www.fairchildsemi.com
REV. 1.1.2 4/19/02
Features
• 85% efficiency at 50mA
• 900mV Start-up voltage
• ±2.5% output accuracy
• Only 3 external components required
• 50, 100 and 180kHz versions available
• 0.5µA supply current in shutdown mode
• External transistor option supports up to 1A load currents
Applications
• Cellular Phones, Pagers
• Portable Cameras and Video Recorders
• Palmtops and PDAs
• Battery Powered Systems
Description
The ILC6370 is a compact 50mA boost converter offered in
a 5-lead SOT-89 package. Only three external components
are needed to complete the switcher design, and frequency
options of 50, 100, and 180kHz give the designer the ability
to accommodate a wide range of system objectives, includ-
ing size, electromagnetic interference requirements and so
on. 87% max duty cycle gives conversion efficiencies of
85%.
Standard voltage options of 2.5V, 3.3V, and 5.0V at ±2.5%
accuracy feature on-chip phase compensation and soft-start
design.
The ILC6371 is designed to drive an external transistor for
high current switching regulators applications with all the
features and benefits of the ILC6370 retained.
Block Diagram
VLX LIMITER
PWM Controlled
BUFFER
LX
VSS
EXT
+
-
CHIP ENABLE
OSC
50/100/180KHz
VDD
VOUT
CE
Loop comp
Vref
Slow Start
VDD is internally connected to the VOUT pin.
ILC6370/6371
Super Small Switching Regulator with Shutdown
ILC6370/6371
2
REV. 1.1.2 4/19/02
Pin Assignments
Absolute Maximum Ratings
T
A
= 25˚C, unless otherwise stated
Electrical Characteristics ILC6370BP-50
Unless otherwise specified V
OUT
= V
EN
= 5V, V
IN
= 0.6 x V
OUT
, I
OUT
= 50mA, F
OSC
= 100 kHz, T
A
= 25°C,
Test Circuit Figure 1.
Parameter Symbol Ratings Units
V
OUT
Input Voltage Pin V
OUT
12 V
CE Input Voltage V
CE
12 V
Voltage on pin LX V
LX
12 V
Current on pin LX I
LX
400 mA
Voltage on pin EXT V
EXT
0.3~V
OUT
+ 0.3 V
Current pin EXT I
EXT
±50 mA
Continuous Total Power Dissipation (SOT-89-5) P
D
500 mW
Operating Ambient Temperature T
opr
-40 ~ +85 °C
Storage Temperature T
stg
-40 ~ +125 °C
Parameter Symbol Conditions Min. Typ. Max. Units
Output Voltage V
OUT
4.875 5.0 5.125 V
Input Voltage V
IN
10 V
Oscillation Startup
Voltage
V
ST1
No external components. Apply voltage to
V
OUT
. Lx: 10k
Ω
pull-up to 5V
0.8 V
Operation Startup
Voltage
V
ST2
External components connected.
I
OUT
= 1mA
0.9 V
Supply Current 1 I
DD1
Same as V
ST1
. Apply V
OUT
= 4.75V 80.2 133.8 µA
Supply Current 2 I
DD2
Same as V
ST1
. V
OUT
= 5.5V 8.2 16.5 µA
LX Switch-On
Resistance
R
SWON
Same as I
DD1
. V
LX
= 0.4V 1.4 2.4
Ω
LX Leakage Current I
LXL
No external components. V
OUT
= V
LX
= 10V 1.0 µA
Oscillator Frequency F
OSC
Same as I
DD1
. 85 100 115 kHz
Maximum Duty Ratio MAXDTY Same as I
DD1
. 808792%
Stand-by Current I
STB
Same as I
DD1
. 0.5 µA
CE “High” Voltage V
CEH
Same as I
DD1
. Existence of Lx oscillation 0.75 V
CE “Low” Voltage V
CEL
Same as I
DD1
. Disappearance of Lx
oscillation
0.2 V
CE “High” Current I
CEH
Same as I
DD1
. V
CE
= 4.75V 0.25 µA
CE “Low” Current I
CEL
Same as I
DD1
. V
CE
= 0V -0.25 µA
Efficiency EFF 85 %
Slow Start Time T
SS
4.0 10.0 20.0 mS
SOT-89-5
(TOP VIEW)
132
VOUT CE
LX
45
VSS
N/C
SOT-89-5
(TOP VIEW)
132
VOUT CE
EXT
45
VSS
N/C
ILC6370 ILC6371
ILC6370/6371
REV. 1.1.2 4/19/02
3
Electrical Characteristics ILC6371BP-50
Unless otherwise specified V
OUT
= V
EN
= 5V, V
IN
= 0.6 x V
OUT
, I
OUT
= 50mA, F
OSC
= 100 kHz, T
A
= 25°C,
Test Circuit Figure 2.
Parameter Symbol Conditions Min. Typ. Max. Units
Output Voltage V
OUT
4.875 5.0 5.125 V
Input Voltage V
IN
10 V
Oscillation Startup
Voltage
V
ST1
No external components. Apply voltage to
V
OUT
.
0.8 V
Operation Startup
Voltage
V
ST2
External components connected.
I
OUT
= 1mA
0.9 V
Supply Current 1 I
DD1
Same as V
ST1
. Apply V
OUT
= 4.75V 40.0 66.8 µA
Supply Current 2 I
DD2
Same as V
ST1
. V
OUT
= 5.5V 8.2 16.5 µA
EXT “High” On
Resistance
R
EXTH
Same as I
DD1
. V
EXT
= 0.4V 37.5 62.5
Ω
EXT “Low” On
Resistance
R
EXTL
Same as I
DD1
. V
EXT
= 0.4V 30 50
Ω
Oscillator Frequency F
OSC
Same as I
DD1
. 85 100 115 kHz
Maximum Duty Ratio MAXDTY Same as I
DD1
. 808792%
Stand-by Current ISTB Same as IDD1. 0.5 µA
CE “High” Voltage VCEH Same as IDD1. Existence of Lx oscillation 0.75 V
CE “Low” Voltage VCEL Same as IDD1. Disappearance of Lx
oscillation
0.2 V
CE “High” Current ICEH Same as IDD1. VCE = 4.75V 0.25 µA
CE “Low” Current ICEL Same as IDD1. VCE = 0V -0.25 µA
Efficiency EFF 85 %
Slow Start Time TSS 4.0 10.0 20.0 mS
ILC6370/6371
4REV. 1.1.2 4/19/02
Applications Circuits
Figure 1. Test Circuit
Figure 2. Test Circuit
ILC6370
123
45
CE
VOUT
CL
+
GND
VIN
L
SD
L: 100µH
SD: Schottky diode
CL: 47µF 16V (Ceramic or Tantalum Capacitor)
ILC6371
123
45
CE
VOUT
CL
+
L
SD
VIN
GND
CB
RB
Tr
L: 100µH
SD: Schottky diode
CL: 47µF 16V (Ceramic or Tantalum Capacitor)
RB: 1kΩ
CB: 3300pF
Tr: 2SC3279, 2SDI628G
ILC6370/6371
REV. 1.1.2 4/19/02 5
Functions and Operation
The ILC6370 performs boost DC-DC conversion by control-
ling the switch element shown in the circuit below.
When the switch is closed, energy is built up in the inductor.
When the switch opens, this energy is forced to pass through
the diode to the output. As the on and off cycles continue,
the output capacitor voltage builds up due to energy being
transferred from the inductor
Consequently, the output voltage is boosted with respect to
input. The ILC6370/6371 monitors the voltage on the output
capacitor in order to determine how much energy should be
transferred through the switch.
In general, the switching characteristic is determined by the
desired output voltage and the required load current. Specifi-
cally, the energy transfer is determined by the energy stored
in the coil during each switching cycle.
EL = ƒ(tON, VIN)
where EL is the energy stored in the inductor, tON is the ON
time and VIN is the input voltage.
The ILC6370/6371 use a Pulse Width Modulation (PWM)
technique. The devices are offered with one of three fixed
internal frequencies: 50, 100, or 180kHz. The switches are
continuously driven at these frequencies. The control cir-
cuitry varies the power being delivered to the load by varying
the on-time, or duty cycle, of the switch. Since more on-time
translates to higher energy built up in the inductor, the
maximum duty cycle of the switch determines the maximum
load current that the device can support. The ILC6370 and
ILC6371 both support up to 87% duty cycles, for maximum
usable range of load currents. The internal bias (VOD) is
provided by the output voltage VOUT..
There are two key advantages of PWM type controllers.
First, because the controller automatically varies the duty
cycle of the switch’s on-time in response to changing load
conditions, the PWM controller will always have an
optimized waveform for a steady-state load. This translates
to very good efficiency at high currents and minimal ripple
on the output. [Ripple is due to the output capacitor con-
stantly accepting and storing the charge received from the
inductor, and delivering charge as required by the load. The
“pumping” action of the switch produces a sawtooth-shaped
voltage as seen at the output.]
The other key advantage of the PWM type controllers is that
the radiated noise due to the switching transients will always
occur at a fixed switching frequency. Many applications are
insensitive to switching noise, but certain types of applica-
tions, especially communication equipment, need to mini-
mize the high frequency interference within their system as
much as is possible. Using a boost converter requires a cer-
tain amount of high frequency noise to be generated; using a
PWM converter makes that noise spectrum predictable; thus
it is easier to filter it.
There are downsides of PWM approaches, especially at very
low currents. Since the PWM techniques rely on constant
switching and varying duty cycle to match the load condi-
tions, there is a minimum load current that can be handled
efficiently. If the ILC6370/6371 had an ideal switch, this
would not be such a problem. But an actual switch consumes
some finite amount of current to switch on and off; at very
low current this can be of the same magnitude as the load
current itself, driving switching efficiencies down to 50%
and below.
The other limitation of PWM techniques is that, while the
fundamental switching frequency is easier to filter out since
it’s constant, the higher order harmonics of PWM will be
present and may have to be filtered out as well. Filtering
requirements will vary by application and by actual system
design and layout, so generalization in this area is difficult, at
best. [For other boost converter techniques, please refer to
the ILC6380/81 and ILC6390/91 data sheets.] Nevertheless,
PWM control for boost DC-DC conversion is widely used,
especially in audio-noise sensitive applications or applica-
tions requiring strict filtering of the high frequency compo-
nents. Fairchild’s products give very good efficiencies of
85% at 50mA output (5V operation), 87% maximum duty
cycles for high load conditions, while maintaining very low
shutdown current levels of 0.5µA. The only difference
between the ILC6370 and ILC6371 parts is that the 6371
is configured to drive an external transistor as the switch
element. Since larger transistors can be selected for this
element, higher effective loads can be regulated.
Start-up Mode
The ILC6370 has an internal soft-start mode which
suppresses ringing or overshoot on the output during
start-up. The following diagram illustrates this start-up
condition’s typical performance.
VIN - Vf
VOUT MIN
T SOFT-START (~10msec)
t = 0
ILC6370/6371
6REV. 1.1.2 4/19/02
External Components and Layout
Consideration
The ILC6370 is designed to provide a complete DC-DC
convertor solution with a minimum of external components.
Ideally, only three externals are required: the inductor, a pass
diode, and an output capacitor.
The inductor needs to be of low DC Resistance type,
typically 1Ω value. Toroidal wound inductors have better
field containment (less high frequency noise radiated out)
but tend to be more expensive. Some manufacturers such as
MuRuta and Coilcraft have new bobbin-wound inductors
with shielding included, which may be an ideal fit for these
applications. Contact the manufacturer for more information.
The inductor size needs to be in the range of 47µH to 1mH.
In general, larger inductor sizes deliver less current, so the
load current will determine the inductor size used.
For load currents higher than 10mA, use an inductor from
47µH to 100µH.
For load currents of about 5mA (pagers for example), use of
an inductor in the range of 100µH to 330µH is desirable.
For even lighter loads, an inductor of up to 1mH can be used.
The use of a larger inductor will increase overall conversion
efficiency due to the reduction in switching currents.
For the ILC6371, using an external transistor, the use of a
47µH inductor is recommended based on our experience
with the part. Note that these values are recommended for
both 50kHz and 100kHz operation. If the ILC6370 or
ILC6371 is used at 180kHz switching frequencies, the
inductor size can be reduced to approximately half of these
stated values.
The capacitor should, in general, be ceramic or tantalum
type, as they have much better ESR and temperature stability
than other capacitor types. NEVER use electrolytics or
chemical caps, as the capacitor value changes dramatically
below 0˚C and the overall design may become unstable.
Different capacitor values will directly impact the ripple
voltage seen on the output at a given load current due to the
direct charge-to-voltage relationship of this element. Differ-
ent capacitor values will also indirectly affect system reli-
ability, as the lifetime of the capacitor can be degraded by
constant high current influx and outflux. Running a capacitor
near its maximum rated voltage can deteriorate lifetime as
well; this is especially true for tantalum caps which are par-
ticularly sensitive to overvoltage conditions.
The diode must be of Schottky type for fast recovery and
minimal loss. A diode rated at greater than 200mA and
maximum voltage greater than 30V is recommended for
fast switching time and best reliability over time.
Different diodes may introduce different level of high
frequency switching noise into the output waveform so
trying out several sources may be desirable.
For the ILC6371, much of the component selection is as
described above, with the addition of the external NPN
transistor and the base drive network. The transistor needs to
be of NPN type, and should be rated for currents of 2A or
more. [This translates to lower effective on resistance and,
therefore, higher overall efficiencies.] The base components
should remain at 1kΩ and 3300pF; any changes need to be
verified prior to implementation.
As for actual physical component layout, in general, the
more compact the layout is, the better the overall perfor-
mance will be. It is important to remember that everything in
the circuit depends on a common and solid ground reference.
Ground bounce can directly affect the output regulation and
presents difficult behavior to predict. Keeping all ground
traces wide will eliminate ground bounce problems.
It is also critical that the ground pin of CL and VSS pin of the
device be the same pin on the board, as this capacitor serves
two functions: that of the output load capacitor, and that of
the input supply bypass capacitor.
Layouts for DC-DC converter designs are critical for overall
performance, but following these simple guidelines can
simplify the task by avoiding some of the more common
mistakes made in these cases. Once actual performance is
completed, be sure to double check the design on an actual
manufacturing prototype product to verify that nothing has
changed which can affect the performance.
ILC6370/6371
REV. 1.1.2 4/19/02 7
Typical Performance Characteristics (General conditions for all curves)
OUTPUT CURRENT IOUT (mA)
0
4.4
OUTPUT VOLTAGE VOUT (V)
4.8
100
5.2
200 500
VIN=1.0V
5.0
4.6
4.2
4.0
300 400
L=100µH
C=47µF(Tantalum)
VIN=2.0V VIN=3.0V
VIN=4.0V
5.4
OUTPUT VOLTAGE vs OUTPUT CURRENT
ILC6370CP-50
OUTPUT CURRENT IOUT (mA)
0
2.7
OUTPUT VOLTAGE VOUT (V)
2.9
40
3.1
80 200
3.0
2.8
2.6
120 160
L=100µH
C=47µF(Tantalum)
3.2
OUTPUT VOLTAGE vs OUTPUT CURRENT
ILC6370CP-30
OUTPUT CURRENT IOUT (mA)
0
40
EFFICIENCY: EFFI (%)
80
100 200 500
100
60
20
0
300 400
L=100µH
C=47µF(Tantalum)
VIN=1.0V
VIN=2.0V
VIN=4.0V
VIN=3.0V
EFFICIENCY vs OUTPUT CURRENT
ILC6370CP-50
OUTPUT CURRENT IOUT (mA)
0
40
EFFICIENCY: EFFI (%)
80
40 80 200
100
60
20
0
120 160
L=100µH
C=47µF(Tantalum)
VIN=1.0V VIN=1.5V
VIN=2.0V
EFFICIENCY vs OUTPUT CURRENT
ILC6370CP-30
OUTPUT CURRENT IOUT (mA)
0
40
RIPPLE Vr (mVp-p)
80
100 200
VIN=0.9V
100
60
20
0
300 400
L=100µH
C=47µF(Tantalum) VIN=4.0VVIN=3.0V
RIPPLE VOLTAGE vs OUTPUT CURRENT
ILC6370CP-50
VIN=2.0V
OUTPUT CURRENT IOUT (mA)
0
40
RIPPLE Vr (mVp-p)
80
50 100
VIN=1.0V
100
60
20
0
150 200
L=100µH
C=47µF(Tantalum)
VIN=1.5V VIN=2.0V
RIPPLE VOLTAGE vs OUTPUT CURRENT
ILC6370CP-30
INPUT VOLTAGE VIN (V)
200
INPUT CURRENT (mA)
400
12
500
300
100
0
34
INPUT VOLTAGE vs INPUT CURRENT
ILC6370CP-50, No Load Current
600
L=100µH
C=47µF(Tantalum)
INPUT VOLTAGE VIN (V)
1.0
100
INPUT CURRENT (mA)
200
1.2 1.4 2.0
250
150
50
0
1.6 1.8
L=100µH
INPUT VOLTAGE vs INPUT CURRENT
ILC6370CP-30, No Load Current
C=47µF(Tantalum)
VIN=1.0V
VIN=1.5V VIN=2.0V
ILC6370/6371
8REV. 1.1.2 4/19/02
Typical Performance Characteristics (General conditions for all curves)
TIME (µsec)
-20
4.0
6.0
060
7.0
5.0
3.0
20 40
L=100µH
VIN=3.0V
ILC6370CP-50
OUTPUT VOLTAGE VOUT (V)
TRANSIENT RESPONSE
OUTPUT CURRENT IOUT (mA)
0.4
VST, VHLD (V)
0.8
010
1.0
0.6
0.2
0
20 30
START VOLTAGE/HOLD VOLTAGE vs IOUT
ILC6370CP-50
1.2
VST
VHLD
C=47µF(Tantalum)
80
IOUT=1mA~30mA
ILC6370/6371
REV. 1.1.2 4/19/02 9
Package Dimensions
5-Lead SOT-89
4.5±0.1
1.5±0.1
0.4±0.1
0.
units: mm
4±0.1
1.6±0.2
1.5±0.1 1.5±0.1
±0.1 ±0.1 ±0.1
2.5±0.1
0.42±0.1
∅1.0
54
123
0.4
0.9
MIN.
+0.5
–0.3
4.5
0.42 0.47 0.42
ILC6370/6371
4/19/02 0.0m 001
Stock#DS30006370
2002 Fairchild Semiconductor Corporation
LIFE SUPPORT POLICY
FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES
OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR
CORPORATION. As used herein:
1. Life support devices or systems are devices or systems
which, (a) are intended for surgical implant into the body,
or (b) support or sustain life, and (c) whose failure to
perform when properly used in accordance with
instructions for use provided in the labeling, can be
reasonably expected to result in a significant injury of the
user.
2. A critical component in any component of a life support
device or system whose failure to perform can be
reasonably expected to cause the failure of the life support
device or system, or to affect its safety or effectiveness.
www.fairchildsemi.com
DISCLAIMER
FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO
ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME
ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN;
NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS.
Ordering Information
Part Number Output voltage @ Switching Frequency
ILC6370CP25X 2.5V ± 2.5%@50kHz
ILC6370CP33X 3.3V ± 2.5%@50kHz
ILC6370CP50X 5.0V ± 2.5%@50kHz
ILC6370BP25X 2.5V ± 2.5%@100kHz
ILC6370BP30X 3.0V ± 2.5%@100kHz
ILC6370BP33X 3.3V ± 2.5%@100kHz
ILC6370BP50X 5.0V ± 2.5%@100kHz
ILC6370BP53X 5.3V ± 2.5%@100kHz
ILC6370AP25X 2.5V ± 2.5%@180kHz
ILC6370AP33X 3.3V ± 2.5%@180kHz
ILC6370AP50X 5.0V ± 2.5%@180kHz
ILC6370AP52X 5.2V ± 2.5%@180kHz
ILC6371CP25X 2.5V ± 2.5%@50kHz
ILC6371CP33X 3.3V ± 2.5%@50kHz
ILC6371CP50X 5.0V ± 2.5%@50kHz
ILC6371BP25X 2.5V ± 2.5%@100kHz
ILC6371BP33X 3.3V ± 2.5%@100kHz
ILC6371BP50X 5.0V ± 2.5%@100kHz
ILC6371AP25X 2.5V ± 2.5%@180kHz
ILC6371AP33X 3.3V ± 2.5%@180kHz
ILC6371AP50X 5.0V ± 2.5%@180kHz
Standard product offering comes in tape and reel, quantity 1000 per reel,
orientation right for SOT-89
Product Folder - Fairchild P/N ILC6370AP50 - Product information
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Contents
General description | Features | Applications |
Product status/pricing/packaging
General description
The ILC6370 is a compact 50mA boost
converter offered in a 5-lead SOT-89 package.
Only three external components are needed to
complete the switcher design, and frequency
options of 50, 100, and 180kHz give the
designer the ability to accommodate a wide
range of system objectives, including size,
electromagnetic interference requirements and
so on. 87% max duty cycle gives conversion
efficiencies of 85%.
Standard voltage options of 2.5V, 3.3V, and
5.0V at ±2.5% accuracy feature on-chip phase
compensation and soft-start design.
The ILC6371 is designed to drive an external
transistor for high current switching regulators
applications with all the features and benefits
of the ILC6370 retained.
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Features
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Product Folder - Fairchild P/N ILC6370AP50 - Product information
● 85% efficiency at 50mA
● 900mV start-up voltage
● ±2.5% accurate outputs
● Only 3 external components required
● 50, 100 and 180kHz switching
frequency versions available
● 0.5µA supply current in shutdown mode
● External transistor option supports up to
1A load currents
back to top
Applications
● Cellular Phones, Pagers
● Portable Cameras and Video Recorders
● Palmtops and PDAs
● Battery Powered Systems
back to top
Product status/pricing/packaging
Product Product status Pricing* Leads Packing method
ILC6370AP50X Full Production $1.89 3 TAPE REEL
* 1,000 piece Budgetary Pricing
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