ETC EUP2621

芯美电子
EUP2621
620kHz/1.25MHz Step-up DC/DC Converter
DESCRIPTION
FEATURES
The EUP2621 is a high performance current mode, PWM
step-up converter with pin selectable operating frequency.
With an internal 1.6A, 200mΩ MOSFET, it can generate
12V at up to 400mA output current from a 5V supply. The
selectable 620kHz and 1.25MHz allows smaller inductors
and faster transient response. An external compensation pin
gives the user greater flexibility in setting loop
compensation allowing the use of low ESR Ceramic output
capacitors. Soft-start is controlled with an external
capacitor, which determines the input current ramp rate
during start-up.
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z
z
z
z
z
z
z
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When shut down, it draws＜10µA of current and can
operate down to 2.5V input supply. These features along
with 1.25MHz switching frequency makes it an ideal
device for portable equipment and TFT-LCD displays.
APPLICATIONS
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z
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The EUP2621 is available in an 8-pin MSOP package. The
device is specified for operation over the full -40°C to
+85°C temperature range.
90% Efficiency
1.6A, 200mΩ Power MOSFET
2.5V to 5.5V Input Range
Adjustable Output Voltage up to 18V
620kHz/1.25MHz Switching Frequency Selection
Adjustable Soft-Start
Internal Thermal Protection
Small MSOP-8 package
RoHS Compliant and 100% Lead (Pb)-Free
TFT-LCD Displays
DSL Modems
Set-Top Boxes
PCMCIA Cards
Portable Equipment
Handheld Devices
Typical Application Circuit
Figure 1. 5V to 12V Step-Up
DS2621 Ver 1.0 July .2006
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EUP2621
Figure 2. Triple Output TFT LCD Power Supply
Pin Configurations
Part
Number
Pin Configurations
EUP2621
MSOP-8
Pin Description
PIN
PIN
COMP
1
FB
2
SHDN
GND
SW
VIN
3
4
5
6
FSEL
7
SS
8
DS2621 Ver 1.0 July .2006
DESCRIPTION
Compensation pin. Output of the internal error amplifier. Capacitor and resistor
from COMP pin to ground.
Voltage feedback pin. Internal reference is 1.24V NOMINAL. Connect a resistor
divider from VOUT. VOUT=1.24V (1+R1/R2).
Shutdown control pin. Pull SHDN low to turn off the device.
Analog and power ground.
Power switch pin. Switch connected to the drain of the internal power MOSFET.
Analog power input pin.
Frequency select pin. When FSEL is connected to GND, switching frequency is set
to 620kHz. When connected to VIN, switching frequency is set to 1.25MHz
Soft-start control pin. Connect a capacitor to control the converter start-up
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EUP2621
Ordering Information
Order Number
Package Type
Marking
Operating Temperature Range
EUP2621MIR1
MSOP-8
xxxx
P2621
-40 °C to 85°C
EUP2621
□ □ □
□
Lead Free Code
1: Lead Free 0: Lead
Packing
R: Tape & Reel
Operating temperature range
I: Industry Standard
Package Type
M: MSOP
Block Diagram
DS2621 Ver 1.0 July .2006
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EUP2621
Absolute Maximum Ratings
„
„
„
„
„
„
„
VIN
--------------------------------------------------------------------------------------6V
SW Voltages ---------------------------------------------------------------------------- 20V
FB Voltage
----------------------------------------------------------------------------2V
SHDN Voltage ------------------------------------------------------------------------6V
Junction Temperature ------------------------------------------------------------------ 150°C
Lead Temp (Soldering, 10sec) --- --------------------------------------------------300°C
ESD Ratings
Human Body Model ---------------------------------------------------------------- 2kV
Operating Conditions
„
„
„
Operating Temperature --------------------------------------------------------- -40°C to 85°C
Supply Voltage -------------------------------------------------------------------- 2.5V to 5.5V
SW Voltage Max ---------------------------------------------------------------------18V
Electrical Characteristics
VIN=VSHDN=3V. TA=-40℃to 85℃.Typical values are at TA=25℃.Unless otherwise noted.
EUP2621
Symbol
Parameter
Conditions
Min
Typ Max.
VIN
Input Voltage Range
VOUT<18V
2.5
5.5
UVLO
IQ
VIN Undercoltage Lockout
Quiescent Current
SW Remains off below this level.
VIN Rising,20mV hysteresis
Unit
V
2.15
2.35
V
FB=2V (Not Switching)
0.5
0.8
mA
FB=0V（Switching）
1.5
2
mA
VSHDN=0V
0.1
1.24
10
1.27
uA
1.92
VFB
FB Regulation Voltage
IB
%VFB/
△VIN
%VFB/
△ILOAD
gm
FB Input Bias Current
VFB=1.24V
100
250
nA
FB Line Regulation
2.5V ≤ VIN ≤ 5.5V
0.08
0.15
%/V
FB Load Regulation
VOUT=8V,Iload=30mA to200 mA
6.7
Error Amp Transconductance
△I=4uA
1.20
20
AV
Error Amp Voltage Gain
Fs
Switching Frequency
DMAX
Maximum Duty Cycle
ICL
Switch Current Limit
55% Duty Cycle
Switch MOSFET On Resistance
IL
45
V
mV/A
95
500
umho
V/V
FSLCT=Ground
500
620
740
kHz
FSLCT=VIN
900
1250
1500
kHz
94
％
1.5
1.6
A
ISW=500mA
0.2
0.45
Ω
Switch Leakage Current
VSW=18V
0.2
20
uA
ISS
Charge Current
VSS=0V
5
8
uA
VIL
SHDN, FREQ Input Low Voltage
0.5
V
VIH
SHDN, FREQ Input High Voltage
RDSON
IFSLCT
3
V
2
FSLCT Pull Down Current
DS2621 Ver 1.0 July .2006
1.3
2.4
5.5
8.2
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uA
芯美电子
EUP2621
Typical Operating Characteristics
620kHz Switching Frequency vs. Temperature
620kHz Efficiency vs. Load Current
630
90
SWITCHING FREQUENCY (kHA)
95
VIN=5.5V
VOUT=8V
85
EFFICIENCY (%)
80
VIN=3V
75
70
VIN=2.5V
65
60
55
50
45
40
35
30
1
10
100
620
610
VIN=5.5V
600
590
VIN=2.5V
580
570
560
550
-40 -30 -20 -10
1000
LOAD CURRENT (mA)
0
10
20
30
40
50
60
70
80
90
0
TEMPERATURE( C)
Switching Current Limit vs. Temperature
FSLCT Pin Current vs. FSLCT Pin Voltage
VOUT=8V
3.2
6.4
3.0
6.2
CURRENT LIMIT (A)
FSLCT PIN CURRENT(uA)
6.6
6.0
0
T=-40 C
5.8
0
T=25 C
5.6
0
T=85 C
5.4
5.2
VIN=5.5V
2.8
2.6
2.4
VIN=3V
2.2
VIN=2.5V
2.0
5.0
2.5
3.0
3.5
4.0
4.5
5.0
-40 -30 -20 -10
5.5
0
10
20
30
40
50
60
70
80
90
80
90
0
TEMPERATURE( C)
FSLCT VOLTAGE(V)
620kHz Switching IQ vs. Temperature
2.50
3.75
2.25
VIN=5.5V
2.00
1.75
1.50
3.25
3.00
2.75
2.50
2.25
2.00
VIN=2.5V
1.25
VIN=5.5V
3.50
SWITCHING IQ (mA)
SWITCHING IQ (mA)
1.25MHz Switching IQ vs. Temperature
4.00
VIN=2.5V
1.75
1.00
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
1.50
-40
90
-20
-10
0
10
20
30
40
50
60
TEMPERATURE( C)
TEMPERATURE( C)
DS2621 Ver 1.0 July .2006
-30
0
0
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芯美电子
EUP2621
1.25MHz Non-switching IQ vs. Input Voltage
620kHz Non-switching IQ vs. Input Voltage
0.60
0.65
0.55
0.60
0
0.50
0
NON-SWITCHING IQ (mA)
NON-SWITCHING IQ (mA)
T= 25 C
0
T= 85 C
T= 25 C
0.45
0.40
0
T= - 40 C
0.35
0.30
2.5
3.0
3.5
4.0
4.5
5.0
0
0.55
0.50
0.45
0
T= - 40 C
0.40
0.35
2.5
5.5
T= 85 C
3.0
3.5
4.0
4.5
5.0
5.5
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
620kHz Switching IQ vs. Input Voltage
4.0
2.3
1.25MHz Switching IQ vs. Input Voltage
2.2
2.1
3.5
1.9
SWITCHING IQ (mA)
SWITCHING IQ (mA)
2.0
0
T= 25 C
0
T= - 40 C
1.8
1.7
1.6
1.5
0
T= 85 C
1.4
1.3
0
T= 25 C
3.0
0
T= - 40 C
2.5
0
T= 85 C
2.0
1.2
1.1
1.0
2.5
3.0
3.5
4.0
4.5
5.0
1.5
2.5
5.5
3.0
3.5
4.0
4.5
5.0
5.5
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
NMOS RDSON vs. Input Voltage
SS Pin Current vs. Temperature
6.8
0.24
6.6
0.20
NMOS RDSON (O)
SS PIN CURRENT(uA)
0.22
6.4
6.2
VIN=5.5V
6.0
5.8
5.6
5.4
VIN=2.5V
0.18
0
-30
-20
-10
0
10
20
30
0.14
0.12
40
50
60
70
80
0.10
2.5
90
0
T = - 40 C
3.0
3.5
4.0
4.5
INPUT VOLTAGE (V)
0
TEMPERATURE( C)
DS2621 Ver 1.0 July .2006
T = 25 C
0.16
5.2
5.0
-40
0
T = 85 C
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5.0
5.5
芯美电子
EUP2621
Inductor Selection
The inductor selection determines the output ripple
voltage, transient response, output current capability, and
efficiency. Its selection depends on the input voltage,
output voltage, switching frequency, and maximum output
current. For most applications, a 4.7µH inductor is
recommended for 1.25MHz application and a 10µH
inductor is recommended for 620kHz application. The
inductor maximum DC current specification must be
greater than the peak inductor current required by the
regulator. The peak inductor current can be calculated:
Application Information
Boost Converter Operations
In steady state operating and continuous conduction mode
where the inductor current is continuous, the boost
converter operates in two cycles. During the first cycle,
the internal power FET turns on and the Schottky diode is
reverse biased and cuts off the current flow to the output.
The output current is supplied from the output capacitor.
The voltage across the inductor is VIN and the inductor
current ramps up in a rate of VIN/L, L is the inductance.
The inductance is magnetized and energy is stored in the
inductor. The change in inductor current is:
×V
× (V
−V )
V
OUT
OUT
IN
OUT
IN
I
=
+ 1/2 ×
× FREQ
L×V
V
L(PEAK)
OUT
IN
I
V − VOUT
∆I L = ∆T2 × IN
L
∆T2 =
1- D
F
SW
Output Capacitor
Low ESR capacitors should be used to minimized the
output voltage ripple. Multilayer ceramic capacitors (X5R
and X7R) are preferred for the output capacitors because
of their lower ESR and small packages. Tantalum
capacitors with higher ESR can also be used. The output
ripple can be calculated as:
For stable operation, the same amount of energy stored in
the inductor must be taken out. The change in inductor
current during the two cycles must be the same.
∆I1+∆I2=0
I
×D
OUT
∆V =
+I
× ESR
OUT
O
F
×C
SW
O
V
D
1 − D VIN − VOUT
× IN +
×
=0
L
L
F
F
SW
SW
Choose an output capacitor to satisfy the output ripple and
load transient requirement. A 10µF to 22µF ceramic
capacitor is suitable for most application.
For noise sensitive application, a 0.1µF placed in parallel
with the larger output capacitor is recommended to reduce
the switching noise coupled from the SW switching node.
V
1
OUT
=
−
1
D
V
IN
Schottky Diode
In selecting the Schottky diode, the reverse break down
voltage, forward current and forward voltage drop must
be considered for optimum converter performance. The
diode must be rated to handle 1.6A, the current limit of
the EUP2621. The breakdown voltage must exceed the
maximum output voltage. Low forward voltage drop, low
leakage current, and fast reverse recovery will help the
converter to achieve the maximum efficiency.
Output Voltage
An external feedback resistor divider is required to divide
the output voltage down to the nominal 1.24V reference
voltage. The current drawn by the resistor network should
be limited to maintain the overall converter efficiency.
The maximum value of the resistor network is limited by
the feedback input bias current and the potential for noise
being coupled into the feedback pin. Selecting R2 in the
range of 10kΩ to 50 kΩ. The boost converter output
voltage s determined by the relationship:
 R
V
=V
× 1 + 1
OUT
FB 
R

2




The nominal VFB voltage is 1.24V
DS2621 Ver 1.0 July .2006
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EUP2621
Input Capacitor
The value of the input capacitor depends the input and
output voltages, the maximum output current, the
inductor value and the noise allowed to put back on the
input line. For most applications, a minimum 10µF is
required. For applications that run close to the maximum
output current limit, input capacitor in the range of 22µF
to 47µF is recommended. The EUP2621 is powered
from the VIN. High frequency 0.1µF by-pass cap is
recommended to be close to the VIN pin to reduce
supply line noise and ensure stable operation.
Maximum Output Current
The output current capability of the EUP2621 is a
function of current limit, input voltage, operating
frequency, and inductor value. The output current
capability is governed by the following equation:
(
I L = I L - AVG + 1 / 2 × ∆I L
Where:
IL=MOSET current limit
I L - AVG =average inductor current
∆I L =inductor ripple current
Loop Compensation
The EUP2621 incorporates an transconductance
amplifier in its feedback path to allow the user some
adjustment on the transient response and better
regulation. The EUP2621 uses current mode control
architecture which has a fast current sense loop and a
slow voltage feedback loop. The fast current feedback
loop does not require any compensation. The slow
voltage loop must be compensated for stable operation.
The compensation network is a series RC network from
COMP pin to ground. The resistor sets the high
frequency integrator gain for fast transient response and
the capacitor sets the integrator zero to ensure loop
stability. For most applications, the compensation
resistor in the range of 2K to 30K and the compensation
capacitor in the range of 1nF to 10nF.
∆I L =


VIN ×  VO + VDIODE − V  − VIN 


IN 
L ×  VO + V

DIODE
 × F
 S
VDIODE = Schottky diode forward voltage, typically,
0.6V
FS = switching frequency, 620KHz or 1.25MHz
I
I L - AVG = OUT
1−D
D = MOSFET turn-on ratio:
D =1−
Soft-Start
The soft-start is provided by an internal 5µA current
source charges the external CSS, the peak MOSFET
current is limited by the voltage on the capacitor. This in
turn controls the rising rate of the output voltage. The
regulator goes through the start-up sequence as well after
the SHDN pin is pulled to HI.
VIN
VOUT + V
DIODE
Layout Considerations
Good PC board layout and routing are required in
high-frequency switching power supplies to achieve good
regulation, high efficiency, and stability. It is strongly
recommended that the evaluation kit PC board layouts be
followed as closely as possible. Place power components
as close together as possible, keeping their traces short,
direct, and wide. Avoid interconnecting the ground pins
of the power components using vias through an internal
ground plane. Instead, keep the power components close
together and route them in a “star” ground configuration
using component-side coper, then connect the star ground
to internal ground using multiple vias.
Frequency Selection
The EUP2621 switching frequency can be user selected
to operate at either at constant 620kHz or 1.25MHz.
Connecting FSEL pin to ground sets the PWM switching
frequency to 620kHz. When connect FSEL high or VDD,
switching frequency is set to 1.25MHz.
Shut-Down Control
The EUP2621 shuts down to reduce the supply current
to 0.1μA when SHDN is low. In this mode, the internal
reference, error amplifier, comparators, and biasing
circuitry turn off while the N-channel MOSFET is
turned off. The boost converter’s output is connected to
IN via the external inductor and catch diode.
DS2621 Ver 1.0 July .2006
)
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EUP2621
Packaging Information
MSOP-8
NOTE
1. Package body sizes exclude mold flash and gate burrs
2. Dimension L is measured in gage plane
3. Tolerance 0.10mm unless otherwise specified
4. Controlling dimension is millimeter. Converted inch dimensions are not necessarily exact.
SYMBOLS
A
A1
A2
b
C
D
E
E1
e
L
y
θ
DS2621 Ver 1.0 July .2006
DIMENSIONS IN MILLIMETERS
MIN.
NOM.
MAX.
0.81
0.95
1.10
0.05
0.09
0.15
0.76
0.86
0.97
0.28
0.30
0.38
0.13
0.15
0.23
2.90
3.00
3.10
4.70
4.90
5.10
2.90
3.00
3.10
-----0.65
----0.40
0.53
0.66
----------0.10
0
-----6
DIMENSIONS IN INCHES
MIN.
NOM.
MAX.
0.032
0.0375
0.043
0.002
0.004
0.006
0.030
0.034
0.038
0.011
0.012
0.015
0.005
0.006
0.009
0.114
0.118
0.122
0.185
0.193
0.201
0.114
0.118
0.122
-----0.026
-----0.016
0.021
0.026
----------0.004
0
-----6
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