LSP6501
1.6A, 1.3MHz, Boost DC-DC Converter
With Internal Switch
GENERAL DESCRIPTION
The LSP6501 is a current mode step up
converter that can carry out 1.6A. LSP6501 also
builds up a internal switch with 0.23Ω to provide a
high efficient regulator with fast response. The
LSP6501 can be operated at 640KHz or 1.3MHz
allowing for small filter solution and low noise. An
external compensation pin gives the user
flexibility in setting up loop compensation, which
allows to use a low- ESR ceramic output
capacitors. Internal Soft-start function results in
small inrush current and the sofe-start can be
programmed with an external capacitor.
The LSP6501 device includes under-voltage
lockout, and current limiting protection preventing
damage in the event of an output overload. A low
profile 8-pin MSOP packages is available in the
LSP6501.
FEATURES
1. 1.6A, 0.23Ω, Internal Switch
2. Input Range: +2.6V to +5.5V
3. Low Shutdown Current: 0.1uA
4. Adjustable Frequency: 640kHz or 1.3MHz
5. Small 8-Pin MSOP Package
TYPICAL APPLICATIONS
TFT-LCD Power Management
Portable DVD Player Power Management
PIN ASSIGNMENT
VER. 1.2
1/10
1
2
3
4
8
7
6
5
FB
VDD
FREQ
SS
SW
SHDN
COMP
MSOP-8
(Top View)
GND
PIN DESCRIPTION
Pin Name Function
1 COMP Compensation Pin for Error Amplifier
2 FB
Feedback Pin with a Typical Reference Voltage of 1.24V, VOUT = 1.24×(1+ R1/R2).
3 SHDN Shutdown Control Pin. When SHDN is Low, the LSP6501 Will Turn Off
4 GND Ground
5 SW Switch Pin
6 VDD Power Supply Pin
7 FREQ
Frequency Select Pin. Oscillator Frequency to 640kHz When FREQ is Low, and
1.3MHz When FREQ is High
8 SS Soft-Start Control Pin.
LSP6501
1.6A, 1.3MHz, Boost DC-DC Converter
With Internal Switch
TYPICAL APPLICATION CIRCUIT
BSOLUTE MAXIMUM RATINGS
A304
VCC
SS GND
FB
DF
L
SW
FREQ
COMP
RP
CP2
2.6 ~ 5.5VDC COUT
CIN
CP1
R1
R2
VIN VOUT
CSS
C3
R3
LSP6501
A
Value Unit
Parameters
VER. 1.2
2/10
SW to GND 18 V
Input Voltage: SHDN / VDD / FREQ to GND 6 V
SS to GND -0.3 ~ + 0.3 VDD V
SW pin maximum current 2.3 A
Operating temperature -20 ~ +85 °C
Maximum Operating Junction Temperature, TJ150°°C
Storage Temperature Range -45 to 125 °C
Lead Temperature (Soldering, 10 seconds) 260 °C
Note: Exceeding these ratings could cause d
Currents are positive into, negative o
amage to the device. All volt respect to Ground.
ut of the specified terminal.
a re with ges a
HERMAL IMPEDIENCE
T
Thermal Resistance from Junction to Ambient, θ JA 152°C /W
LECTRICAL CHARACTERISTICS
E
DD A
Min Typ Max Unit
(V =SHDN
__________
=3V, FREQ=GND; T =25°C, unless otherwise noted)
Parameter Symbol Conditions
Inpu nge t Voltage Ra VDD 2.6 5.5 V
VDD UVLO
When VDD is rising, typical hysteresis
; SW remains of 2.25 2.38 2.52
Under voltage Lockout is 40mV f below this
level
V
Quiescent Current IDD
FB
VFB=1.0V, switching 1.2 5.0
mA
mA
V=1.3V, Not switching 0.21 0.35
LSP6501
1.6A, 1.3MHz, Boost DC-DC Converter
With Internal Switch
VER. 1.2
3/10
Shutdown Current ISC SHDN
__________ = GND 0.1 10 uA
FB Reference Voltage VFB 1.228 1.252 1.24 V
FB Input Current Ibias VFB=VREF 1 40 nA
FB Voltage Line
Regulation COMP=FB, 2.6V＜VDD＜5.5V - 0.1 0.15 %/V
Error Amp
ansconductanceTr * Gm 7
ICOMP=±5uA 0 105 240
uA/
V
Err n* or Amp Gai AV - 1500 - V/V
FREQ=GND 540 640 740
Oscillated Frequency Fosc FREQ=V 1100 16
DD 1320 00 kHz
FREQ=GND 79 85 92
Maximum Duty Cycle DMAX FREQ=VDD 85
%
Current Limit ILIM V
DD=1V, D=0.65 1.2 1.6 2.3 A
ON-Resistance RON 0.23 0.5
Ω
Isw=1.2A
Leakage Current ISWOFF V=12V
SW 0.01 20 uA
Res nce et Switch Resista 300 Ω
Sof nt 1.5 t Start Charge curre Iss Vss=1.2V 4 7 uA
Input Low Voltage V SHDN
__________ , FREQ; V . 0
IL DD=2.6V to 5.5V .3VDD V
Input High Voltage VIH SHDN
__________ , FREQ; VDD . 0DD
=2.6V to 5.5V .7V V
Hysteresis SHDN
__________ , FREQ; 0.1 DD
V V
FREQ Pull-Down Current I 5.0 9.0
FREQ 1.8 uA
SHDN Input Current Ishut ndow 0.001 1 uA
*: Guaranteed by design, not 100% tested in production.
FUNCTIONAL BLOCK DIAGRAM
1
Driver
FB
Ramp
Summe
r
PWM
Comparator
Error
A
mp
63mΩ
Sync S
LOGIC
CONTROL
R
∑
Switch
Oscillator
＋
－ －
＋
1.24V
Reference
2
7
3
6
4
8
5
GND
SHDN
VDD
SW
SS
COMP
FREQ
Current
Sense
Slope
Compensation
LSP6501
1.6A, 1.3MHz, Boost DC-DC Converter
With Internal Switch
TYPICAL CHARACTERISTICS
Unless otherwise specified, TA = 25°C.
Efficiency vs. Output Curre nt
40%
50%
60%
70%
80%
90%
100%
0 40 80 120 160 200
Output Current (mA)
Efficiency
Fose=1.2MHZ
L=4.7uH
VIN =2.7V
VIN =3.3V
VIN =5V
Efficiency vs. Output Curre nt
100%
40%
50%
60%
70%
80%
90%
0 40 80 120 160 200
Output Current (mA)
Efficiency
Fose= 640KHZ
L=4.7uH
VIN =2.7V
VIN =3.3V
VIN =5V
VER. 1.2
4/10
Output Voltage vs. Load Current
7.0
8.0
9.0
10.0
0 40 80 120 160 200
Load Current (mA)
Output Voltage (V)
Fosc=640KHZ
VIN= 3.3V
Output Voltage vs. Load Current
7.0
8.0
9.0
10.0
0 40 80 120 160 200
Load Current (mA)
Output Voltage (V)
Fosc=1.2MHZ
VIN=3.3V
Current Lim it vs. Duty Cycle
1.4
1.6
1.8
2.0
2.2
2.4
20% 40% 60% 80%
Duty (%)
Limit Current (A)
L=4.7uH
640KHZ
1.2MHZ
Max Load Current vs. Input Voltage
350
460
570
680
790
900
2.5 3.0 3.5 4.0 4.5 5.0
Input Voltage (V)
Output Current (mA)
VIN=3.3V
L=4.7uH
640KHZ
1.2MHZ
LSP6501
1.6A, 1.3MHz, Boost DC-DC Converter
With Internal Switch
FUNCTION DESCRIPTION
Package
A304
VCC
SS
FB
GND
DF
L
SW
FREQ
COMP
RP
CP2
2.6 ~ 5.5VDC COUT
CIN
CP1
R1
R2
VOUT
CSS
C3
R3
LSP6501
VIN
C.R NO Q’TY Value Description
IC 1 - LSP6501 MSOP-8
D- Schottky Diode 40V/2A SMA
F1
C10uF / 10V CAP C SM
VER. 1.2
5/10
IN 1 ER SMD D 1206
COUT uF / 25V SMD 2 10 CAP CER SMD 1206
L 1 4.7uH 1.0A NR4018-100M SMD
R11 *NOTE 1 Chip Resistor / 1% SMD 0603
R21 12K Chip Resistor / 1% SMD 0603
RP1 10K Chip Resistor / 1% SMD 0603
(R3) *NOTE 2 onal) 1 (Opti Chip Resistor / 1% SMD 0603
(C3) *NOTE 2 nal) 1 (Optio CAP CER X7R SMD 0603
(CP1) nal) 1 (Optio CAP CER X7R SMD 0603
CP2 1 10nF CAP CER X7R SMD 0603
CSS 1 1uF CAP CER X7R SMD 0603
*NOTE FB(1+R1/R2)
*NOTE 2: R3 & C3 & CP1 d proving th ance. Beca onents are
not ideal, some es the system needs R get better e value is
cording to real load conditions.
1. Setting the O
FB pin LSP6501. By using the resistor divider, R1 and R2, to
feedback signal, the output voltage is determined by:
1: VOUT=V
are use for im e transient perform use the comp
tim 3 & C3 & CP1 to transient. Th
determined ac
utput Voltage
is used to set the output voltage VOUT of the
divide VOUT to the FB pin as
21
2RR R
VV OUTFB +
⋅=
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛+⋅=
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛+⋅=
2
1
2
1124.11 R
R
V
R
R
VV FBOUT
Where, the feedback pin voltage, VFB, is fixed at 1.24V.
2. Selection of Output Capacitor
the capacitance is high enough and the ESR (Effective
se (high capacitance & low ESR) are very important for the Boost
VOUT ripple and load transient specifications.
It is recommended to select output capacitors that
Series Resistance) is low enough. The
Converter to be able to meet the
Ceramic capacitors often have low ESR and can meet the Boost Converter requirements as long as the
capacitance values are enough. Note that the capacitance values of all kinds of ceramic capacitor drop when
LSP6501
1.6A, 1.3MHz, Boost DC-DC Converter
With Internal Switch
VER. 1.2
6/10
there are DC voltages bias on them. The higher the DC bias, the lower the effective capacitance. The Zxx
serie
itors are similar.
s capacitors (ex: Z5U) often drop more capacitance than what Yxx series capacitors (ex: Y5V) will drop.
And Yxx series are usually worse than Xxx series (ex: X5R). Therefore, it is better to use X5R/X7R type of
ceramic capacitors and don’t use Yxx series (ex: Y5V) or Zxx series (ex: Z5U) types of capacitor. Although
they could be cheaper than X5R or X7R, Yxx series and Zxx series’ permanence is not as good as X5R/X7R
and is easier to have problems like audio noise problem.
The lifetime of a ceramic capacitor is shorter if the DC-bias is close to its maximum DC rating. For
example, to a VOUT=12V application, a 25VDC capacitor should have a longer lifetime than a 16VDC capacitor
does, even when other characteristics of these two capac
Electrolytic capacitors have higher ESR than what ceramic capacitors do. If electrolytic capacitors are
used as output capacitors, the ESR should be low enough to meet the VOUT ripple voltage requirement:
RippleI
ESR
OUT
OUT
<<
For example, if the V ripple voltage of a 5V output DC/DC converter should be smaller tha
VoltagePeaktoPeakRippleV )(
OUT n
250mVPeak-to-Peak and if the ripple current is 0.5A, an c pacitor whose ESR is << (0.25V/0.5A)≒500mΩ should
be chosen. A 680uF of ESR<500 mΩ capacitor can be used in this case.
citors or other capacitors that the
ESR
high, the ripple current
coul
3. S
t capacitor of the Boost
Converter. The capacitor(s) is better to be X7R/X5R type.
uency is larger than 300KHz, although the cost of
ould be cheaper. The DC-R of the chock wire should be as low as possible to reduce the
pow
a
Note that the ESR of electrolytic capacitor is highly dependent on the temperature - the lower the
temperature the higher the ESR and vice versa. This temperature dependence causes VOUT ripple problem
and system stability problem sometimes. It may need to use tantalum capa
are temperature independent for applications that temperature ranges are wide.
It is important to ensure the ripple current rating of the output capacitor is enough or the capacitor might
burn out during operation. To most electrolytic capacitors, the body temperatures should not be higher than
environment temperature plus 10°C. If the body temperature of the capacitor is too
d be higher than the rating of the capacitor. For example, if the air temperature that close to the input
capacitor is 45°C, it is better that the body temperature is << (45°C + 10°C ) = 55°C.
election of Input Capacitor
It is recommended to put a ceramic capacitor(s) of several uF to 10uF as inpu
4. Selection of Inductor
It is recommended to use ferrite core as the chock material. Don’t use iron powder core because the core
loss will be too high for applications that the operation freq
an iron powder core c
er loss.
Below is an equation about the inductor value:
)3()()(
,⋅SWMAXOUTOUT fIV ,
2
,
η
⋅⋅⋅ MININOUTMININ
Where,
VVoltageInputMinimumV
HValueInductorL
SW
MAXOUT
MIN
:
)(:
)(:
)(:
)(:
)( :
,
η
Using a higher value inductor can reduce the power loss of the Boost converter. Anyway, a higher value
inductor often is bigger in size or has higher DC-R, and the higher DC-R may increase the inductor power loss.
Shielding inductor has better EMI performance but the DC-R is often higher than non-shielding inductors of
the s
−
=VVV
L
EfficiencyTypical
HzFrequencySwitchingf
ACurrentOutputMaximumI
VVoltageOutputTypicalVOUT
IN,
ame size.
It is recommended to adopt an inductor value that the DC/DC converter will not transfer from
LSP6501
1.6A, 1.3MHz, Boost DC-DC Converter
With Internal Switch
Discontinue-Current-Mode (DCM) to Continue-Current-Mode (CCM) or vise versa when VIN or IOUT change.
Such mode changing will cause the duty cycle of the Boost DC/DC converter becomes unstable.
5. S
han IOUT is
ode of lower dropout voltage can improve the system efficiency. Please
ification of the Schottky diode at the same time.
6. Minim
ose to 0%) or too
big (close to 100%). Small duty cycle happens when VOUT/VIN is low and big duty cycle happens when VOUT/VIN
refully examine whether the DC/DC converter under design
has n
around
72.5
LAY
election of Flywheel Diode
An Schottky diode that the voltage rating larger than 20V and the current rating larger t
recommended. Adopt a Schottky di
also check the leakage current spec
Note that the maximum working temperatures of many Schottky diodes are only 120°C. Please double
check the working temperature of the Schottky diode to ensure it is within the specification.
um & Maximum Duty Cycle Limitation
PWM ICs often have trouble to convert a VOUT from a VIN if the duty cycle is too small (cl
is High. DC/DC converter designers need to ca
such duty cycle limit problem, especially whe the nominal VOUT/VIN is already <1.2 or >5.
Note that factors like VIN deviation, component value deviation, temperature change, switching frequency
deviation…etc, can push the duty cycle to be much higher/lower than what we expect from the nominal
VOUT/VIN values. For example, the duty of a 3.3V input, 12V output DC/DC converter seems to be
%, but the actual duty cycle could be up to 80% if we include the voltage drops of output Schottky, VIN
trace drop, VIN ripple voltage drop, inductor line drop …etc.
OUT GUIDE LINE
VER. 1.2
7/10
PCB layout is an important stage for power circuit, especially the switching type DC/DC converter that providing
g high switching frequency. If PCB layout is not carefully done, the Boost converter
rious EMI problems.
se to the inductor.
h and according to the formula of
high current/voltage and usin
may be unstable or cause se
Use wide, short, and straightforward traces for high current paths. About the input capacitors, two or more
ceramic capacitors of several uF or bigger are recommended to be used. Place one of them very close to the VIN pin
of IC and ground, and at least one another very clo
It is very important to keep the loop of the SW pin, Schottky diode, output capacitor, and the GND pin of
LSP6501 as small as possible, and also minimize the length of the traces between these components, as shown in
the following Fig. 1. This is because the di/dt at these traces is very hig
dt
di
Lv ⋅=
the related voltage spikes will be very high if the trace inductance is high. Such voltage spikes not just cause EMC
problems, but may interfere or even damage the IC sometimes.
The most important is, it is better NOT to use via holes in the loop described above, because via holes have
high inductance.
LSP6501
1.6A, 1.3MHz, Boost DC-DC Converter
With Internal Switch
VER. 1.2
8/10
A304
VDD
SS FB
GND
DF
L
SW
FRE
Q
COMP
RP
CP2
COUT
CIN
CP1
R1
R2
VIN VOU
T
CSS
SHDN
ON/OFF
The loop needs to be
as small as possible.
L
S
P
650
1
Fig. 1
Second, keep all the analog components and signal traces, for example the VOUT sense trace, far away from the
noisy areas, that is, the areas near inductor, LSP6501 switch pin, and Schottky diode. If the VOUT sense trace is
close to the noisy area, large noise may be coupled into FB pin and cause VOUT value not accurate or unstable.
Please refer to Fig. 2.
A304
VDD
SS F
B
GN
D
DF
L
SW
FRE
Q
COM
P
RP
CP
2
COUT
CIN
C
P1
R1
R2
VIN VOUT
CS
S
SHDN
ON/OFF
Noisy area.
L
S
P
650
1
A
nalog components &
traces should be far away
from noisy area.
Fig. 2
About analog ground (the ground for feedback resistors, soft start capacitor, VOUT sensing resisters, and
compensation components), it is recommended to use short traces to connect these ground points and then directly
connect these traces to the GND pin of the IC. Please refer to Fig. 3 & Fig. 4.
LSP6501
1.6A, 1.3MHz, Boost DC-DC Converter
With Internal Switch
A304
VDD
SS FB
GND
DF
L
SW
FREQ
COMP
RP
CP2
COUT
CIN
CP1
R1
R2
VIN
VOUT
CSS
SHDN
ON/OFF
VER. 1.2
9/10
A3 04
VDD
SS FB
GND
DF
L
SW
FRE
Q
COMP
RP
CP2
COUT
CIN
CP1
R1
R2
VIN
VOU
T
CSS
SHDN
ON/OFF
Analog ground is independent
with power ground. It is also short
and far away from noisy area.
(Good)
Load
1
Load
2
It is bad to use other ground trace as
analog ground. It is even worse if the
traces are long, close to noisy area o
r
connected to high current devices.
(Bad)
Load
1
Load
2
L
S
P
650
1 L
S
P
650
1
Fig. 3 Fig. 4
A big ground plane (form input to out put) can help almost all the performance of the chip. Beside the ground
trace on the top layer, please use another layer as the ground layer.
ORDERING INFORMATION
Package:
MS: MSOP8L
Output Voltage:
Blank: Adj
Packing:
A: Tape & Real
Temperature Grade:
C: -20～85℃
LSP6501X X X X
MARKING INFORMATION
MSOP-8
LSP6501
LSC
VYWZ
LOGO
Part ID
LSP6501
1.6A, 1.3MHz, Boost DC-DC Converter
With Internal Switch
PACKAGE INFORMATION
VER. 1.2
10/10
K
DG
M
J
C
P
A
F
B
INCHES MILLIMETERS
MIN TYP MAX MIN TYP MAX
A 0.114 0.118 0.122 2.9 3 3.1
B 0.114 0.118 0.122 2.9 3 3.1
C 0.043 1.1
D 0.012 0.3
F 0.016 0.021 0.031 0.4 0.53 0.8
G 0.026BSC 0.65BSC
J 0.006 0.15
K 0 - 0.006 0 - 0.15
M 0º - 8º 0º - 8º
P 0.185 0.193 0.201 4.7 4.9 5.1
