DEVICE DESCRIPTION
The ZLDO Series low dropout linear regulators
operate with an exceptionally low dropout
voltage, typically only 30mV with a load
current of 100mA. The regulator series features
output voltages in the range 2.70 to 12 volts, this
device provides an output voltage of 2.70 volts.
The ZLDO270 consumes a typical quiescent
current of only 1mA at its maximum rated
output current of 300mA. A battery low flag is
available to indicate potential power fail
situations. If the input voltage falls to within
200mV of the regulated output voltage then the
error output pulls low. The device also features
an active high disable control. Once disabled
the ZLDO quiescent current falls to typically
11
A.
The ZLDO devices are packaged in Zetex SM8
8 pin small outline surface mount package,
ideal for applications where space saving is
important. The device low dropout voltage,
low quiescent current and small size make it
ideal for low power and battery powered
applications. Battery powered circuits can
make particular use of the low battery flag and
shutdown features.
FEATURES
Very low dropout voltage
6mV dropout at 10mA output
30mV dropout at 100mA output
100mV dropout at 300mA output
2.70 volt fixed output
Other voltages available
Low quiescent current
1mA quiescent (typ) at 300mA output
Low battery flag
Shutdown control
Surface mount package
APPLICATIONS
Battery powered devices
Portable instruments
Portable communications
Laptop/Palmtop computers
Electronic organisers
2.70 VOLT ULTRA LOW DROPOUT
REGULATOR
Issue 2 June 1997
ZLDO270
LOW BATTERY
COMPARATOR
Low Battery Flag
Vin
OUTPUT
DRIVE
BIAS
CIRCUIT
SHUTDOWN
THERMAL
SHUTDOWN
Shutdown
Control
BANDGAP
REFERENCE
Vo
Shaping
Gnd
Cs
ABSOLUTE MAXIMUM RATING
Input Supply
Voltage Range
-0.3 to 20V
Shutdown Input
Voltage Range
-0.3 to V
in
Low Battery Output
Voltage Range
-0.3 to 20V
Output Current
300mA
Operating Temperature
-40 to 85C
Storage Temperature
-55 to 150C
Power Dissipation
(T
amb
=25C)
2W (Note 1)
ZLDO270
ELECTRICAL CHARACTERISTICS
TEST CONDITIONS (Unless otherwise stated) T
amb
=25C,I
L
=10mA,C
s
=10pF,C
out
=1
F
Parameter
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Output voltage
V
o
V
in
=3.7V
2.61
2.70
2.80
V
Output voltage
temperature coefficient
V
o
T
V
in
=3.7V
(Note 2, Note 4)
100
2 50
ppm/ C
Line regulation
V
o
V
in
=3.7 to 20V
13
44
mV
Load regulation
V
o
I
L
=10 to 300mA
V
in
=3.7V
35
62
mV
Dropout voltage
(Note3)
V
in
-V
o
I
L
=10mA
I
L
=100mA
I
L
=300mA
6
30
100
10
75
200
mV
Quiescent current
I
q
V
in
=3.7V, I
L
=0
0.55
1
mA
Quiescent current
at shutdown
I
qs
V
in
=3.7V, I
L
=0,
V
shdn
=V
in
11
30
A
Shutdown control input
current
I
ins
V
shdn
=V
in
=3.7V
2
10
A
Shutdown control
threshold voltage
V
ts
V
in
=3.7V
low(on)
high(off)
1.5
0.4
V
Output current in
shutdown mode
(Note4)
I
Ls
V
in
=20V
V
o
=Gnd
50
100
nA
Output noise voltage
(Note4)
e
n
V
in
=3.7V
f=10Hz to 100kHz,
I
L
=100mA
140
V RMS
Low battery detect
voltage
V
in(bld)
V
O
+
0.2
V
O
+ 0.4 V
Low battery flag
output voltage
V
bl
I
bl
=100
A,
V
in
<V
o
+150mV
0.16
0.4
V
Low battery flag
leakage current
I
bl
V
bl
=6V,
V
in
>V
o
+300mV
0.1
1
A
ZLDO270
PIN DEFINITIONS
Pin 1 LBF - Low Battery Flag. An open collector
NPN output which pulls low on failing input
supply.
Pin 2 SC - Shutdown Control. This high
impedance logic compatible input disables the
regulator when taken high. It includes a diode
wired to Vin and so will pass current if taken more
than 0.5V above Vin.
Pin 3 Vin
-
Voltage
Input.
The
power
supply
to
the regulator. The permissible input voltage
range is -0.3 to 20V. An input capacitor is not
mandatory but will be useful in reducing the
coupling of noise from input to output and
minimising the effect of sudden changes in load
current on the input voltage.
Pin 4 N/C - Not Connected. Not internally
connected and so can be left open or wired to any
pin without affecting the performance of the
regulator.
Pin 5 Vout - Voltage Output. The output of the
regulator. An output capacitor of 1uF or greater
and having low ESR should be wired in close
proximity to the regulator to ensure stability for
all loads.
Pin 6 D/C - Do Not Connect. This pin is wired to
an internal circuit node of the regulator. No
external connection should be made to this pin.
Pin 7 Gnd - Ground. The ground connection of
the regulator against which the output voltage is
referenced.
Pin 8 Spg - Shaping. The shaping node for the
error amplifier of the regulator. A capacitor of
10pF wired from this pin to the output pin (pin 5)
gives optimum stability. Improved AC can be
achieved by reducing the value of this capacitor
but stability may be impaired for some load
conditions.
NOTES.
1. Maximum power dissipation of the device is calculated assuming the package is mounted on a PCB
measuring 2 inches square.
2 Output voltage temperature coefficient is calculated as:-
V
O
change x 1000000
V
O
x temperature change
3. Dropout voltage is defined as the input to output voltage differential at which the circuit ceases to
regulate. The value is measured when the output voltage has dropped by 100mV from V
out
measured
at the nominal input V
in
= V
out
+ 1V
4. Guaranteed by design.
FUNCTIONAL DESCRIPTION
The ZLDO is a high performance, ultra low dropout, low quiescent regulator. Available in SM8 surface
mount packaging, the device is able to dissipate 2W(note 1) allowing complete design flexibility with
an input span upto 20V and 300mA output current. The device quiescent is 1mA (typ) at 300mA load
current. A low battery comparator signifies impending battery failure, whilst a shutdown function
reduces quiescent current to a mere 11
A (typ). A precision bandgap reference gives
2.5% output
tolerance and good temperature characteristics over the range -40 to +85C. AC performance is
enhanced via the use of a small external capacitor.
ZLDO270
Output Impedance v Frequency
Frequency (Hz)
10k
100k
0
O
u
t
p
u
t
I
m
p
edan
c
e
(
m
)
200
1000
800
600
400
100
1k
Cout = 1uF
10pF
4.7pF
2.2pF
Ripple Rejection v Frequency
Frequency (Hz)
10k
100k
0
R
i
p
p
le
Re
j
e
c
t
ion
(
d
B
)
5
25
20
15
10
100
1k
30
35
40
45
50
55
2.2pF
4.7pF
10pF
Cout=1F
Output Voltage Temperature Coefficient
Temperature (C)
0
20
60
40
2.690
O
u
t
p
u
t
V
o
l
tag
e (V)
2.695
2.725
2.720
2.715
2.700
-40
-20
80
2.730
Io=10mA
Vin=5v
Quiescent Current v Temperature
Temperature (C)
0
20
60
40
400
Q
u
ie
scen
t
C
u
rren
t
(A)
440
600
560
520
480
-40
-20
80
Vin=5v
Low Battery Flag Operating Point
Temperature (C)
0
20
60
40
2.93
L.B
.
F
.
O
p
erati
o
n
V
o
l
tag
e (V
)
2.94
2.98
2.97
2.96
2.95
-40
-20
80
2.99
3.00
Vin=5v
Io=10mA
Shutdown Current v Temperature
Temperature ( C)
0
20
60
40
6.0
S
h
u
t
d
o
w
n
C
u
rren
t
(
u
A)
14.0
12.0
10.0
8.0
-40
-20
80
16.0
Vin=5v
TYPICAL CHARACTERISTICS
ZLDO270
TYPICAL CHARACTERISTICS
Load Transient Response
Time (s)
80
120
200
160
-0.4
Output V
o
l
tage
Deviati
o
n
(V)
-0.2
0.4
0
0
40
Vin=5v
Io=0mA
Io=100mA
Output Voltage Deviation
Safe Operating Area
Input-Output Differential Voltage (V)
10
20
0.01
L
o
a
d
C
urrent
(A)
0.1
1.0
1
2
5
DC
1s
0.1s
10ms
Line Transient Response
Time (s)
400
600
1000
800
-0.4
Output V
o
l
tage
Deviati
o
n
(
V
)
0
0.8
0.4
0
200
Vin=5v
Vin=10v
Output Voltage Deviation
Io=100mA
Dropout Voltage v Load Current
Load Current (mA)
10
100
0
D
r
o
pout
V
o
ltage (m
V
)
20
100
80
60
40
0.1
1
120
140
160
1000
180
200
85C
25C
-40C
Operation in shaded area not guaranteed
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