®
L4955
5A ULDO LINEAR REGULATORS FAMILY
UP TO 5A OUTPUT CURRENT
±
2% PRECISE OUTPUT VOLTAGES
FAST TRANSIENT RESPONSE
0.75V TYP. DROP OUT VOLTAGE AT 5A
OPERATING INPUT VOLTAGE FROM 4.5V
ADJUSTABLE VERSION:
•
V
O
= 1.26V
•
INHIBIT (I
Q
= 120µA TYP.)
•
POWER GOOD
•
PROGRAMMABLE CURRENT LIMIT
•
HEPTAWATT PACKAGE
FIXED VERSION:
•
3.3V, 5.1V OUTPUTS
•
VERSAWATT PACKAGE
VERY LOW QUIESCENT CURRENT
SHORT CIRCUIT PROTECTION (Foldback
function)
THERMAL SHUTDOWN
APPLICATIONS
PENTIUM
™
AND POWER PC
™
SUPPLIES
POST REGULATOR FOR SMPS
LOW COST SOLUTION FOR 5V TO 3.3V
CONVERSION
LOW COST BATTERY CHARGER
CONSTANT CURRENT REGULATOR
SUITABLE
FOR
APPLICATION WITH
STANDBY FEATURE
DESCRIPTION
The L4955 is a family of monolithic ultra very low
drop linear regulators designed to supply the
most recent microprocessors.
TYPICAL APPLICATIONS
INH
V
IN
IN
1
3
PG
6
7
OUT
R1
5
GND
ADJ
R2
C2
V
OUT
MULTIPOWER BCD TECHNOLOGY
HEPTAWATT
ORDERING
NUMBERS
L4955
L4955V3.3
L4955V5.1
OUTPUT
VOLTAGE
1.26V ADJ
3.3V
5.1V
VERSAWATT
(TO-220)
PACKAGE
HEPTAWATT
VERSAWATT
VERSAWATT
The dropout voltage is only 0.75V (Typ.) at 5A, di-
rectly dependent on the output current conditions.
Realized in BCDII technology, it has on board a
charge pump to properly drive an N-channel
power mos Transistor with 150m
Ω
of R
DSON
.
It operates from a 4.5V minimum supply, with a
very low quiescent current irrespective of the
load; a minimum of 22µF output capacitor is re-
quired for stability.
The on-chip trimming techniques improve the pre-
cision of the available output voltages to
±
2%.
Ancillary functions like power good, inhibit with
low power consumption, programmable output
voltage and current limiting make the flexible
heptawatt version usable in applications where
power management, stand-by, features, post
regulation and adjustable current generators for
battery chargers are important.
L4955
C1
CL
2
4
V
IN
C1
IN
1
L4955VXXX
2
GND
3
OUT
V
OUT
C2
D97IN590
D97IN589
February 1999
1/14
L4955
ABSOLUTE MAXIMUM RATINGS
Symbol
V
IN
Supply Input Voltage
ADJ and CL pins
PG and INH pins
P
TOT
T
st
, T
i
Power Dissipation @ T
amb
= 50°C
Power Dissipation @ T
case
= 90°C
Storage Temperature
Parameter
Value
24
-0.3 to 4
0 to V
IN
2
15
-40 to +150
Unit
V
V
V
W
W
°C
PIN CONNECTIONS
(Top views)
7
6
5
4
3
2
1
tab connected to pin 4
D96IN367
OUT
PG
ADJ
GND
INH
CL
IN
D96IN369
3
OUT
GND
1
IN
HEPTAWATT
VERSAWATT
(TO220)
BLOCK DIAGRAM
V
IN
10µF
IN
1(1)
V
REF
=
1.26V
FIXED
C.L.
CHARGE
PUMP
FOLDBACK
PRE
REGULATOR
+
-
E/A
PROGRAM.
C.L.
BUFFER
POWER
DMOS
150mΩ
OUT
7(3)
R1
ADJ
V
OUT
22µF
THERMAL
SHUTDOWN
INH
3
V
REF
+
2
PIN x = HEPTAWATT
PIN (x) = VERSAWATT
R
CL
(1/4W, 1%)
CL
4(2)
GND
-
0.9V
REF
6
PG
D96IN366
1.26V
INHIBIT
ACTIVE HIGH
5
+
-
R2
2/14
L4955
PIN FUNCTIONS
HW
1
2
3
4
5
6
7
VW
1
–
–
2
–
–
3
Name
IN
CL
INH
GND
ADJ
PG
OUT
Function
Unregulated input voltage; this pin must be bypassed with a capacitor larger than 10
µ
F.
A resistor connected between this pin and ground sets the programmable current limiting
value. When the programmable current limiting is not used the pin must be connected to GND.
TTL-CMOS input. A logic high level on this input disables the device. An internal pull-down
insures full functionally even if the pin is open.
Ground.
The output is connected directly to this terminal for 1.26V operation; it is connected to the
output through a resistive divider for higher voltages.
Open drain output, this signal is low when the output voltage is lower than 90%, otherwise is high.
Regulated output voltage. A minimum bypass capacitor of 22
µ
F is required to insure stability.
THERMAL DATA
(HEPTAWATT & VERSAWATT packages)
Symbol
R
th j-case
R
th j-amb
Parameter
Thermal Resistance Junction-case
Thermal Resistance Junction-ambient
Thermal Shutdown
Thermal Hysteresis
Max.
Max.
Typ.
Typ.
Value
2.5
50
150
20
Unit
°C/W
°C/W
°C
°C
L4955 - ELECTRICAL CHARACTERISTICS
(T
j
= 25°C, V
in
= 12V, unless otherwise specified).
•
= Specifications referred to T
J
from 0°C to +125°C.
Symbol
V
IN
V
O
∆
V
O
∆V
O
V
O
Parameter
Operating Supply Voltage
Output Voltage (1)
Line regulation
Dropout Voltage
(1)
0.1A < I
O
< 5A; 4.5V < V
IN
<12V
4.5V < V
IN
< 12V; 0.1A < I
O
< 5A
4.5V < V
IN
<22V; I
O
= 10mA
0.1A < IO < 5A
I
O
= 5A
V
IN
≥
4.5V
I
O
= 2A
I
O
Current Limiting
Short Circuit Current
Programmable Current
Limiting
I
Q
Quiescent Current
Stand By Current
Inhibit Threshold
Inhibit Hysteresis
Inhibit Bias Sink Current
Power Good Threshold
Power Good Hysteresis
Power Good Saturation
Ripple Rejection
(1) Output voltage connected to ADJ.
Test Condition
Min.
4.5
1.235
1.222
Typ.
1.26
1.26
2
2
0.75
1.1
0.55
Max.
22
1.285
1.298
10
10
1.1
1.5
0.75
7.5
3.45
1.00
3
4
200
1.42
60
Unit
V
V
V
mV
mV
V
V
V
A
A
A
A
mA
mA
µ
A
V
V
µ
A
V
V
•
Load regulation (1)
V
O
= 0V
R
lim
= 13kΩ
R
lim
= 47k
Ω
0.1A < I
O
< 5A
INH = 5V
Rising Edge
INH = 5V or 0.8V
Rising Edge
I
PG
= 4mA
f = 120Hz, I
O
= 5A
V
IN
= 6V
∆
V
IN
= 2V
PP
C
L
= 0
C
L
= 13k
•
•
•
•
•
•
5.1
2.55
0.70
6.3
1.8
3
0.85
2
2.7
•
120
1.1
1.26
0.2
20
0.9 x V
O
0.2
0.1
60
75
•
•
0.4
V
dB
3/14
L4955
L4955V3.3 - ELECTRICAL CHARACTERISTICS
(T
j
= 25°C, V
in
= 5V, unless otherwise specified)
•
= Specifications referred to T
J
from 0°C to +125°C.
Symbol
V
IN
V
O
Parameter
Operating Input Voltage
Output Voltage
4.75V < V
IN
< 12V; 0.1A < I
O
< 5A
4.75V < V
IN
< 12V; 0.1A < I
O
< 5A
∆
V
O
∆V
O
I
O
Line regulation
Load regulation
Current Limiting
Short Circuit Current
I
Q
Quiescent Current
Ripple Rejection
V
O
= 0V
0.1A < I
O
< 5A
f = 120Hz, I
O
= 5A
V
IN
= 6V
∆
V
IN
= 2V
PP
57
4.5V < V
IN
<12V; I
O
= 10mA
0.1A < IO < 5A
Test Condition
Min.
4.5
3.234
3.300
3.300
2
3
Typ.
Max.
22
3.366
3.399
10
15
7.5
Unit
V
V
V
mV
mV
A
A
3
mA
dB
•
3.201
•
•
5.1
6.3
1.8
2
70
L4955V5.1 - ELECTRICAL CHARACTERISTICS
(T
j
= 25°C, V
in
= 8V, unless otherwise specified)
•
= Specifications referred to T
J
from 0°C to +125°C.
Symbol
V
IN
V
O
Parameter
Operating Input Voltage
Output Voltage
6.75V < V
IN
< 15V; 0.1A < I
O
< 5A
6.75V < V
IN
< 15V; 0.1A < I
O
< 5A
V
D
Drop-out Voltage
I
O
= 5A
Test Condition
Min.
V
O
+V
D
5.000
5.100
5.100
0.75
Typ.
Max.
22
5.200
5.250
1.1
1.5
0.75
10
20
7.5
Unit
V
V
V
V
V
V
mV
mV
A
A
3
mA
dB
•
•
•
4.950
1.1
0.55
2
5
I
O
= 2A
∆V
O
∆V
O
I
O
Line regulation
Load regulation
Current Limiting
Short Circuit Current
I
Q
Quiescent Current
Ripple Rejection
V
O
= 0V
0.1A < I
O
< 5A
f = 120Hz, I
O
= 5A
V
IN
= 8V
∆
V
IN
= 2V
PP
6.5V < V
IN
<15V; I
O
= 10mA
0.1A < IO < 5A
•
•
5.1
6.3
1.8
2
55
65
4/14
L4955
L4955
Figure 1:
L4955 DC Operating Area
O u tput C ur rent [A ]
8
7
6
5
4
3
2
1
0
0
2.5
5
D C O perating A re a
T c = 70°C
P dm ax = 22W
7.5
10 12.5 15
(V in - Vou t) [V ]
17.5
20
22.5
R dson
lim it
Pow er D is sipation Lim it
T c = 25°C
P dm ax = 40W
C urr ent Lim itation
V in > 4.5V
T j = 125°C
Figure 2:
Output Voltage Stability vs. Junction
Temperature
Vo u t [V ]
1 .2 8
1 .2 7 5
1 .2 7
1 .2 6 5
1 .2 6
1 .2 5 5
1 .2 5
1 .2 4 5
1 .2 4
-40
V in = 1 2 V
Io u t= 1 0 m A
0
40
T j [°C ]
80
1 20
160
Figure 3:
Line Regulation vs. Junction
Temperature
[m V
5
4 .5
4
3 .5
3
2 .5
2
1 .5
1
0 .5
4 .5V < V in< 2 2V
Iou t= 1 0 m A
Figure 4:
Load Regulation
5
[m V ]
4
3
2
1
0
-1
-2
-3
-4
Vo u t = V
A D J
V in = 1 2 V
T j = 25
°
C
( P u ls e d t e c h n iq u e h a s b e e n u s e d )
Deviation
Voltage
Output
0
O utput Voltage
D eviation
-4 0 -2 0
0
20 40 60 80 100 120 140 160
T j [°C ]
-5
0
1
2
Io u t [A ]
3
4
5
Figure 5:
Dropout Voltage
M in im u m V in - Vo u t Vo lta g e [V ]
1 .2 5
Figure 6:
Maximum OutputCurrent vs. Junction
Temperaturewith internalcurrent limiting
O utput C urrent [A]
10
9
T j = 1 2 5
°
C
1
8
7
0 .7 5
T j = 2 5
°
C
6
5
4
T j = -4 0
°
C
0 .5
3
2
(Vin-Vout) > 2V
pin 2 = G ND
0 .2 5
P u l s e d t e c h n iq u e h a s b e e n u s e d
1
6
0
0
1
2
3
Io u t [A ]
4
5
0
-40 -20
0
20
40
60 80 100 120 140 160
Tj [°C]
*P ulsed tecnique ha s been used
5/14
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