RT9184 [RICHTEK]
500 MA DUAL LDO REGULATOR; 500毫安双LDO稳压器
| 型号： | RT9184 |
| 厂家： | 
RICHTEK TECHNOLOGY CORPORATION |
| 描述： | 500 MA DUAL LDO REGULATOR |
| 文件： | 总10页 (文件大小：187K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Preliminary
RT9184
500mA Dual LDO Regulator
General Description
Features
The RT9184 is a dual-channel, low noise, and low
dropout regulator supplying up to 500mA current at
each channel. The output voltage ranges from 1.5V
to 3.3V in 100mV increment and 2% accuracy by
operating from a +2.7V to +6.5V input.
z Up to 500mA Output Current (Each LDO)
z Current Limiting and Thermal Protection
z Short Circuit Protection
z 650mV Dropout at 500mA Load
z Two LDOs in Power SOP-8 Package
The RT9184 uses two internal PMOS as the pass
device, which consumes 185µA supply current (both
LDOs on) independent of load current and dropout
conditions. Other features include a current limiting
and over temperature protection.
Pin Configurations
Part Number
Pin Configurations
TOP VIEW
RT9184ꢀCH
(Plastic PSOP-8)
1
2
3
4
8
7
6
5
VIN
VIN
GND
GND
Applications
GND
VOUT1
NC
z Desktop Computers
z CD-RW
VOUT2
z LCD Monitor
z Information Appliance
Typical Application Circuit
Ordering Information
RT9184ꢀ ꢀ ꢀ
V
OUT2
VOUT1
VIN
V
OUT1
VOUT2
Package type
Operating temperature range
C : Commercial standard
RT9184
GND
µ
10 F
µ
10 F
µ
10 F
Output voltage
A : 3.3V (Output1), 1.8V (Output2)
B : 3.3V (Output1), 2.5V (Output2)
Other voltage versions please
contact RichTek for detail.
DS9184-00 March 2002
www.richtek-ic.com.tw
1
RT9184
Preliminary
Pin Description
Pin Name
Pin Function
Power Input
Ground
VIN
GND
VOUT1
VOUT2
NC
Output1 Voltage
Output2 Voltage
No Connected
Function Block Diagram
Current Limit
Thermal Protection
Vref
Current Limit
VIN
_
_
VOUT1
VOUT2
GND
Bias
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DS9184-00 March 2002
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Preliminary
RT9184
Absolute Maximum Ratings
z Input Voltage
7V
z Package Thermal Resistance
PSOP-8, θ
28°C/W
JC
z Junction Temperature Range
z Storage Temperature Range
z Operating Temperature Range
z Lead Temperature (Soldering, 10 sec.)
-40°C ~ 125°C
-65°C ~ 150°C
-40°C ~ 85°C
260°C
Electrical Characteristics
(V = 5V, C = C
= 10µF, typical values at T = 25°C, for each LDO unless otherwise specified.)
A
IN
IN
OUT
Parameter
Symbol
Test Conditions
Min
Typ
Max
Units
Input Voltage Range
2.7
--
6.5
V
V
IN
Output Voltage Accuracy
-2
--
+2
%
∆V
I
= 1mA
OUT
MAX
OUT
Maximum Output Current
Current Limit
Continuous
= 1Ω
500
510
--
--
--
1000
260
--
mA
mA
µA
I
I
I
--
R
LIMIT
G
LOAD
GND Pin Current (Whole Chip)
No Load
I = 500mA
OUT
185
650
Note
--
mV
Dropout Voltage
V
DROP
V
OUT
= (V
+0.4V or 2.7V) to 6.5V
IN
OUT
= 1mA
Line Regulation
-0.2
--
+0.2
%/V
∆V
LINE
I
Load Regulation
-35
125
--
-20
180
20
+5
--
mV
°C
∆V
I
= 1mA to 500mA
LOAD OUT
Thermal Shutdown Temperature
Thermal Shutdown Hysteresis
--
T
°C
SD
100Hz, C
LOAD
= 10µF
OUT
= 100mA
Output Voltage AC PSRR
--
62
--
dB
I
Note : Dropout voltage definition: V – V
when V
is 50mV below the value of V (normal)
OUT
IN
OUT
OUT
DS9184-00 March 2002
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3
RT9184
Preliminary
Typical Operating Characteristics
I
= 100mA, V = 5V, C
= 10µF, and C = 10µF, unless otherwise noted.
OUT IN
LOAD
IN
Quiescent Current vs. Temp.
Output Voltage Accuracy vs. Temp.
200
180
160
140
120
100
1.0
0.8
0.6
0.4
0.2
0.0
-0.2
-0.4
-0.6
-0.8
-1.0
-40
-15
10
35
60
85
-40
-15
10
35
60
85
°
Temperature ( C)
°
Temperature ( C)
Channel-to-Channel Isolation
vs. Frequency
PSRR vs. Frequency
120
100
80
60
40
20
0
70
60
50
40
30
20
10
0
I
= 1mA
LOAD
R
LOAD
= 100Ω
10
100
1K
10K
100K
1M
100
1K
10K
100K
1M
Frequency (Hz)
Frequency (Hz)
Load Transient Response
Line Transient Response
(I
= 10 to 500mA)
LOAD
T
VOUT
3 >
T
≈
≈
4.5
3.5
T
T
ILOAD
1 >
1) Ch 1: 1 Volt 250 us
500mA
COUT = 100µF
3) Ref B: 50 mVolt 250 us
50µS/Div
Time
Time
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DS9184-00 March 2002
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Preliminary
RT9184
Functional Description
The RT9184 integrate two low noise, low dropout,
and low quiescent current linear regulators. Output
voltages are optional ranging from 1.5V to 3.3V, and
each channel can supply current up to 500mA.
Internal P-Channel Pass Transistor
The RT9184 features double typical 1.3Ω P-channel
MOSFET pass transistors. It provides several
advantages over similar designs using PNP pass
transistors. The P-channel MOSFET requires no
base drive, which reduces quiescent current
significantly than PNP-based regulator, which wastes
considerable current in dropout when the pass
transistor saturates. They also use high base-drive
currents under large loads. The RT9184 does not
suffer from these problems and consume only 185µA
of quiescent current whether in dropout, light-load, or
heavy-load applications.
Current Limit and Thermal Protection
The RT9184 includes two independent current limit
structure which monitor and control each pass
transistor’s gate voltage limiting the guaranteed
maximum output current to 510mA minimum.
Thermal-overload protection limits total power
dissipation in the RT9184. When the junction
temperature exceeds T = +180°C, the thermal
J
sensor signals the shutdown logic turning off the pass
transistor and allowing the IC to cool down. The
thermal sensor will turn the pass transistor on again
after the IC’s junction temperature cools by 20°C,
resulting in a pulsed output during continuous
thermal-overload conditions. Thermal-overloaded
protection is designed to protect the RT9184 in the
event of fault conditions. Do not exceed the absolute
maximum junction-temperature rating of T = +125°C
J
for continuous operation. The output can be shorted
to ground for an indefinite amount of time without
damaging the part by cooperation of current limit and
thermal protection.
DS9184-00 March 2002
www.richtek-ic.com.tw
5
RT9184
Applications Information
Preliminary
two components of the output response: a DC shift
Capacitor Selection and Regulator Stability
Like any low-dropout regulator, the external
capacitors used with the RT9184 must be carefully
selected for regulator stability and performance.
from the output impedance due to the load current
change, and the transient response. The DC shift is
quite small due to the excellent load regulation of the
IC. Typical output voltage transient spike for a step
change in the load current from 0mA to 50mA is tens
mV, depending on the ESR of the output capacitor.
Increasing the output capacitor’s value and
decreasing the ESR attenuates the overshoot.
Using a capacitor whose value is greater than 1µF on
the RT9184 input and the amount of capacitance can
be increased without limit. The input capacitor must
be located a distance of not more than 0.5" from the
input pin of the IC and returned with a clean analog
ground. Any good quality ceramic or tantalum can be
used for this capacitor. The capacitor with larger
value and lower ESR (equivalent series resistance)
provides better PSRR and line-transient response.
Input-Output (Dropout) Voltage
A
regulator’s minimum input-output voltage
differential (or dropout voltage) determines the lowest
usable supply voltage. In battery-powered systems,
this will determine the useful end-of-life battery
voltage. Because the RT9184 uses a P-channel
MOSFET pass transistor, the dropout voltage is a
The RT9184 is designed specifically to work with low
ESR ceramic output capacitor in space-saving and
performance consideration. Using
a
ceramic
function of drain-to-source on-resistance [R
multiplied by the load current.
]
DS(ON)
capacitor whose value is at least 1µF on the RT9184
output ensures the stability. The RT9184 still works
well with output capacitor of other types due to the
wide stable ESR range. Output capacitor of larger
capacitance can reduce noise and improve load-
transient response, stability, and PSRR. The output
capacitor should be located not more than 0.5"
Reverse Current Path
The power transistor used in the RT9184 has an
inherent diode connected between each regulator
input and output (see Fig.1). If the output is forced
above the input by more than a diode-drop, this diode
will become forward biased and current will flow from
from the V
pin of the RT9184 and returned with a
OUT
the V
terminal to V . This diode will also be
OUT
IN
clean analog ground.
turned on by abruptly stepping the input voltage to a
value below the output voltage. To prevent regulator
mis-operation, a Schottky diode could be used in the
applications where input/output voltage conditions
can cause the internal diode to be turned on (see
Fig.2). As shown, the Schottky diode is connected in
parallel with the internal parasitic diode and prevents
it from being turned on by limiting the voltage drop
across it to about 0.3V < 100mA to prevent damaging
the part.
Note that some ceramic dielectrics exhibit large
capacitance and ESR variation with temperature. It
may be necessary to use 2.2µF or more to ensure
stability at temperatures below -10°C in this case.
Also, tantalum capacitors, 2.2µF or more may be
needed to maintain capacitance and ESR in the
stable region for strict application environment.
Tantalum capacitors maybe suffer failure due to
surge current when it is connected to a low-
impedance source of power (like a battery or very
large capacitor). If a tantalum capacitor is used at the
input, it must be guaranteed to have a surge current
rating sufficient for the application by the
manufacture.
V
V
IN
OUT
Load-Transient Considerations
The RT9184 load-transient response graphs show
Fig. 1 V
Structure of RT9184
OUT
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DS9184-00 March 2002
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Preliminary
RT9184
Gold Wire
Die
Polymide Tape
V
V
IN
OUT
Exposed Slug
Leadframe
Fig. 2 External Schottky Diode to Prevent Internal
Diode Turning on
Fig. 3 Power SOP-8 Structure
Power Dissipation and PCB Layout Note
The maximum power dissipation of RT9184 depends
on the thermal resistance from the case to circuit
board, the temperature difference between the die
junction and ambient air, and the rate of airflow. The
power dissipation across the device is
8
1
7
2
6
3
5
4
P = I
(V - V
).
OUT
IN
OUT
The maximum power dissipation is:
PMAX = (T - T ) / θ
Fig. 4 Typical Footprint of RT9184
J
A
JA
where TJ - TA is the temperature difference between
the RT9184 die junction and the ambient
environment, θJA is the thermal resistance from the
junction to the ambient environment. The GND pin of
the RT9184 performs the dual function of providing
an electrical connection to ground and channeling
heat away. Connect the GND pin to ground using a
large pad or ground plane.
The RT9184 is assembled by power SOP-8 package
with direct slug solder to PCB (Fig.3). This structure
offers a low thermal resistance of junction to case
(θJC) and can dissipate the heat away by proper PCB
layout (a proper θCA, thermal resistance of case to
ambient). Because the bottom slug of RT9184 plays
the role as ground, the footprint in Fig.4 is a typical
configuration for heat dissipating copper clad.
Medium power dissipations of up to 2W are easily
obtainable in practice with this configuration. The
heat dissipating copper area on the PCB can be
configured in various shapes and sized depending
upon the particular application.
DS9184-00 March 2002
www.richtek-ic.com.tw
7
RT9184
Package Information
Preliminary
H
A
Y
M
X
B
J
F
C
I
D
Dimensions In Millimeters
Dimensions In Inches
Symbol
Min
Max
Min
Max
A
B
C
D
F
H
I
4.801
3.810
1.470
0.330
1.194
0.190
0.050
5.791
0.380
1.830
1.830
4.950
3.988
1.730
0.508
1.346
0.250
0.150
6.198
1.270
2.290
2.290
0.189
0.150
0.058
0.013
0.047
0.007
0.002
0.228
0.015
0.072
0.072
0.195
0.157
0.068
0.020
0.053
0.009
0.006
0.244
0.050
0.090
0.090
J
M
X
Y
Power 8–Lead SOP Plastic Package
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DS9184-00 March 2002
8
Preliminary
RT9184
DS9184-00 March 2002
www.richtek-ic.com.tw
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RT9184
Preliminary
RICHTEK TECHNOLOGY CORP.
Headquarter
RICHTEK TECHNOLOGY CORP.
Taipei Office (Marketing)
6F, No. 35, Hsintai Road, Chupei City
8F-1, No. 137, Lane 235, Paochiao Road, Hsintien City
Hsinchu, Taiwan, R.O.C.
Taipei County, Taiwan, R.O.C.
Tel: (8863)5510047 Fax: (8863)5537749
Tel: (8862)89191466 Fax: (8862)89191465
Email: marketing@richtek-ic.com.tw
www.richtek-ic.com.tw
DS9184-00 March 2002
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