AIC AIC1554 Low-noise synchronous pwm step-down dc/dc converter Datasheet

AIC1555
Low-Noise Synchronous PWM Step-Down
DC/DC Converter
FEATURES
95% Efficiency or up
700mA Guaranteed Output Current.
Adjustable Output Voltage from 0.75V to VIN
of a range from +2.5V to 6.5V.
The AIC1555 is a low-noise pulse-width-
Very Low Quiescent Current: 35µA (Typ.).
Fixed- 500KHz or Adjustable Frequency
Synchronous PWM Operation.
Synchronizable external Switching Frequency
up to 1MHz.
Constant Over-current-protection mode.
Accurate Reference: 0.75V (±2.5%).
100% Duty Cycle in Dropout.
Low Profile 8-Pin MSOP Package.
handy-terminals.
modulated (PWM) DC-DC step-down converter.
It powers logic circuits in PDAs and small
wireless systems such as cellular phones,
The device features an internal synchronous
rectifier for high conversion efficiency. Excellent
noise
characteristics
operation
provide
and
easy
fixed-frequency
post-filtering.
The
AIC1555 is ideally suited for Li-ion battery
applications. It is also suitable for +3V or +5V
fixed input applications. The device can operate
in either one of the following four modes.
APPLICATIONS
DESCRIPTION
PDAs.
Digital Still Cameras.
Handy-Terminals.
Cellular Phones.
CPU I/O Supplies.
Cordless Phones.
Notebook Chipset Supplies.
Battery-Operated Devices (4 NiMH/ NiCd or 1
Li-ion Cells).
(1) Forced PWM mode operates at a fixed
frequency regardless of the load.
(2) Synchronizable PWM mode allows the
synchronization
switching
by
frequency
using
an
external
with
a
minimum
harmonics.
(3) PWM/PFM Mode extends battery life by
switching to a PFM pulse-skipping mode
under light loads.
(4) Shutdown mode sets device to standby,
reducing supply current to 0.1µA or under.
The AIC1555 can deliver over 700mA output
current. The output voltage can be adjusted
from 0.75V to VIN ranging from +2.5V to +6.5V.
Other features of the AIC1555 include low
quiescent current, low dropout voltage, and a
0.75V reference of ±2.5% accuracy. It is
available
in
a
space-saving
8-pin
MSOP
package.
Analog Integrations Corporation
Si-Soft Research Center
3A1, No.1, Li-Hsin Rd. I , Science Park , Hsinchu 300, Taiwan , R.O.C.
TEL: 886-3-5772500
FAX: 886-3-5772510
www.analog.com.tw
DS-1555G-01 121608
1
AIC1555
TYPICAL APPLICATION CIRCUIT
VIN= 2.5V to 6.5V
1
BP
CIN
22µF
CBP
0.1µF
LX
2 BP
3
SHDN
4
FB
GND 7
SYNC/ 6
MODE
RT
VOUT = 1.8V
L1
8
VIN
*
5
6.8µH
D1
SS12
Optional
CF
R1
820K
12pF
AIC1555
CO
R2
560K
22µF
CIN: TAIYO YUDEN LMK316F226ZL-T Ceramic capacitor
CO: TAIYO YUDEN LMK316F226ZL-T Ceramic capacitor
L1: TDK SLF6025-6R8M1R3
* Note: Efficiency can boost 2% to 4% if D1 is connected.
D1: GS SS12
ORDERING INFORMATION
AIC1555XXXXX
PACKING TYPE
TR: TAPE & REEL
TB: TUBE
PACKAGING TYPE
O8:MSOP8
PIN CONFIGURATION
TOP VIEW
VIN 1
BP 2
SHDN 3
FB 4
8 LX
7 GND
6 SYNC/MODE
5 RT
P: Lead Free
G: Green Package
Example: AIC1555PO8TR
In MSOP Lead Free Package &
Taping & Reel Packing Type
2
AIC1555
ABSOLUTE MAXIMUM RATINGS
VIN, BP, SHDN, SYNC/MODE, RT to GND
-0.3 to +7V
BP to VIN
.-0.3 to 0.3V
LX to GND
-0.3 ~ (VIN+0.3V)
FB to GND
-0.3 ~ (VBP+0.3V)
Operating Temperature Range
Thermal Resistance Junction to Case
Thermal Resistance Junction to Ambient
-40°C ~ 85°C
MSOP8
MSOP8
75°C/W
180°C/W
(Assume no ambient airflow, no heatsink)
Junction Temperatrue
Storage Temperature Range
Lead Temperature (Soldering. 10 sec)
125°C
-65°C ~ 150°C
260°C
Absolute Maximum Ratings are those values beyond which the life of a device may be Impaired.
TEST CIRCUIT
Refer to Typical Application Circuit.
3
AIC1555
ELECTRICAL CHARACTERISTICS
(VIN=+3.6V, TA=+25°°C, SYNC/MODE =GND, SHDN =IN, unless otherwise specified.) (Note1)
PARAMETER
Input Voltage Range
Output Adjustment Range
Feedback Voltage
SYMBOL CONDITIONS
MIN
6.5
V
VOUT
VREF
VIN
V
VFB
0.731
0.769
V
+2.5
%
Duty Cycle = 100% to 23%
IOUT = 0 to 700mA
IFB
VFB = 1.4V,
P-Channel On-Resistance PRDS(ON) ILX = 100mA
N-Channel On-Resistance NRDS(ON) ILX = 100mA
P-Channel Current-Limit
-50
0.65
VIN = 2.5V
0.38
VIN = 3.6V
0.32
VIN = 2.5V
0.38
VIN = 5.5V, VLX = 0 or 5.5V
fOSC
dutyMAX
UVLO
VIN rising, typical hysteresis is
85mV
SHDN , SYNC/MODE, LIM
Logic Input Low
VIL
SHDN , SYNC/MODE, LIM
Pulse Width
SHDN , SYNC/MODE, LIM
High or low
Ω
Ω
2.1
A
35
70
µA
0.1
1
µA
-20
0.1
20
µA
400
500
600
KHz
1000
KHz
100
VIH
SYNC/MODE Minimum
0.65
nA
1.5
500
Logic Input High
Logic Input Current
1
leakage current
SYNC Capture Range
Threshold
%
0.32
SHDN = LX = GND, includes LX
LX Leakage Current
-1.3
VIN = 3.6V
VFB = 1.4V, LX unconnected
Shutdown Supply Current
%
50
SYNC/MODE = GND,
Quiescent Current
+1
0.01
(Note 2)
Threshold
Undervoltage Lockout
0.75
-2.5
Load Regulation
Maximum Duty Cycle
UNITS
2.5
Line Regulation
Oscillator Frequency
MAX
VIN
Feedback Accuracy
FB Input Current
TYP
1.9
%
2.0
2.1
2
-1
500
V
V
0.1
0.4
V
1
µA
nS
Note 1: Specifications are production tested at TA=25°C. Specifications over the -40°C to 85°C operating
temperature range are assured by design, characterization and correlation with Statistical Quality
Controls (SQC).
Note 2: Maximum specification is guaranteed by design, not production tested.
4
AIC1555
TYPICAL PERFORMANCE CHARACTERISTICS
(TA=25oC, VIN=3.6V, SYNC/MODE=GND, with Schottky diode D1, unless otherwise noted.)
100
100
80
70
VIN=5.0V
60
VIN=6.5V
80
70
VIN=6.5V
VIN=5.0V
60
VIN=3.3V
VIN=2.3V
50
50
40
VIN=2.1V
90
VIN=2.1V
Efficiency (%)
Efficiency (%)
90
VOUT=1.5V
VOUT=1.2V
0.1
1
10
100
40
0.1
1000
Load Current (mA)
1
10
Load Current (mA)
100
1000
Fig. 2 Load Current vs. Efficiency (VOUT=1.5V)
Fig. 1 Load Current vs. Efficiency (VOUT=1.2V)
(Refer to typical application circuit)
(Refer to typical application circuit)
(Refer to typical application circuit)
100
100
VIN=3.3V
90
VIN=2.1V
90
Efficiency (%)
Efficiency (%)
VIN=3.3V
80
70
VIN=6.5V
VIN=5.0V
60
80
70
VIN=6.5V
VIN=5.0V
60
50
50
VOUT=2.5V
VOUT=1.8V
40
40
0.1
1
10
100
0.1
1
1000
Load Current (mA)
Fig. 4
Fig. 3 Load Current vs. Efficiency (VOUT=1.8V)
10
100
1000
Load Current (mA)
Load Current vs. Efficiency (VOUT=2.5V)
(Refer to typical application circuit)
(Refer to typical application circuit)
100
100
VIN=3.6V
VIN=3.6V
90
90
80
80
Efficiency (%)
Efficiency (%)
VIN=4.2V
70
60
50
VIN=6.5V
70
60
40
1
Fig. 5
10
100
Load Current (mA)
Load Current vs. Efficiency (VOUT=3.0V)
(Refer to typical application circuit)
VIN=4.2V
50
VOUT=3.0V
40
0.1
VIN=5.0V
1000
0.1
1
10
VOUT=3.3V
100
1000
Load Current (mA)
Fig. 6 Load Current vs. Efficiency (VOUT=3.3V)
(Refer to typical application circuit)
5
AIC1555
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
0.765
100
W/ Schottky Diode
90
0.760
Reference Voltage (V)
SYNC= GND
Efficiency (%)
80
W/o Schottky Diode
70
60
SYNC= VIN
50
40
VOUT=3.0V
30
0.1
Fig. 7
1
10
Load Current (mA)
100
540
0.755
0.750
0.745
0.740
0.735
0.725
-50
1000
-25
0
25
50
75
100
125
Temperature (°C)
Fig. 8 Reference Voltage vs. Temperature
Load Current vs. Efficiency (W/ or W/O Schottky Diode)
550
540
VIN=3.6V
530
530
Frequency (KHz)
Frequency (KHz)
VIN=3.6V
0.730
550
520
510
500
490
480
520
510
500
490
480
470
470
460
460
450
-40
-20
0
20
40
60
80
100
450
120
2.0
Temperature (°C)
Fig. 9
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
Supply Voltage (V)
Fig. 10 Frequency vs. Input Voltage
Oscillator Frequency vs. Temperature
1.82
0.44
0.42
1.80
Output Voltage (V)
Main Switch
0.40
RDSON (mΩ)
0.38
0.36
0.34
0.32
VIN=3.6V
1.78
1.76
0.30
0.28
1.74
Synchronous Switch
0.26
2.0
2.5
3.0
3.5
4.0
4.5
5.0
Supply Voltage (V)
Fig. 11 RDSON vs. Supply Voltage
5.5
6.0
1.72
1
10
100
1000
Load Current (mA)
Fig. 12 Output Voltage vs. Load Current
6
AIC1555
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
300
100
VOUT=1.8V
PWM/PFM
90
A)
250
80
Efficiency (%)
DC Supply Current (
μ200
SYNC/PWM=IN
150
100
70
PWM
60
50
40
SYNC/PWM=GND
30
VIN=3.6V
VOUT=1.8V
50
20
0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
10
0.1
1
10
Supply Voltage (V)
Fig. 13 DC Supply Current vs. Supply Voltage
100
1000
Load current (mA)
Efficiency vs. Load current
Fig. 14
1000
Operation Frequency (KHz)
900
800
700
600
500
2250
2000
Fig. 15
1500 1250 1000 750
Tuning Resistor RT (kΩ)
1750
500
250
Operation Frequency vs. Tuning Resistor
Fig. 16
VOUT=1.8V;
ILOAD=50mA to 500mA;
SYNC/MODE=IN
Fig. 17 Load Transient Response
Over Current Protection
VOUT=1.8V;
ILOAD=50mA to 500mA;
SYNC/MODE=GND
Fig. 18
Load Transient Response
7
AIC1555
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN=3.3V to 5V,
IOUT=1.8V;
ILOAD=200mA to 500mA;
SYNC/MODE=IN
Fig. 19 Line Transient Response
Fig. 20
Start-up from Shutdown, RLOAD=3Ω
VIN=3.6V, VOUT=1.8V, ILOAD=800mA
VOUT
VIN=3.6V; VOUT=1.8V;
ILOAD=500mA
VLX
SYNC/MODE=IN
Fig. 21 Switching Waveform
Fig. 22 Output Ripple voltage
8
AIC1555
BLOCK DIAGRAM
BP
Chip S upply
10
0.75V
RE F
C urrent A M P .
S HDN
V IN
V IN
+
X 5
5
S lope
500K H z
O scillator
RT
Q1
x1
Current Lim it
Com parator
Com pen sation
Q2
X20
Frequenc y
S YNC
+
S election
P hase
Com pensation
FB
FB
REF
E rro r
A MP .
PW M
Com parator
+
LX
A ntiS hootThrough
Control Lo gic
Therm al
P rotection
+
RE F
-
Q3
PW M/P FM
Control
Zero C ross
Com parator
REF
+
+
G ND
PFM
C om pa rator
PIN DESCRIPTIONS
PIN 1: VIN-
PIN 2: BP-
Supply Voltage Input ranging from
+2.5V to +6.5V. Bypass with a
22µF capacitor.
Supply Bypass Pin internally
connecting to VIN. Bypass with a
0.1µF capacitor.
PIN 3: SHDN - Active-Low,
Shutdown-Control
Input reducing supply current to
0.1µA in shutdown mode.
PIN 4: FBFeedback Input.
PIN 5: RTFrequency
Adjustable
Pin
connecting to GND through a
resistor to increase frequency.
(Refer to Fig. 15)
PIN 6: SYNC/MODEOscillator Sync and Low-Noise,
Mode-Control Input.
SYNC/MODE = VIN (Forced
PWM Mode)
SYNC/MODE = GND (PWM/PFM
Mode)
An
external
clock
signal
connecting to this pin allows LX
switching synchronization.
PIN 7: GNDGround.
PIN 8: LX-
Inductor connecting to the Drains
of the Internal Power MOSFETs
9
AIC1555
APPLICATION INFORMATIONS
block. Similarly, when Q3 is on, Q2 will turn off.
Introduction
AIC1555 is a low-noise, pulse-width-modulated
(PWM), DC-DC step-down converter. It features
an internal synchronous rectifier, which eliminates
external Schottky diode. AIC1555 is suitable for Lilon battery applications, or can be used at 3V or
5V fixed input voltage. It operates in one of
following four modes.
AIC1555 provides current limit function by using a
5Ω resistor. When Q1 turns on, current follows
through the 5Ω resistor. And current amplifier
senses the voltage, which crosses the resistor,
and amplifies it. When the sensed voltage gets
bigger than reference voltage, output current will
be clamped a maximum level.
AIC1555 provides the thermal protection. When
(1) Forced PWM mode operates at a fixed
the action is happened then the control logic shuts
frequency regardless of the load.
the device off.
(2) Synchronizable PWM mode allows the
synchronization
switching
by
frequency
using
an
external
with
a
minimum
PWM/PFM Function
When connecting SYNC/MODE pin to VIN, the
harmonics.
is
forced
into
PWM
(3) PWM/PFM Mode extends battery life by
device
Modulated)
mode
with
constant
switching to a PFM pulse-skipping mode
Advantage
under light loads.
reducing noise without complex post-filter. But its
of
constant
(Pulse-Width-
frequency
frequency.
is
easily
(4) Shutdown mode sets device to standby,
disadvantage is low efficiency at light loading.
reducing supply current to 0.1µA or under.
Therefore, AIC1555 provides a function to solve
Continuous output current of AIC1555 can be
upward to 700mA and output voltage can be
adjusted from 0.75V to VIN with an input range
from 2.5V to 6.5V by a voltage divider. AIC1555
also features high efficiency, low dropout voltage,
and a 0.75V reference with ±2.5% accuracy. It is
available in a space-saving 8-pin MSOP package.
to GND, device is able to get into PWM/PFM
(Pulse-Frequency-Modulated) modes. Under a
light loading condition, the device turns to PFM
mode, which results in a higher efficiency. PWM
mode is on when heavy loading applies and the
noise is reduced.
Frequency Synchronization
Operation
When power on, control logic block detects
SYNC/MODE pin connecting to VIN or GND to
determine operation function and gives a signal to
PWM/PFM control block to determine the proper
comparator (ref. Block Diagram). AIC1555 works
with an internal synchronous rectifier
this problem. When connecting SYNC/MODE pin
- Q3,
to
Connecting
an
external
clock
signal
to
SNYC/MODE pin can control switching frequency.
The acceptable range is from 500kHz to 1MHz.
This mode exhibits low output ripple as well as low
audio noise and reduces RF interference while
providing reasonable low current efficiency.
increase efficiency. When control logic block turns
Q2 on, Q3 will turn off through anti-short-through
10
AIC1555
voltage, the converter continuously turns Q2 on. In
V
V
OUT = OUT
(2)
2 × Ma 2 × 0.27
Note that output voltage can be defined according
this mode, the output voltage is equal to the input
to user’s requirement to get a suitable inductor
voltage minus the voltage, which is the drop
value.
100% Duty Cycle Operation
When the input voltage approaches the output
L1 >
across Q2.
If input voltage is very close to output voltage, the
Output Capacitor
switching mode goes from pure PWM mode to
The selection of output capacitor depends on the
100% duty cycle operation. During this transient
suitable ripple voltage. Lower ripple voltage
state mentioned above, large output ripple voltage
corresponds to lower ESR (Equivalent Series
will appear on output terminal.
Resistor) of output capacitor. Typically, once the
ESR is satisfied with the ripple voltage, the value
of capacitor is adequate for filtering. The formula
Components Selection
Inductor
The inductor selection depends on the operating
frequency of AIC1555. The internal switching
of ripple voltage is as below:

1 

∆VOUT = ∆IL  ESR +
8 fC OUT 

(3)
external
Besides, in buck converter architecture frequency
synchronized frequency ranges from 500KHz to
stands at 1/ (LC) when a double pole formed by
1MHz. A higher frequency allows the uses of
the inductor and output capcitor occurs. This will
smaller inductor and capacitor values. But, higher
reduce phase margin of circuit so that the stability
frequency results lower efficiency due to the
gets
internal switching loss.
capacitor that is parallel with R1 can be added to
The ripple current ∆IL interrelates with the inductor
reduce output ripple voltage and increase circuit
value. A lower inductor value gets a higher ripple
stability. The output capacitor can be calculated as
current. Besides, a higher VIN or VOUT can also
the following formula.
frequency
is
500KHz,
and
the
get the same result. The inductor value can be
calculated as the following formula.


V
1
1 − OUT 
L=
V
(f )(∆IL ) OUT  VIN 
√
weakened.
1
L1 × C
≅
O
Therefore,
1
R1 × CF
a
feedforward
(4)
(1)
For more reduction in the ripple voltage, a 12pF
Users can define the acceptable ∆IL to gain a
ceramic capacitor, which is parallel with output
suitable inductor value.
capacitor, is used.
Since AIC1555 can be used in ceramic capacitor
External Schottky Diode
application, the component selection will be
AIC1555 has an internal synchronous rectifier,
different from the one for the application above.
instead of Schottky diode in buck converter.
AIC1555 has a built-in slope compensation, which
However, a blank time, which is an interval when
acitvates when duty cycle is larger than 0.45. The
μs, has to be larger than half of
both of main switch, Q2, and synchronous rectifier,
slope Ma, 0.27V/
Q3, are off; occurs at each switching cycle. At the
M2. M2 is equal to output voltage divided by L1.
moment, AIC1555 has a decreasing efficiency.
The formula of inductor is shown as below:
Therefore, an external Schottky diode is needed to
reinforce the efficiency.
11
AIC1555
Since the diode conducts during the off time, the
close as possible to each other to reduce the
peak current and voltage of converter is not
input ripple voltage.
allowed to exceed the diode ratings. The ratings of
diode can be calculated by the following formulas:
VD,MAX( OFF ) = VIN
ID,MAX(ON) = IOUT,MAX +
2. The output loop, which is consisted of
inductor, Schottky diode and output capacitor,
(5)
∆IL
2
(6)
should be kept as small as possible.
3. The routes with large current should be kept
short and wide.
4. Logically the large current on the converter,
ID,AVG( ON)
= IOUT − IIN = IOUT − D × IOUT
= (1 − D) × IOUT
when AIC1555 is on or off, should flow at the
(7)
same direction.
5. The FB pin should connect to feedback
Adjustable Output Voltage
AIC1555 appears a 0.75V reference voltage at FB
resistors directly. And the route should be
pin. Output voltage, ranging from 0.75V to VIN,
away from the noise source, such as inductor
of LX line.
can be set by connecting two external resistors,
R1 and R2. VOUT can be calculated as:
R1
VOUT = 0.75 V × (1 +
)
R2
6. Grounding all components at the same point
may effectively reduce the occurrence of loop.
(8)
A stability ground plane is very important for
Applying a 12pF capacitor parallel with R1 can
gaining higher efficiency. When a ground
prevent stray pickup. They should sit as close to
plane is cut apart, it may cause disturbed
AIC1555 as possible. But load transient response
signal and noise. If possible, two or three
is degraded by this capacitor.
through-holes can ensure the stability of
grounding.
Over Current Protection
Example
The current limiter circuit monitors the current
Here are two examples to prove the components
flowing through the P-channel MOS connected to
selector guide above.
the Lx pin, and features a constant-current type
current limit mode. If the inductor current does not
1. Tantalum capacitors application:
exceed the current limit, the high-side MOSFET
Assume AIC1555 is used for mobile phone
turns on normally. When the driver current is
application, which uses 1-cell Li-ion battery with
greater than a specific level, the constant-current
2.7V to 4.2V input voltage for power source. The
type current limit function operates to turn off the
required load current is 700mA, and the output
pulses from the Lx pin at any switching cycle. This
voltage is 1.8V. Substituting VOUT=1.8V, VIN=4.2V,
features a constant-current type over current
∆I=250mA, and f=500KHz to equation (1)
protection
L=
Layout Consideration
To ensure a proper operation of AIC1555, the
following points should be given attention to:
1. Input capacitor and Vin should be placed as
1.8 V
1.8 V 

1 −
 = 8.23µH
500KHz × 250mA 
4.2V 
Therefore, 10µH is proper for the inductor. And the
inductor of series number SLF6025-100M1R0
from
TDK
with
57.3mΩ
series
resistor
is
recommended for the best efficiency.
12
AIC1555
For output capacitor, the ESR is more important
Of the same AIC1555 application above, except
than
for ceramic capacitor used, Co, R1, and R2 can
its
capacity.
Assuming
ripple
voltage
∆V=100mV, then the ESR can be calculated as:
∆V 100mV
ESR=
=
= 0.4Ω
∆I
250mA
be calculated as following formulas. And the same
Therefore, a 33µF/10V capacitor, MCM series
VOUT is substituted by 1.8V in equation (2) as
values of load current and output voltage at
700mA and 1.8V respectively are used.
from NIPPON, is recommend.
Schottky selection is calculated as following.
VD,MAX( OFF ) = VIN = 4.2V
∆IL
2
250mA
= 800mA +
2
ID,MAX(ON) = IOUT,MAX +
= 925mA
L1 >
V
OUT = 1.8 = 3.33 µH
0.54
0.54
Let L1 = 6.8µH, and choose CF = 12pF, R1 =
820kΩ.
Co calculated by the following formula can
improve circuit stability.
1
ID,avg(ON) = (1 − D ) × IOUT
1 .8
= (1 −
) × 800mA
4 .2
= 457.14mA
According the datas above, the Schottky diode,
SS12, from GS is recommend.
For feedback resistors, choose R2=390kΩ and R1
can be calculated as follow:
≅
L1 × C
O
1
R1 × CF
Therefore,
C
O
=
(R1 × CF )2 = (820k × 12pF)2
L1
= 12 µF
Say, CO is 22µF. Then, R2 can be decided by
equation (8) as
R1
VOUT
1.8
−1=
− 1 = 1.4
V
0.75
ref
 1.8V

R1 = 
− 1 × 390kΩ = 546kΩ ; use 560kΩ
 0.75

R2
Fig. 22 and Fig.23 shows the application circuit of
So, R2 = 560kΩ.
AIC1555.
6.8µ.
=
Note: Schottky diode, SS12 from GS, is still
required in this application.
2. Ceramic capacitors application:
13
AIC1555
VIN= 2.5V to 6.5V
1
BP
+
CIN
10µF
CBP
0.1µF
2 BP
3
SHDN
4
FB
10µH
D1
SS12
GND 7
**
SYNC/ 6
MODE
5
RT
VOUT = 1.8V
L1
8
LX
VIN
Optional
CF
R1
560K
10P
+
AIC1555
*CO1
*CO2
4.7µF
33µF
R2
390K
* Note: CO1 can be omitted if CO2 is 10µF Ceramic
CIN: NIPPON 10µF/10V Tantalum capacitor
** Note: Efficiency can boost 2% to 4% if D1 is connected.
CO1: NIPPON 33µF/6V Tantalum capacitor
L: TDK SLF6025-100M1R0
D1: GS SS12
Fig. 23 AIC1555 Application Circuit (Tantalum capacitor application)
VIN= 2.5V to 6.5V
1
BP
CIN
22µF
CBP
0.1µF
LX
2 BP
3
SHDN
4
FB
GND 7
SYNC/ 6
MODE
RT
5
VOUT = 1.8V
L1
8
VIN
*
6.8µH
D1
SS12
Optional
CF
R1
820K
12pF
AIC1555
CO
R2
560K
22µF
CIN: TAIYO YUDEN LMK316F226ZL-T Ceramic capacitor
CO: TAIYO YUDEN LMK316F226ZL-T Ceramic capacitor
L1: TDK SLF6025-6R8M1R3
D1: GS SS12
* Note: Efficiency can boost 2% to 4% if D1 is connected.
Fig. 24 AIC1555 Application Circuit (Ceramic capacitor application)
14
AIC1555
PHYSICAL DIMENSIONS
MSOP 8 (unit: mm)
D
1E
A A
e
S
Y
M
B
O
L
E
SEE VIEW B
2A
1A
MIN.
WITH PLATING
52
.0
MAX.
1.10
A1
0.05
0.15
A2
0.75
0.95
b
0.25
0.40
c
0.13
0.23
D
2.90
3.10
E
E1
b
L
MILLIMETERS
A
A
VIEW B
MSOP-8
BASE METAL
SECTION A-A
GAUGE PLANE
SEATING PLANE
c
4.90 BSC
2.90
e
3.10
0.65 BSC
L
0.40
0.70
q
0°
6°
θ
Note: 1. Refer to JEDEC MO-187AA.
2. Dimension "D" does not include mold flash, protrusions
or gate burrs. Mold flash, protrusion or gate burrs shall not
exceed 6 mil per side .
3. Dimension "E1" does not include inter-lead flash or protrusions.
4. Controlling dimension is millimeter, converted inch
dimensions are not necessarily exact.
Note:
Information provided by AIC is believed to be accurate and reliable. However, we cannot assume responsibility for use of any
circuitry other than circuitry entirely embodied in an AIC product; nor for any infringement of patents or other rights of third
parties that may result from its use. We reserve the right to change the circuitry and specifications without notice.
Life Support Policy: AIC does not authorize any AIC product for use in life support devices and/or systems. Life support devices
or systems are devices or systems which, (I) are intended for surgical implant into the body or (ii) support or sustain life, and
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 to the user.
15
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