ADMOS AMS3121 Current limit protection Datasheet

AMS3121
2A Fast Transient Linear Regulator
General Description
Features
The AMS3121 is a high performance linear regulator
with very low dropout voltage and excellent transient
response. It is designed to operate with wide input
voltage range of 1.5 – 7Volts making it ideal for two
step conversion while maintaining high efficiency for
many power sensitive applications. The device is
capable of supplying 2A of output current with a
typical dropout voltage of 550mV at 2A. The product
is only available in a fixed output voltage option.
The product includes complete short-circuit and
thermal protection. The combination of these two
internal protection circuits gives the device a
comprehensive safety system to safe guard against
extreme adverse operating conditions.
The AMS3121 is available in both 3-pin TO-220 and
TO-263 packages, and it is rated for -40°C to
+125°C temperature range.
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VIN range: 1.5 – 7V
Fixed output voltage as low as 0.6V
2A maximum output current
550mV typical dropout voltage at 2A
Low self noise
125µA typical supply current
PSRR >40dB at 10KHz
Stable with Electrolytic, Tantalum or
Ceramic capacitors
Current Limit protection
Over-Temperature Shutdown
-40 to +125°C temperature range
Available in 3-pin TO-220 and TO-263
surface mount packages
RoHS & WEEE compliant
Applications
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Set-top Box
DVD, Blue-ray DVD writers
LCD TVs and LCD monitors
Battery Powered Equipment
Infotainment
Wireless & RF: applications
High Efficiency “Green” Laptops & notebook
Typical Application
02/11/2010
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AMS3121
2A Fast Transient Linear Regulator
Pin Description (TO-220 and TO-263 3-Pin Package)
Pin #
Symbol
Description
1
VIN
2
GND
Ground
3
VOUT
Output Voltage
Input supply Voltage. It powers the internal control circuitry and the internal power
switch. Bypass VIN with at ceramic capacitor from this pin to ground.
Pin Configuration
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AMS3121
2A Fast Transient Linear Regulator
Absolute Maximum Ratings (1)
Recommended Operating Conditions (2)
Maximum Input Supply Voltage (VIN)………....…...… -0.3V to 15V
Storage Temperature Range……………................ -65⁰C to 150⁰C
Lead Temperature…………………..………….……….…..… 260⁰C
Junction Temperature………...…………………..……..……..125⁰C
Input Voltage………………………….………….……….. 1.5V to 7V
Ambient Operating Temperature…….….………… -40⁰C to 125⁰C
Thermal Information
TO-220 3-pin θJA .. …………...…………….………….…...50⁰C/W
(3)
TO-263 3-pin θJA ………………………….………………30⁰C/W
Electrical Characteristics
Unless otherwise noted: VIN=3.3V; VOUT=1.8V; CIN=10 µF; COUT=22µF; -40⁰C≤TA=TJ≤85⁰C; TJ(Max.)= 125°C; Typical values are TA= 25°C
Parameter
Output Voltage Accuracy
Maximum Output Current
Load Regulation
Line Regulation
Supply Current
Current Limit
Dropout Voltage
Output Noise Voltage
Thermal Shutdown
Thermal Shutdown Hysteresis
Conditions
VOUT
ISUP
ILIM
VDO
en
Min.
Typ.
-3
2
IOUT_Max
ΔVOUT/ΔVIN
PSRR
Notes:
1.
2.
3.
Symbol
Max.
Units
3
%
A
%
%
mA
A
IOUT= 0 – 2A
VIN=3.0 – 7.0V; IOUT=100mA
VIN=3.3V, Io=0A
0.1
0.2
0.2
2.5
IOUT=0.1A; VOUT=95% of VOUT(NOM)
85
IOUT=0.5A; VOUT=95% of VOUT(NOM)
180
IOUT=1A; VOUT=95% of VOUT(NOM)
275
IOUT=2A; VOUT=95% of VOUT(NOM)
550
F=10KHz Io=20mA
40
dB
BW= 100Hz –100 KHz
COUT = 10µF
IOUT = 500mA
125
µV(rms)
145
15
°C
°C
TSD
TSD_HYS
0.5
mV
Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device.
Measured on approximately 1” square of 1 oz. copper.
With package soldering to 0.5in2 copper area over backside ground plane or internal power plane θJA can vary from 20°C/W to >40°C/W depending on
mounting technique. The thermal resistance Junction to Case is 45⁰C/W. Total power dissipation for the switching regulator and the LDO should be taken
in consideration when calculating the output current capability of each regulator
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A
AMS3
3121
2A Fas
st Transien
nt Linear Regulator
Ground Current vs. Output Current
C
VOUT=2.5
5V, VIN=3.3V
70
60
50
40
30
20
10
0
Outp
put Voltage Temperature
T
Variation
Output Voltage (V)
Ground Current ((mA))
Ty
ypical Perfo
ormance Characteris
C
stics (TA = 25°C
2
unless otherwise
o
sp
pecified)
0.0
0.4
0.8
8
1.2
1.6
1.808
1.806
1.804
1.802
1.800
1.798
1.796
1.794
1.792
2.0
0
--25
0
2
25
50
75
5 100
Ambient Temperature
T
(ºC)
-50
0.2
1.0
0.1
0.0
-0.1
0.8
2A
0.6
0.4
0.2
-0.2
1A
0.0
3
4
5
6
Input Voltage (V)
7
Load Regulation
0.2
--25
0
2
25
50
75
5 100
Ambient Temperature
T
e (°C)
-50
125
5
Dro
opout Voltag
ge vs. Outpu
ut Current
0.6
0.5
0.1
Voltage (V)
Output Voltage Change (%)
Dropout Volta
age vs. Temp
perature
Line Regullation VOUT = 2.5V
Voltage (V)
Output
p Voltage
g Error (%)
( )
Output Cu
urrent (A)
125
5
0.0
-0.1
0.4
0.3
0.2
VOUT
= 2.5V
O
0.1
-0.2
0.0
0.0
02/11/2010
0
0.1
1.0
Outputt Current (A)
10.0
0
0
0.5
1
1.5
Output Current
C
(A)
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AMS3121
2A Fast Transient Linear Regulator
Typical Performance Characteristics (TA = 25°C unless otherwise specified)
Load Transient
100mA to 1.5A, VOUT=1.8V,VIN=3.3V, CIN=COUT=22µF
VIN Start-Up
0-550mA, VOUT=1.8V,VIN=3.3V, CIN=COUT=22µF
V OUT
50mVac
/div
V OUT
1V /div
ISW OUT
500mA
/div
VIN
1V/div
10 µsec/div
02/11/2010
100 µsec/div
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AMS3121
2A Fast Transient Linear Regulator
Functional Block Diagram
VIN
VOUT
Current Limit
Enable
R1
-
Error
Amp
+
R2
Over Temperature
VREF= 0.6V
GND
Figure 1: Block Diagram of AMS 3121 3-Pin TO-220 (T) / TO-263 (M)
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AMS3121
2A Fast Transient Linear Regulator
Device Summary
The AMS3121 is a high voltage low drop out linear
regulator with a current capability of up to 2A. The
LDO has an input voltage range of 1.5V to 7V with an
output voltage as low as 0.6V and is stable with a
wide range of ceramic, tantalum, and electrolytic
output capacitors.
Fault Protection
Short circuit and over-temperature shutdown disable
the converter and LDO in the event of an overload
condition. Overtemp shutdown disables the device
when the junction temperature exceeds 145 ºC. The
output current is internally limited to 2.5A.
Input Capacitor
An input bypass capacitor ranging from 1µF to 10µF
is required. The capacitor should be placed as close
as possible to the device and not be placed more than
1 inch from the LDO.
Output Capacitor
The output capacitor requirements range from the
minimum value required to guarantee stability to
larger values required to meet the extreme transient
response requirements. Values range from 10 to
22µF X5R ceramic capacitors. Due to the extreme
voltage coefficient of X5R ceramic capacitors, the
voltage rating should be at least double the maximum
applied voltage.
02/11/2010
PCB Layout
The following guidelines should be followed to insure
proper layout.
1. VIN Capacitor. A low ESR ceramic bypass
capacitor must be placed as close to the IC as
possible.
2. Ground.
3. For good thermal performance vias are required
to couple the exposed tab of both TO-220 and
TO-263 packages to the PCB ground plane. The
via diameter should be 0.3mm to 0.33mm
positioned on a 1.2mm grid.
Output Power and Thermal Limits
The AMS3121 junction temperature and current
capability depends on the internal dissipation and the
junction to case thermal resistance of the TO-220 and
TO-263 exposed tab packages. Additionally, the tab
paddle and PCB temperature will be elevated due to
the total losses of the LDO and of other circuits
mounted to the PCB.
Tjmax=Pd·θjc+Tpcb+Tamb
The internal losses contribute to the junction
temperature rise above the paddle and PCB
temperature.
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AMS3121
2A Fast Transient Linear Regulator
Figure 2: AMS3121 TO-263 3-Pin Option
Evaluation Board - Top Side
Figure 3: AMS3121 TO-263 3-Pin Option
Evaluation Board - Bottom Side
C3
470uF *1
C4
22uF *2
GND
VOUT
3
Vin
2
1
VIN
U1
AMS3121
C1
22uF
Vout
C2
22uF
C6
22uF *2
C5
470uF *1
gnd
gnd
C1, C2 22uF X5R 1210 10V Ceramic Capaci tor
*1. Optional Electrolyti c Capaci tor in place of Ceramic Capacitor
*2. Optional Tantalum Capacitor in place of Ceramic Capacitor
Figure 4: AMS3121 Evaluation Board Schematic
Table 1: Evaluation Board Bill of Materials
Manufacturer Manufacturer Part Number
Component
Value
C1,C2
C3,C5,C4,C6
U1
22µF, 10V, X5R, 0805, Ceramic
Optional
Low Drop Out Linear Regulator
02/11/2010
Taiyo Yuden
LMK212BJ226MG-T
AMS
AMS3131
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AMS3121
2A Fast Transient Linear Regulator
Ordering Information
Device
AMS3121T-XX(1)(2)(3)
TO-220 3-Pin
Package
AMS3121M-XX(1)(2)(3)
TO-263 3-Pin
Notes:
1. Available in tape and reel only. A reel contains 2,500 devices.
2. Available in lead-free package only. Device is fully WEEE and RoHS compliant
3. Need to specify output voltage option ( )
Outline Drawing and Landing Pattern
Package dimensions are inches (millimeters) unless otherwise noted.
0.060
(1.524)
TYP
0.390-0.415
(9.906 -10.541 )
0.165-0.180
(4.191-4.572)
0.004 +0.008
-0.004
( 0.102 +0.203
-0.102
0.330 -0.370
(8.382-9.398 )
0.199 -0.218
(5.05-5.54)
0.090-0.110
(2.286 -2.794)
02/11/2010
0.032
(0.81)
TYP
0.045-0.055
(1.143-1.397)
0.108
(2.74)
TYP
0.013-0.023
(0.330 -0.584)
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)
0.095-0.115
(2.413-2.921)
0.90-0.110
(2.29-2.79)
M (DD3) AMS DRW #
042191R1
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