RT9184A - Richtek
RT9184A
Dual, Ultra-Fast Transient Response, 500mA LDO Regulator
General Description
Features
The RT9184A series are an efficient, precise dual-channel
CMOS LDO regulator optimized for ultra-low-quiescent
applications. Both regulator outputs are capable of sourcing
500mA of output current.
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The RT9184A's performance is optimized for CD/DVD-ROM,
CD/RW or wireless communication supply applications.
The RT9184A regulators are stable with output capacitors
as low as 1μF. The other features include ultra low dropout
voltage, high output accuracy, current limiting protection,
and high ripple rejection ratio.
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The RT9184A regulators are available in fused SOP-8
package. Key features include current limit, thermal
shutdown, fast transient response, low dropout voltage,
high output accuracy, current limiting protection, and high
ripple rejection ratio.
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μA)
Low Quiescent Current (Typically 440μ
Guaranteed 500mA Output Current
Low Dropout Voltage : 600mV at 500mA
Wide Operating Voltage Ranges : 2.8V to 5.5V
Ultra-Fast Transient Response
Tight Load and Line Regulation
Current Limiting Protection
Thermal Shutdown Protection
Only low-ESR Ceramic Capacitors Required for
Stability
Custom Voltage Available
RoHS Compliant and 100% Lead (Pb)-Free
Ordering Information
RT9184APackage Type
S : SOP-8
Applications
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CD/DVD-ROM, CD/RW
Wireless LAN Card/Keyboard/Mouse
Battery-Powered Equipment
XDSL Router
Lead Plating System
P : Pb Free
G : Green (Halogen Free and Pb Free)
Note :
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Pin Configurations
(TOP VIEW)
VOUT1
8
GND
VIN1
2
7
GND
VOUT2
3
6
GND
VIN2
4
5
GND
Output 2
Output 1
The output 2 is designated to larger than or equal to
output 1 in voltage code order below, i.e. VOUT2 ≥ VOUT1.
For example, the part number of RT9184A-FNCS is
assigned for 2.5VOUT1/3.3VOUT2, contrary to the part
number of RT9184A-NFCS is opposite to the rule and
doesn't exist in the system.
Voltage Code for Both Outputs :
2: 1.2V
A: 2.0V
K: 3.0V
U: 4.0V
3: 1.3V
B: 2.1V
L: 3.1V
V: 4.1V
4: 1.4V
C: 2.2V
M: 3.2V
W: 4.2V
SOP-8
:
:
9: 1.9V
J: 2.9V
:
T: 3.9V
:
Z: 4.5V
RichTek products are :
`
RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020.
`
DS9184A-09 April 2011
Suitable for use in SnPb or Pb-free soldering processes.
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RT9184A
Typical Application Circuit
VOUT2
VOUT2 VOUT1
1uF
VOUT1
1uF
VIN2
1uF
dielectric is strongly recommended if ceramics are used
as input/output capacitors. When using the Y5V dielectric,
RT9184A
VIN2
μF minimum X7R or X5R
Note: To prevent oscillation, a 1μ
the minimum value of the input/output capacitance that
VIN1
VIN1
can be used for stable over full operating temperature
1uF
GND
range is 3.3μ
μF. (see Application Information Section for
further details)
Function Block Diagram
VIN1
VOUT1
Error
Amplifier
-
+
Current
Limiting
Sensor
Thermal
Shutdown
1.2V
Reference
VOUT2
VIN2
Error
Amplifier
-
+
Current
Limiting
Sensor
Thermal
Shutdown
1.2V
Reference
GND
Functional Pin Description
Pin No.
Pin Name
Pin Function
1
VOUT1
Channel 1 Output Voltage
2
VIN1
Channel 1 Supply Input
5,6,7,8
GND
Common Ground
3
VOUT2
Channel 2 Output Voltage
4
VIN2
Channel 2 Supply Input
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DS9184A-09 April 2011
RT9184A
Absolute Maximum Ratings
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(Note 1)
Supply Input Voltage ------------------------------------------------------------------------------------------------ 6.5V
Power Dissipation, PD @ TA = 25°C
SOP-8 ------------------------------------------------------------------------------------------------------------------ 0.625W
Package Thermal Resistance (Note 2)
SOP-8, θJA ------------------------------------------------------------------------------------------------------------ 160°C/W
Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------- 260°C
Junction Temperature ----------------------------------------------------------------------------------------------- 150°C
Storage Temperature Range --------------------------------------------------------------------------------------- −65°C to 150°C
ESD Susceptibility (Note 3)
HBM (Human Body Mode) ----------------------------------------------------------------------------------------- 2kV
MM (Machine Mode) ------------------------------------------------------------------------------------------------ 200V
Recommended Operating Conditions
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(Note 4)
Supply Input Voltage ------------------------------------------------------------------------------------------------ 2.8V to 5.5V
Junction Temperature Range -------------------------------------------------------------------------------------- −40°Cto 125°C
Electrical Characteristics
(VIN = VOUT + 1V, or VIN = 2.8V whichever is greater, CIN = 1μF, COUT = 1μF, TA = 25°C, for each LDO unless otherwise specified)
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
Output Voltage Accuracy
ΔV OUT
IOUT = 1mA
−1
--
3
%
Current Limit
ILIM
RLOAD = 1Ω
500
--
--
mA
Quiescent Current (both LDOs)
(Note 5)
IQ
IOUT = 0mA
--
440
600
μA
Dropout Voltage
VDROP
IOUT = 500mA
--
600
--
mV
ΔV LINE
VIN = (VOUT + 0.3V) to 5.5V,
--
0.2
--
%/V
(Note 6)
Line Regulation
IOUT = 1mA
ΔV LOAD
1mA < IOUT < 500mA
--
30
--
mV
Power Supply Rejection Rate
PSRR
f = 1kHz, C OUT = 1μF
--
−55
--
dB
Thermal Shutdown Protection
TSD
--
170
--
°C
Thermal Shutdown Hysteresis
ΔT SD
--
40
--
°C
Load Regulation
(Note 7)
DS9184A-09 April 2011
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RT9184A
Note 1. Stresses listed as the above “Absolute Maximum Ratings” may cause permanent damage to the device. These are
for stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the
operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended
periods may remain possibility to affect device reliability.
Note 2. θ JA is measured in the natural convection at TA = 25°C on a low effective thermal conductivity test board of
JEDEC 51-3 thermal measurement standard.
Note 3. Devices are ESD sensitive. Handling precaution recommended.
Note 4. The device is not guaranteed to function outside its operating conditions.
Note 5. Regulation is measured at constant junction temperature by using a 20ms current pulse. Devices are tested for load
regulation in the load range from 1mA to 500mA.
Note 6. The dropout voltage is defined as VIN -VOUT, which is measured when VOUT is VOUT(NORMAL) − 100mV.
Note 7. Quiescent, or ground current, is the difference between input and output currents. It is defined by IQ = IIN - IOUT under no
load condition (IOUT = 0mA). The total current drawn from the supply is the sum of the load current plus the ground pin
current.
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DS9184A-09 April 2011
RT9184A
Typical Operating Characteristics
Output Voltage vs. Temperature
Quiescent Current vs. Temperature
500
3.35
VIN1 = VIN2 = 5V
CIN1 = CIN2 = 1uF
COUT1 = COUT2 = 1uF
RL1 = RL2 = ∞
A
VIN1 = 5V
CIN1 = 1uF
COUT1 = 1uF
RL1 = ∞
Quiescent Current (uA)
Output Voltage (V)
3.4
3.3
3.25
3.2
450
400
350
300
-50
-40
-25
0
25
50
75
100
125
-50
-40
-25
0
Temperature (°C)
75
100
125
Current Limit vs. Temperature
Current Limit vs. Input Voltage
900
VIN1 = 5V
CIN1 = 1uF
COUT1 = 1uF
RL1 = 0.5Ω
850
Current Limit (mA)
Current Limit (mA)
50
Temperature (°C)
900
800
750
VIN1 = 5V
CIN1 = 1uF
COUT1 = 1uF
RL1 = 0.5Ω
850
800
750
700
700
3
3.5
4
4.5
5
-50
-40
5.5
Input Voltage (V)
≈
≈
≈
IOUT2
VOUT2
VOUT1
(20mV/Div) (20mV/Div) (100mA/Div)
≈
DS9184A-09 April 2011
0
25
50
75
100
125
Load Transient Regulation
VIN1 = VIN2 = 5V, CIN1 = CIN2 = 1uF(X7R)
COUT1 = COUT2 = 1uF(X7R), IOUT2 = 0A
Time (1ms/Div)
-25
Temperature (°C)
Load Transient Regulation
IOUT1
VOUT2
VOUT1
(20mV/Div) (20mV/Div) (100mA/Div)
25
VIN1 = VIN2 = 5V, CIN1 = CIN2 = 1uF(X7R)
COUT1 = COUT2 = 1uF(X7R), IOUT1 = 0A
≈
≈
≈
≈
Time (1ms/Div)
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RT9184A
Dropout Voltage vs. Output Current
Power Supply Rejection Ratio
0
800
CIN1 = 10uF
COUT1 = 10uF
700
-10
TJ = 125°C
PSRR (dB)
Dropout Voltage (mA)
600
500
TJ = 25°C
400
TJ = -40°C
300
VIN1 = 5V
CIN1 = 10uF
COUT1 = 10uF
-20
-30
-40
100mA
1mA
200
-50
100
-60
0
0
100
200
300
400
10
500
100
1k
1000
10k
10000
100k
100000
1M
1000000
Frequency (Hz)
Output Current (mA)
Range of Stable ESR
Line Transient Regulation
Input Voltage
Deviation (V)
10
10uF
Unstable Range
Output Voltage
Deviation (mV)
Output Capacitor ESR ( Ω )
100
1
Stable Range
1uF
0.1
VIN1 = 3 to 4V
VIN2 = 5V
CIN1 = 10uF
COUT1 = 10uF
4
3
≈
≈
2
0
-2
0.01
0
100
200
300
400
500
Time (1ms/Div)
Output Current (mA)
Output Noise
Output Noise Signal (uV)
VIN1 = 5V
ILOAD = 100mA
CIN1 = 1uF
COUT1 = 1uF
4
3
2
0
-2
F = 10Hz to 100kHz
Time (1ms/Div)
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DS9184A-09 April 2011
RT9184A
Application Information
Like any low-dropout regulator, the RT9184A requires input
and output decoupling capacitors. The device is specifically
designed for portable applications requiring minimum board
space and smallest components. These capacitors must
be correctly selected for good performance (see Capacitor
Characteristics Section). Please note that linear regulators
with a low dropout voltage have high internal loop gains
which require care in guarding against oscillation caused
by insufficient decoupling capacitance.
Input Capacitor
An input capacitance of ≅1μF is required between the
device input pin and ground directly (the amount of the
capacitance may be increased without limit). The input
capacitor MUST be located less than 1cm from the device
to assure input stability (see PCB Layout Section). A lower
ESR capacitor allows the use of less capacitance, while
higher ESR type (like aluminum electrolytic) require more
capacitance.
Capacitor types (aluminum, ceramic and tantalum) can
be mixed in parallel, but the total equivalent input
capacitance/ESR must be defined as above to stable
operation.
There are no requirements for the ESR on the input
capacitor, but tolerance and temperature coefficient must
be considered when selecting the capacitor to ensure the
capacitance will be ≅1μF over the entire operating
temperature range.
Output Capacitor
The RT9184A is designed specifically to work with very
small ceramic output capacitors. The recommended
minimum capacitance (temperature characteristics X7R
or X5R) are 1μF to 4.7μF range with 10mΩ to 50mΩ range
ceramic capacitors between each LDO output and GND
for transient stability, but it may be increased without limit.
Higher capacitance values help to improve transient.
The output capacitor's ESR is critical because it forms a
zero to provide phase lead which is required for loop
stability. (When using the Y5V dielectric, the minimum
value of the input/output capacitance that can be used for
stable over full operating temperature range is 3.3μF.)
DS9184A-09 April 2011
No Load Stability
The device will remain stable and in regulation with no
external load. This is specially important in CMOS RAM
keep-alive applications.
Input-Output (Dropout) Voltage
A regulator's minimum input-to-output voltage differential
(dropout voltage) determines the lowest usable supply
voltage. In battery-powered systems, this determines the
useful end-of-life battery voltage. Because the device uses
a PMOS, its dropout voltage is a function of drain-tosource on-resistance, RDS(ON), multiplied by the load
current :
VDROPOUT = VIN − VOUT = RDS(ON) × IOUT
Current Limit
The RT9184A monitors and controls the PMOS' gate
voltage, limiting the output current to 500mA (min.). The
output can be shorted to ground for an indefinite period of
time without damaging the part.
Short-Circuit Protection
The device is short circuit protected and in the event of a
peak over-current condition, the short-circuit control loop
will rapidly drive the output PMOS pass element off. Once
the power pass element shuts down, the control loop will
rapidly cycle the output on and off until the average power
dissipation causes the thermal shutdown circuit to
respond to servo the on/off cycling to a lower frequency.
Please refer to the section on thermal information for power
dissipation calculations.
Capacitor Characteristics
It is important to note that capacitance tolerance and
variation with temperature must be taken into consideration
when selecting a capacitor so that the minimum required
amount of capacitance is provided over the full operating
temperature range. In general, a good tantalum capacitor
will show very little capacitance variation with temperature,
but a ceramic
may not be as good (depending on dielectric type).
Aluminum electrolytics also typically have large
temperature variation of capacitance value.
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RT9184A
Equally important to consider is a capacitor's ESR change
with temperature: this is not an issue with ceramics, as
their ESR is extremely low. However, it is very important
in tantalum and aluminum electrolytic capacitors. Both
show increasing ESR at colder temperatures, but the
increase in aluminum electrolytic capacitors is so severe
they may not be feasible for some applications.
Ceramic :
For values of capacitance in the 10μF to 100μF range,
ceramics are usually larger and more costly than tantalums
but give superior AC performance for by-passing high
frequency noise because of very low ESR (typically less
than 10mΩ). However, some dielectric types do not have
good capacitance characteristics as a function of voltage
and temperature.
Z5U and Y5V dielectric ceramics have capacitance that
drops severely with applied voltage. A typical Z5U or Y5V
capacitor can lose 60% of its rated capacitance with half
of the rated voltage applied to it. The Z5U and Y5V also
exhibit a severe temperature effect, losing more than 50%
of nominal capacitance at high and low limits of the
temperature range.
X7R and X5R dielectric ceramic capacitors are strongly
recommended if ceramics are used, as they typically
maintain a capacitance range within ±20% of nominal over
full operating ratings of temperature and voltage. Of course,
they are typically larger and more costly than Z5U/Y5U
types for a given voltage and capacitance.
Tantalum :
Solid tantalum capacitors are recommended for use on
the output because their typical ESR is very close to the
ideal value required for loop compensation. They also work
well as input capacitors if selected to meet the ESR
requirements previously listed.
Tantalums also have good temperature stability: a good
quality tantalum will typically show a capacitance value
that varies less than 10~15% across the full temperature
range of 125°C to -40°C. ESR will vary only about 2X going
from the high to low temperature limits.
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8
The increasing ESR at lower temperatures can cause
oscillations when marginal quality capacitors are used (if
the ESR of the capacitor is near the upper limit of the
stability range at room temperature).
Aluminum :
This capacitor type offers the most capacitance for the
money. The disadvantages are that they are larger in
physical size, not widely available in surface mount, and
have poor AC performance (especially at higher
frequencies) due to higher ESR and ESL.
Compared by size, the ESR of an aluminum electrolytic
is higher than either Tantalum or ceramic, and it also varies
greatly with temperature. A typical aluminum electrolytic
can exhibit an ESR increase of as much as 50X when
going from 25°C down to -40°C.
It should also be noted that many aluminum electrolytics
only specify impedance at a frequency of 120Hz, which
indicates they have poor high frequency performance. Only
aluminum electrolytics that have an impedance specified
at a higher frequency (between 20kHz and 100kHz) should
be used for the device. Derating must be applied to the
manufacturer's ESR specification, since it is typically only
valid at room temperature.
Any applications using aluminum electrolytics should be
thoroughly tested at the lowest ambient operating
temperature where ESR is maximum.
PCB Layout
Good board layout practices must be used or instability
can be induced because of ground loops and voltage drops.
The input and output capacitors MUST be directly
connected to the input, output, and ground pins of the
device using traces which have no other currents flowing
through them.
The best way to do this is to layout CIN and COUT near the
device with short traces to the VIN, VOUT, and ground pins.
The regulator ground pin should be connected to the
external circuit ground so that the regulator and its
capacitors have a “ single point ground”.
DS9184A-09 April 2011
RT9184A
It should be noted that stability problems have been seen
in applications where “ vias” to an internal ground plane
were used at the ground points of the device and the input
and output capacitors. This was caused by varying ground
potentials at these nodes resulting from current flowing
through the ground plane. Using a single point ground
technique for the regulator and it's capacitors fixed the
problem. Since high current flows through the traces going
into VIN and coming from VOUT, Kelvin connect the capacitor
leads to these pins so there is no voltage drop in series
with the input and output capacitors.
Optimum performance can only be achieved when the
device is mounted on a PC board according to the diagram
below :
GND
+
+
VOUT1
VIN2
+
GND
+
VIN1
VOUT2
GND
SOP-8 Board Layout
DS9184A-09 April 2011
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9
RT9184A
Outline Dimension
H
A
M
J
B
F
C
I
D
Dimensions In Millimeters
Dimensions In Inches
Symbol
Min
Max
Min
Max
A
4.801
5.004
0.189
0.197
B
3.810
3.988
0.150
0.157
C
1.346
1.753
0.053
0.069
D
0.330
0.508
0.013
0.020
F
1.194
1.346
0.047
0.053
H
0.170
0.254
0.007
0.010
I
0.050
0.254
0.002
0.010
J
5.791
6.200
0.228
0.244
M
0.400
1.270
0.016
0.050
8-Lead SOP Plastic Package
Richtek Technology Corporation
Richtek Technology Corporation
Headquarter
Taipei Office (Marketing)
5F, No. 20, Taiyuen Street, Chupei City
5F, No. 95, Minchiuan Road, Hsintien City
Hsinchu, Taiwan, R.O.C.
Taipei County, Taiwan, R.O.C.
Tel: (8863)5526789 Fax: (8863)5526611
Tel: (8862)86672399 Fax: (8862)86672377
Email: [email protected]
Information that is provided by Richtek Technology Corporation is believed to be accurate and reliable. Richtek reserves the right to make any change in circuit
design, specification or other related things if necessary without notice at any time. No third party intellectual property infringement of the applications should be
guaranteed by users when integrating Richtek products into any application. No legal responsibility for any said applications is assumed by Richtek.
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10
DS9184A-09 April 2011
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