
Enable Input. A logic HIGH signal on this pin enables the part. Logic
LOW disables the part. Do not leave floating.
5, 6
5, 6
VIN
Power Switch Input and Chip Supply.
EP
EP
ePAD
2021 Microchip Technology Inc.
Description
Power Switch Output.
Exposed Heatsink Pad. Connect to Ground plane for best thermal
performance.
DS20006524A-page 9
MIC94325/45/55
4.0
APPLICATION INFORMATION
The MIC943x5 family of products are very high PSRR,
fixed-output, 500 mA LDOs that use Ripple Blocker™
technology. The MIC943x5 are fully protected from
damage due to fault conditions, offering linear current
limiting and thermal shutdown.
4.1
Input Capacitor
The MIC943x5 are high-performance, high-bandwidth
devices. An input capacitor of 4.7 µF is required from
the input to ground to provide stability. Low-ESR
ceramic capacitors provide optimal performance at a
minimum of space. Additional high-frequency
capacitors, such as small-valued NPO dielectric-type
capacitors, help filter out high-frequency noise and are
good practice in any RF-based circuit. X5R or X7R
dielectrics are recommended for the input capacitor.
Y5V dielectrics lose most of their capacitance over
temperature and are therefore, not recommended.
4.2
Output Capacitor
In order to maintain stability, the MIC943x5 require an
output capacitor of 4.7 µF or greater. For optimal input
voltage ripple rejection performance a 4.7 µF capacitor
is recommended. The design is optimized for use with
low-ESR ceramic chip capacitors. High-ESR
capacitors are not recommended because they may
cause high-frequency oscillation. The output capacitor
can be increased, but performance has been optimized
for a 4.7 µF 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 their value by as
much as 50% and 60%, respectively, over their
operating temperature ranges. To use a ceramic chip
capacitor with the Y5V dielectric, the value must be
much higher than an X7R ceramic capacitor to ensure
the same minimum capacitance over the equivalent
operating temperature range.
4.3
The EN pin uses CMOS technology and cannot be left
floating as it could cause an indeterminate state on the
output.
For the MIC94325 adjustable part, the turn-on time is
affected by the selection of the external feedback
resistors and feed-forward capacitor. The relationship
is approximately 2.2 x R2 x CFF, where R2 is the bottom
resistor (connected from ADJ to GND) and CFF is the
capacitor connected across R1 (from VOUT to ADJ).
For stability, the feed-forward capacitor must be greater
than 1 nF. 10 nF is recommended for best
performance.
When disabled, the MIC94355 switches a 50Ω (typical)
load on the regulator output to discharge the external
capacitors.
4.5
Adjustable Regulator Application
The MIC94325 output voltage can be adjusted by using
two external resistors (Figure 4-1). The resistors set
the output voltage based on the following equation:
EQUATION 4-1:
V OUT = V ADJ 1 + R1
-------
R2
V ADJ = 1.1V
U1
MIC94325YMT
6
VIN
VIN
VOUT
1
VOUT
C3
10nF
R1
C1
4.7μF
5
EN
4
VIN
EN
ADJ
GND
2
3
C2
4.7μF
R2
GND
FIGURE 4-1:
Adjustable Output Voltage.
No Load Stability
The MIC943x5 will remain stable and in regulation with
no load. This is especially important in CMOS RAM
keep-alive applications.
4.4
Enable/Shutdown
Forcing the enable (EN) pin low disables the MIC943x5
and sends it into a “zero” off mode current state. In this
state, current consumed by the MIC943x5 goes nearly
to zero. Forcing EN high enables the output voltage.
DS20006524A-page 10
2021 Microchip Technology Inc.
MIC94325/45/55
4.6
Thermal Considerations
The MIC943x5 are designed to provide 500 mA of
continuous current in a very small package. Maximum
ambient operating temperature can be calculated
based on the output current and the voltage drop
across the part. For example if the input voltage is 2.5V,
the output voltage is 1.8V, and the output current is
500 mA. The actual power dissipation of the Ripple
Blocker™ can be determined using the equation:
EQUATION 4-2:
P D = V IN – V OUT1 I OUT + V IN I GND
Because this device is CMOS and the ground current
is typically
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