Advanced
Monolithic
Systems
FEATURES
•
Fast Transient Response
•
Dropout Voltage Defined by FET Used
•
Very Tight Load Regulation
•
High Side Sense Current Limit
AMS2115
FAST TRANSIENT RESPONSE LOW DROPOUT REGULATOR
APPLICATIONS
•
Microprocessor Supplies
•
Video Card Supplies
•
Low Voltage Logic Supplies
•
GTL Termination
GENERAL DESCRIPTION
The AMS2115 is a single IC controller that drives an external N channel MOSFET as a source follower to produce a fast
The
transient response, low dropout voltage regulator. The fast transient load performance is obtained by eliminating expensive
tantalum or bulk electrolytic output capacitors in the most demanding modern microprocessor applications. Precision-trimmed
adjustable and fixed output voltage versions accommodate any required microprocessor power supply voltage. By selecting the
N-channel MOSFET RDS(ON) a very low dropout voltage can be achieved. A protection feature includes a high side current
limit amplifier that activates a circuit to limit the FET gate drive. A shutdown pin turns off the gate drive and some internal
circuits to reduce quiescent current. AMS2115 is offered in 8L SOIC and 8L PDIP package.
ORDERING INFORMATION:
PACKAGE TYPE
8L PDIP
AMS2115P
AMS2115P-1.5
AMS2115P-1.8
AMS2115P-2.5
AMS2115P-3.3
AMS2115P-5.0
8L SOIC
AMS2115S
AMS2115S-1.5
AMS2115S-1.8
AMS2115S-2.5
AMS2115S-3.3
AMS2115S-5.0
OPERATING JUNCTION
TEMPERATURE RANGE
-0 to 125° C
-0 to 125° C
-0 to 125° C
-0 to 125° C
-0 to 125° C
-0 to 125° C
S/D
VIN
GND
FB
1
2
3
4
8L SOIC
8L PDIP
8
7
6
5
IPOS
INEG
GATE
COMP
Top View
TYPICAL APPLICATION:
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Advanced Monolithic Systems, Inc.
www.advanced-monolithic.com
Phone (925) 443-0722
Fax (925) 443-0723
AMS2115
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Input Voltage
Operating Junction Temperature Range
ESD
Storage temperature
20V
0°C to 125°C
2000V
- 65°C to +150°C
Soldering information
Lead Temperature (10 sec)
Thermal Resistance
SO-8 package
8L-PDIP package
300°C
ϕ
JA
= 130°C/W
ϕ
JA
= 100°C/W
ELECTRICAL CHARACTERISTICS
Parameter
Supply Current
Reference Voltage
Output Voltage
Output Voltage
Output Voltage
Output Voltage
Output Voltage
Line Regulation
Input Bias Current
OUT Divider Current
Gate Output Swing Low
Gate Output Swing High
IPOS + INEG Supply Current
Current Limit Threshold Voltage
Current Limit Threshold Voltage
Line Regulation
Shut Down Current
(Input Shut Down – High)
Shut Down Input logic
(Shut Down - Low)
Shut Down Input logic
(Shut Down – High)
Shut Down Hysteresis
Output Voltage TC
Reference Voltage TC
(V
OUT
TC)
(V
REF
TC)
(
I
fb)
(Isy)
(V
REF
)
(V
OUT
)
(V
OUT
)
(V
OUT
)
(V
OUT
)
(V
OUT
)
AMS2115
AMS2115-1.5
AMS2115-1.8
AMS2115-2.5
AMS2115-3.3
AMS2115-5.0
AMS2115-XX
AMS2115
AMS2115-XX
AMS2115-XX
AMS2115-XX
AMS2115-XX
AMS2115-XX
AMS2115-XX
AMS2115-XX
AMS2115-XX
AMS2115-XX
AMS2115-XX
AMS2115-XX
AMS2115
T
A
= 25°C, V
IN
= 12V, IPOS = INEG = 5V, SHDN = 0V unless otherwise noted.
Device
Conditions
Min
1.238
1.485
1.782
2.475
3.267
4.950
10 V
≤
V
IN
≤
20V
FB = V
FB
OUT = V
OUT
I
Gate
= 0mA
I
Gate
= 0mA
3V
≤
IPOS
≤
20V
V
IN
- 1.6
0.3
42
37
3V
≤
IPOS
≤
20V
V
Shutdown
= 2.0 V
Low (Regulator On)
High (Regulator Off)
From High To Low
∆T
= TA to 125
°C
∆T
= TA to 125
°C
2.0
Typ
4.5
1.250
1.500
1.0
1.800
2.500
3.300
5.000
0.01
-3.0
0.5
0.1
V
IN
- 1
0.625
50
50
-0.20
5.0
1.2
1.5
150
30
30
Max
7
1.26
1.51
5
1.81
2.52
3.33
5.05
0.3
-4.0
1.0
0.5
Units
mA
V
V
V
V
V
V
V
%/V
µA
mA
V
V
1.0
58
63
-0.50
8.0
1.4
mA
mV
mV
%/V
µA
V
V
mV
ppm/
°C
ppm/
°C
Parameters identified with
boldface type
apply over the full operating temperature range.
Note 1:
Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. For guaranteed specifications and test conditions, see the
Electrical Characteristics
.
The guaranteed specifications apply only for the test conditions listed.
Note 2:
Line regulation is guaranteed up to the maximum input voltage.
Note 3
:
XX represents all output voltages.
Advanced Monolithic Systems, Inc.
www.advanced-monolithic.com
Phone (925) 443-0722
Fax (925) 443-0723
AMS2115
PIN FUNCTIONS
S/D (Pin 1)
This is a shutdown pin that provides GATE drive latchoff
capability. The pin is also the input to a comparator referenced to
V
REF
(1.25V). When the pin pulls above
V
REF
, the comparator
latches the gate drive to the external MOSFET off. The comparator
typically has 150mV of hysteresis and the Shutdown pin can be
pulled low to reset the latchoff function. This pin provides
overvoltage protection or thermal shutdown protection when
driven from various resistor divider schemes. S/D pin is clamped
at 2.5V.
V
IN
(Pin 2)
This is the input supply for the IC that powers the majority of
internal circuitry and provides sufficient gate drive compliance for
the external N-channel MOSFET. The typical supply voltage is 12
with 4.5 mA of quiescent current. The maximum operating
V
IN
is
20V and the MOSFET at max.
I
OUT
+ 1.6V (worst-case
V
IN
to
GATE output swing).
GND (Pin 3)
Analog Ground. This pin is also the negative sense terminal for the
internal 1.25V reference. Connect external feedback divider
networks that terminate to GND and frequency compensation
components that terminate to GND directly to this pin for best
regulation and performance.
FB (Pin 4) Adjustable Version
This is the inverting input of the error amplifier for the adjustable
voltage AMS 2115. The noninverting input is tied to the internal
1.25V reference. Input bias current for this pin is typically – 3
µA
flowing out of the pin. This pin is normally tied to a resistor
divider network to set output voltage. Tie the top of the external
resistor divider directly to the output voltage for best regulation
performance.
OUT (Pin 4) Fixed Output Voltage
This is the input of the error amplifier for the fixed voltage AMS
2115-X. The fixed voltage parts contain a precision resistor
divider network to set output voltage. The typical resistor divider
current is 1 mA into the pin. Tie this pin directly to the output
voltage for best regulation performance.
COMP (Pin 5)
This is the high impedance gain node of the error amplifier and is
used for external frequency compensation. Frequency
compensation is generally performed with a series RC network to
ground.
GATE (Pin 6)
This is the output of the error amplifier that drives N-channel
MOSFETs with up to 5000pf of “effective” gate capacitance. The
typical open-loop output impedance is 2Ω. When using low input
capacitance MOSFETs (,1500pF), a small gate resistor of 2Ω to
10Ω dampens high frequency ringing created by an LC resonance
that is created by the MOSFET gate’s lead inductance and input
capacitance. The GATE pin delivers up to 50mA for a few
hundred nanoseconds when slewing the gate of the N-channel
MOSFET in response to output load current transients.
INEG (Pin 7)
This is the negative sense terminal of the current limit amplifier. A
small sense resistor is connected in series with the drain of the
external MOSFET and is connected between the IPOS and INEG
pins. A 50mV threshold voltage in conjunction with the sense
resistor value sets the current limit level. The current sense resistor
can be low value shut or can be made from a piece of PC board
trace. If the current limit amplifier is not used tie the INEG and
IPOS to power input voltage. This action disables the current limit
amplifier.
IPOS (Pin 8)
This is the positive sense terminal of the current limit amplifier.
Tie this pin directly to the main power input voltage from which
the output voltage is regulated. This pin is also the input to a
comparator that monitors the power input voltage and keeps the
GATE voltage low until power input voltage is at least 1V. This
prevents the external N Channel MOSFET to turn on before V
power is on thus eliminating possible voltage spikes in the output
voltage when powered up.
Advanced Monolithic Systems, Inc.
www.advanced-monolithic.com
Phone (925) 443-0722
Fax (925) 443-0723
AMS2115
PACKAGE DIMENSIONS
inches (millimeters) unless otherwise noted.
8 LEAD SOIC PLASTIC PACKAGE (S)
0.189-0.197*
(4.801-5.004)
8
7
6
5
0.228-0.244
(5.791-6.197)
0.150-0.157**
(3.810-3.988)
1
2
3
4
0.053-0.069
(1.346-1.752)
0.010-0.020 x 45°
(0.254-0.508)
0.004-0.010
(0.101-0.254)
0.008-0.010
(0.203-0.254)
0°-8° TYP
0.014-0.019
(0.355-0.483)
0.050
(1.270)
TYP
0.016-0.050
(0.406-1.270)
S (SO-8 ) AMS DRW# 042293
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
8 LEAD PLASTIC DIP PACKAGE (P)
0.400*
(10.160)
MAX
8
7
6
5
0.255±0.015*
(6.477±0.381)
1
2
3
4
0.045-0.065
(1.143-1.651)
0.130±0.005
(3.302±0.127)
0.300-0.325
(7.620-8.255)
0.065
(1.651)
TYP
0.005
(0.127)
MIN
0.100±0.010
(2.540±0.254)
0.125
(3.175)
MIN
0.018±0.003
(0.457±0.076)
0.009-0.015
(0.229-0.381)
0.015
(0.380)
MIN
0.325 +0.025
-0.015
(
8.255 +0.635
)
-0.381
P (8L PDIP ) AMS DRW# 042294
*DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTUSIONS.
MOLD FLASH OR PROTUSIONS SHALL NOT EXCEED 0.010" (0.254mm)
Advanced Monolithic Systems, Inc.
www.advanced-monolithic.com
Phone (925) 443-0722
Fax (925) 443-0723
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