Datasheet

THV6511_Rev.1.00_E
THV6511
Boost converter
Description
Features
THV6511 is a 1 channel boost converter IC.
Soft start / Over current protection / Under voltage lock
out protection / Thermal shut down are built in.
Mounted area is reducible by MSOP-8.
・Input voltage range : 2.5V – 5.5V
・Boost converter
Maximum output voltage : 18V
Switching limit current : 1.2A
Feedback voltage accuracy : +/-1.5%
Switching frequency : 640kHz / 1.2MHz
・Protection circuit
Soft start
Over current protection
Under voltage lock out protection
Thermal shut down
・MSOP-8pin package
Application
・Mobile phone display
・Car Navigator display
・Laptop/Netbook/Tablet PC display
Pin Configuration
Block Diagram
VLS
VIN
PC
1
8
SS
FB
2
7
OSC
EN
3
6
VCC
GND
4
5
LX
VCC
EN
LX
PC
UVLO
SS
Boost
FB
OSC
GND
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OSC
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THV6511_Rev.1.00_E
Absolute Maximum Ratings
Parameter
Symbol
VCC
VH
Pd
Tj
Tstg
VCC voltage
LX voltage
Power dissipation
Junction temperature (*1)
Storage temperature range
Rating
6.5
26
625
-40 to 125
-55 to +150
Units
V
V
mW
℃
℃
*1. The operating temperature range should perform a thermal design, after consulting the thermal characteristic. Please use it in the range which
does not exceed junction temperature.
Recommended Operating Conditions
Parameter
Min
2.5
-
VCC voltage
LX voltage
Typ
-
Max
5.5
18
Units
V
V
0.5
0.4
0.3
0.2
0
0.1
Power Dissipation [W]
0.6
0.7
Power Dissipation
-40
-20
0
20
40
60
80
100
120
140
160
Operating Temperature [℃]
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THV6511_Rev.1.00_E
Pin Description
Number
Name
Function
1
PC
Boost converter error
amplifier output pin
2
FB
3
4
EN
GND
5
LX
6
7
VCC
OSC
Boost converter feedback
voltage sense input pin
Enable pin.
Ground pin
Boost converter switching
output pin
Input supply voltage pin
Oscillator set pin
8
SS
Soft start set pin
Description
This pin is the boost converter error amplifier output.
Please connect resistance and capacitor to GND for phase
compensation.
This pin is feedback input for boost converter.
If low level voltage is impressed, PMIC is shutdown.
Ground of PMIC.
This pin is switching output of boost converter.
Power supply pin.
Low level voltage is 640kHz, high level voltage is 1.2MHz.
This pin is set by soft start for boost converter. Please
connect capacitor to GND for soft start time.
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THV6511_Rev.1.00_E
Electrical Characteristics
Parameter
(at VCC=3.3V , Ta=25℃, unless otherwise noted)
Symbol
Min
Typ
Max
Units
Vfb=1.34V(No switching)
-
350
500
uA
Vfb=1.14V(Switching)
-
2
5
mA
Ven<(0.3xVCC)
-
0.1
1
uA
Venh
0.7xVCC
-
-
V
Venl
-
-
0.3xVCC
V
Ren
-
250
-
kΩ
1.9
2.0
2.1
V
-
0.1
-
V
Input quiescent Current 1
Icc1
Input quiescent Current 2
Icc2
Standby current
Oscillator
and
Ist
EN
threshold
voltage
Oscillator and EN pull down
resistance
UVLO threshold voltage
Vuvlo
UVLO hysteresis voltage
Vuvloh
Boost
converter
switching
Test Conditions
VCC rising
Fosc1
Vosc<(0.3xVCC)
540
640
740
kHz
Fosc2
Vosc>(0.7xVCC)
1.0
1.2
1.4
MHz
Dmax
85
90
95
%
FB voltage
Vfb
1.222
1.240
1.258
V
LX ON-resistance
Ron
-
200
500
mΩ
LX current limit
Ilim
1.2
1.6
2.0
A
LX leakage current
Ioff
-
-
10
uA
frequency 1
Boost
converter
switching
frequency 2
Boost converter maximum duty
cycle
Vlx=18V
Soft start charge current
Iss
-
4
-
uA
FB short circuit voltage
Vuvp
-
1
-
V
FB short circuit delay time
Tuvp
-
54
-
msec
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THV6511_Rev.1.00_E
current through the inductor equals to the current
Function
computed by the compensator. This loop acts within one
Boost converter
switching cycle. A slope compensation ramp is added to
The LCD panel VLS supply is generated from a
suppress sub-harmonic oscillations. An outer voltage
high-efficiency PWM boost converter operating with
feedback loop subtracts the voltage on the FB pin from
current mode control, and the switching frequency is
the internal reference voltage and feeds the difference to
selectable 640kHz or 1.2MHz. During the on-period, TON,
the compensator operational transconductance amplifier.
the synchronous FET connects one end of the inductor to
This amplifier is compensated by an external R-C
ground, therefore increasing the inductor current. After
network to allow the user to optimize the transient
the FET turns off, the inductor switching node, LX, is
response and loop stability for the specific application
charged to a positive voltage by the inductor current. The
conditions.
freewheeling diode turns on and the inductor current
The output voltage VLS can be set by external resistor
flows to the output capacitor.
divider R1 and R2 connected to FB.
The converter operates in continuous conduction mode
 R 
VLS  VFB  1  1 
 R2 
when the load current IVLS is at least one-half of the
inductor ripple current ΔIrip.
I IN 
I rip
I rip
VLS
2
(VLS  VIN )  VIN

L  FOSC  VLS
LX
R1
FB
The output voltage (VLS) is determined by the duty
R2
cycle(D) of the power FET on-time and the input
voltage, VIN.
VLS 
VIN
1 D
Fig. 1
FB setup
The average load current, IVLS, can be calculated from
[Compensator selection]
the power conservation law.
This current mode boost converter has a current sense
  V IN I IN  VLS  I VLS
loop and a voltage feedback loop. The
where η is the power conversion efficiency. For a lower
loop does not need any
load current, the inductor current would decay to zero
feedback loop is
during the free-wheeling period and the
R-C network
would be disconnected
from the
output node
current sense
compensation. The voltage
compensated by an external series
RPC and CPC from PC pin to ground.
inductor for the
RCOMP is set to define the high frequency integrator gain
remaining portion of the switching period. The converter
for loop bandwidth which relates to the transient
would operate in the
response. CPC is set to ensure the loop stability.
discontinuous conduction mode .
Current mode control is well known for its robustness
and fast transient response. An inner current feedback
[Output capacitor selection]
loop sets the on-time and the duty cycle such that the
The output voltage ripple due to converter switching is
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THV6511_Rev.1.00_E
determined by the output capacitor
total capacitance,
the maximum input and output current that the converter
COUT, and the output
VLS rip 
can operate with before reaching the current limit of the
D  I OUT
 I peak  ESR
FOSC  COUT
I peak  I IN 
chip or the rated current of the inductor.
I peak  I IN 
I rip
2
I rip
2
 I MAX
For example, ΔIrip could be set to 20% of IMAX
The first ripple component can be reduced by increasing
COUT. Changing COUT may require adjustment of
compensation R and C in order to provide adequate
Protection circuits
phase margin and loop bandwidth.
Under voltage lock out protection (UVLO)
The second ripple component can be reduced by
The UVLO function is carried in order to prevent
selecting low-ESR ceramic capacitors and using several
malfunction in the state where input voltage is low. A
smaller capacitors in parallel instead of just one large
boost converter is suspended to the power supply voltage
capacitor.
which can carry out operational stability. UVLO is
released by more than 1.9V input voltage. And a boost
[Inductor selection]
converter carries out, after starting soft start operation.
To prevent magnetic saturation of the inductor core the
If the feedback voltage pin FB is below 1V, the
inductor has to be rated for a maximum current larger
THV6511 activates an internal fault timer. If any
than IPK in a given application. Since the chip provides
condition indicates a continuous fault for the fault timer
current limit protection of 1.6A, it is generally
duration 54ms, the IC sets the fault latch to shut down its
recommended that the inductor be rated at least for 1.6A.
output except the reference. Once the fault condition is
Selection of the inductor requires trade-off between the
removed, cycle the input voltage (below the UVLO
physical size (footprint x height) and its electrical
falling threshold) to clear the fault latch and reactivate
properties (current rating, inductance, resistance). Within
the device.
a given footprint and height, an inductor with larger
inductance typically comes with lower current rating and
often larger series resistance. Larger inductance typically
Soft start (SS)
requires more turns on the winding, a smaller core gap or
The boost converter carries the soft start function in
a core material with a larger relative permeability. An
order to prevent the rush current at a start-up. This
inductor with a larger physical size has better electrical
function is to raise output voltage slowly. It is because
properties than a smaller inductor.
overshooting and rush current occur when input voltage
It is desirable to reduce the ripple current ΔIrip in order to
is inputted. This function is available in THV6511only.
reduce voltage noise on the input and output capacitors.
This IC uses a soft start circuit to minimize the inrush
In practice, the inductor is often much larger than the
current. Connecting a capacitor CSS between SS pin and
capacitors and it is easier and cheaper to increase the size
ground determines the soft start time TSS.
of the capacitors. The ripple current
TSS 
ΔIrip is then chosen
the largest possible while at the same time not degrading
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1.24V  C SS
4A
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THV6511_Rev.1.00_E
If CSS is too small or not present at all, the
internal soft
start circuit ensures that the soft start period is at least
3.4ms.
Over current protection (OCP)
In order to restrict the over-current by the abnormalities
of load, etc., the over-current protection circuit is built in.
Over-current detection of pulse-by-pulse system is
adopted. An output transistor is turned off if the current
which flows into an output transistor reaches boost
converter limit current (Ilim). An over-current protection
circuit detects the peak current of an inductor.
Input-and-output voltage and ripple current is taken into
consideration.
Thermal shut down (TSD)
In order to prevent destruction by heat, the thermal
shutdown circuit is built in. If the junction temperature
Tj is 125oC or more, the thermal shutdown circuit will
operate and it will stop switching operation. Moreover,
the hysteresis of a thermal shutdown circuit is 20oC. If Tj
falls, output voltage will return.
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Package Dimensions
MSOP-8pin
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Notices and Requests
1. The product specifications described in this material are subject to change without prior notice.
2. The circuit diagrams described in this material are examples of the application which may not always apply to the
customer’s design. We are not responsible for possible errors and omissions in this material. Please note if errors or
omissions should be found in this material, we may not be able to correct them immediately.
3. This material contains our copyright, know-how or other proprietary. Copying or disclosing to third parties the
contents of this material without our prior permission is prohibited.
4. Note that if infringement of any third party's industrial ownership should occur by using this product, we will be
exempted from the responsibility unless it directly relates to the production process or functions of the product.
5. This product is presumed to be used for general electric equipment, not for the applications which require very high
reliability (including medical equipment directly concerning people's life, aerospace equipment, or nuclear control
equipment). Also, when using this product for the equipment concerned with the control and safety of the
transportation means, the traffic signal equipment, or various Types of safety equipment, please do it after applying
appropriate measures to the product.
6. Despite our utmost efforts to improve the quality and reliability of the product, faults will occur with a certain small
probability, which is inevitable to a semi-conductor product. Therefore, you are encouraged to have sufficiently
redundant or error preventive design applied to the use of the product so as not to have our product cause any social
or public damage.
7. Please note that this product is not designed to be radiation-proof.
8. Customers are asked, if required, to judge by themselves if this product falls under the category of strategic goods
under the Foreign Exchange and Foreign Trade Control Law.
9. The product or peripheral parts may be damaged by a surge in voltage over the absolute maximum ratings or
malfunction, if pins of the product are shorted by such as foreign substance. The damages may cause a smoking
and ignition. Therefore, you are encouraged to implement safety measures by adding protection devices, such as
fuses.
THine Electronics, Inc.
sales@thine.co.jp
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