AIC AIC1622COTR

AIC1620/AIC1621/AIC1622
High Efficiency Synchronous Step-Up DC/DC
Converter
n DESCRIPTION
n FEATURES
High Efficiency 93% (V IN=2.4V, VOUT =3.3V,
IOUT =200mA).
The AIC1620/AIC1621/AIC1622 are high effi-
l
20µA Quiescent Supply Current.
voltage is as low as 0.8V and operate with an
l
Power-Saving Shutdown Mode (0.1µA typical).
input voltage down to 0.7V. Consuming only
l
Internal Synchronous Rectifier ( no external
diode )
20µA of quiescent current. These devices offer
l
Selectable Current Limit for Reduced Ripple
( AIC1622 ).
size and cost by eliminating the need for an ex-
l
Low Noise , Anti-Ringing Feature ( AIC1622 )
ternal Schottky diode and improves overall effi-
l
On-Chip Low Battery Detector.
ciency by minimizing losses.
l
Low Battery Hysteresis
The switching frequency depends on the load
l
ciency step up DC-DC converter. The start-up
a built-in synchronous rectifier that reduces
and the input voltage can range up to 500KHz.
n APPLICATIONS
The peak current of the internal switch is fixed
l
Palmtop & Notebook Computers.
at 0.8A (AIC1620), at 0.45A (AIC1621), or is
l
PDAs
selectable (AIC1622) for design flexibility. Rip-
l
Wireless Phones
ple does not exceed the product of the switch
l
Pocket Organizers.
current limit and the filter capacitor equivalent
l
Cameras.
series resistance (ESR). The AIC1622 also fea-
l
1 to 2-Cell Hand-Held Devices
tures a circuit that eliminates noise due to inductor ringing.
n TYPICAL APPLICATION CIRCUIT
VIN
ON
+
100µF
OFF
22µH
LX
SHDN
Low-Battery
Detect In
LBI
AIC1620
AIC1621
AIC1622
REF
OUT
LBO
FB
LBO
GNDFB
Output 3.3V, or
Adj. (1.8V to 4.0V)
up to 300mA
+
220µF
Low-Battery
Detect Out
0.1µF
Analog Integrations Corporation
4F, 9 Industry E. 9th Rd, Science-Based Industrial Park, Hsinchu, Taiwan
TEL: 886-3-5772500
FAX: 886-3-5772510
www.analog.com.tw
DS-1620-00 032502
1
AIC1620/AIC1621/AIC1622
n ORDERING INFORMATION
AIC1620CX XX
AIC1621C X XX
AIC1622C X XX
PIN CONFIGURATION
(MSOP8)
PACKING TYPE
TR: TAPE & REEL
PACKAGING TYPE
O: MSOP8 (for AIC1620/1)
O: MSOP10 (for AIC1622)
TOP VIEW
FB 1
8
OUT
LBI 2
7
LX
6
GND
5
SHDN
LBO 3
AIC1620
AIC1621
REF 4
TOP VIEW
(MSOP10)
FB 1
Example: AIC1620COTR
à In MSO8 Package & Taping &
Reel Packing Type
10 OUT
LBI 2
LBO 3
9 LX
AIC1622
8
GND
CLSEL 4
7
BATT
REF 5
6
SHDN
n ABSOLUTE MAXIMUM RATINGS
Supply Voltage (OUT to GND)
Switch Voltage (LX to GND)
8.0V
VOUT + 0.3V
Battery Voltage (Batt to GND)
6.0V
SHDN , LBO to GND
6.0V
LBI, REF, FB, CLSEL to GND
VOUT +0.3V
Switch Current (LX)
-1.5A to +1.5A
Output Current (OUT)
-1.5A to +1.5A
Operating Temperature Range
-40°C ~ +85°C
Storage Temperature Range
-65°C ~150°C
n TEST CIRCUIT
Refer to Typical Application Circuit.
2
AIC1620/AIC1621/AIC1622
n ELECTRICAL CHARACTERISTICS (V
BATT=2.0V,
VOUT=3.3V (FB=VOUT), RL=∝,
TA=25°C, unless otherwise specified.)
PARAMETER
TEST CONDITIONS
MIN.
Minimum Input Voltage
1.1
RL=3KΩ (Note1)
0.8
Start-Up Voltage Tempco
1.8
FB = VOUT
AIC1620
AIC1622 (CLSEL=OUT)
Steady State Output Current
FB=OUT
(Note 2)
( VOUT =3.3V) AIC1621
AIC1622 (CLSEL=GND)
Reference Voltage
IREF= 0
UNIT
V
4.0
V
1.1
V
-2
Output Voltage Range
Output Voltage
MAX.
0.7
Operating Voltage
Start-Up Voltage
TYP.
mV/°C
4.0
3.17
3.3
300
400
3.43
V
mA
150
220
1.199
1.23
Reference Voltage Tempco
1.261
0.024
V
mV/°C
Reference Load Regulation
IREF = 0 to 100 µA
10
30
mV
Reference Line Regulation
VOUT = 1.8V to 4V
5
10
mV/V
1.23
1.261
V
FB , LBI Input Threshold
Internal switch On-Resistance
1.199
ILX = 100mA
Ω
0.3
AIC1620,AIC1622(CLSEL = OUT)
0.6
0.8
1.0
AIC1621,AIC1622(CLSEL = GND)
0.3
0.45
0.6
0.05
1
µA
LX Switch Current Limit
A
LX Leakage Current
VLX=0V, 4V; VOUT =4V
Operating Current into OUT
VFB = 1.4V , VOUT = 3.3V
20
35
µA
SHDN = GND
0.1
1
µA
VOUT = 3.3V ,ILOAD = 200mA
90
VOUT = 2V ,ILOAD = 1mA
85
(Note 3)
Shutdown Current into OUT
Efficiency
%
LX Switch On-Time
VFB =1V , VOUT = 3.3V
2
4
7
µS
LX Switch Off-Time
VFB =1V , VOUT = 3.3V
0.6
0.9
1.3
µS
FB Input Current
VFB = 1.4V
0.03
50
nA
3
AIC1620/AIC1621/AIC1622
n ELECTRICAL CHARACTERISTICS (Continued)
PARAMETER
TEST CONDITIONS
MIN.
TYP.
MAX.
UNIT
1
50
nA
LBI Input Current
VLBI = 1.4V
CLSEL Input Current
AIC1622 , CLSEL = OUT
1.4
3
µA
SHDN Input Current
V SHDN = 0 or VOUT
0.07
50
nA
LBO Low Output Voltage
VLBI = 0, ISINK = 1mA
0.2
0.4
µA
LBO Off Leakage Current
V LBO = 5.5V, VLBI = 5.5V
0.07
1
LBI Hystereisis
50
Damping Switch Resistance
AIC1622, VBATT = 2V
mV
50
100
Ω
0.2V OUT
SHDN Input Voltage
V
0.8V OUT
0.2V OUT
CLSEL Input Voltage
V
0.8V OUT
Note 1: Start-up voltage operation is guaranteed without the addition of an external Schottky diode between the input and output.
Note 2: Steady-state output current indicates that the device maintains output voltage regulation under load.
Note 3: Device is bootstrapped (power to the IC comes from OUT). This correlates directly with the actual battery
supply.
n TYPICAL PERFORMANCE CHARACTERISTICS
100
160
90
Input Battery Current (µA)
140
Efficiency (%)
80
120
V IN=2.4V
70
100
VIN=1.2V
60
50
40
30
20
80
I_limit=0.8A , VOUT=3.3V
60
40
I_limit=0.45A , V OUT=3.3V
20
10
0
0.01
0.1
1
10
100
1000
0 0.0
VOUT =3.3V
CLSEL=OUT (0.8A)
1.0
1.5
2.0
2.5
3.0
Input battery voltage (V)
Loading (mA)
Fig. 1
0.5
Fig. 2
No-Load Battery Current vs. Input Battery Voltage
4
AIC1620/AIC1621/AIC1622
n TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
1.8
100
1.6
Start-up Voltage (V)
Efficiency (%)
90
80
V IN =2.4V
70
V IN =1.2V
60
1.4
1.2
1.0
Without Diode
0.8
0.6
With Diode
0.4
50
0.2
0.1
1
10
100
0.0
0.01
1000
0.1
1
10
100
Loading (mA)
Load Current (mA)
Fig. 3 VOUT=3.3V CLSEL=GND (0.45A)
Fig. 4 Start-up Voltage vs. Load Current
0.10
2.2
0.08
2.0
Shutdown Threshold (V)
Shutdown Current (µA)
40
0.01
0.06
0.04
0.02
0.00
-0.02
-0.04
-0.06
-0.08
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
-0.10
1.0
1.5
2.0
Fig. 5
2.5
3.0
3.5
4.0
VOUT (V)
Shutdown Current vs. VOUT
0.0
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Output Voltage (V)
Fig. 6
Shutdown Threshold vs. Output Voltage
Maximum Output Current (mA)
800
LX pin waveform
VOUT=3.3V
700
600
CLSEL=OUT
VOUT AC Couple
500
400
300
200
CLSEL=GND
100
Inductor Current
VIN =2.4V
VOUT =3.3V
0
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
Input Voltage (V)
Fig. 7
Maximum Output Current vs. Input Voltage
Fig. 8 Heavy Load Waveform
5
AIC1620/AIC1621/AIC1622
n TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
Fig. 9
VIN =2.4V
VOUT=3.3V
Without Damping Ringing Function
Fig. 10 With Damping Ringing Function
∆ IOUT=200mA
VOUT AC Couple
Fig. 11 Load Transient Response
6
AIC1620/AIC1621/AIC1622
n BLOCK DIAGRAM
SHDN
CLSEL
OUT
Minimum Off-Time
+
Q1
One Shot
L
1
47µF
Q
R
C3
220µF
R1
BATT 200Ω
LX
Q2
F/F
S
Damping
Switch
Q3
OUT
0.1µF
VIN
+
C1
100µF
GND
One Shot
Maximum On-Time
+
Mirror
FB
+
+
LBO
Reference Voltage
REF
C4
0.1µF
LBI
n PIN DESCRIPTIONS
AIC1620/ AIC1621
PIN 1: FBConnect to OUT for +3.3V output.
Use a resistor network to set the
output voltage from +1.8V to +4.0V.
PIN 2: LBILow-battery comparator input. n
I ternally set to trip at +1.23V.
PIN 3: LBO- Open-drain low battery comparator
output. Output is low when VLBI is
<1.23V. LBO is high impedance
during shutdown.
PIN 4: REF-
1.23V reference voltage. Bypass
with a 0.1µF capacitor.
PIN 5: SHDN- Shutdown input. High=operating,
low=shutdown.
PIN 6: GND- Ground
PIN 7: LXN-channel and P-channel power
MOSFET drain.
PIN 8: OUT- Power output. OUT provides bootstrap power to the IC.
7
AIC1620/AIC1621/AIC1622
AIC1622
PIN 1: FB-
Connect to OUT for +3.3V output.
Use a resistor network to set the
output voltage from +1.8V to +4.0V.
PIN 2: LBILow-Battery comparator input. Internally set to trip at +1.23V.
PIN 3: LBO- Open-drain low battery comparator
output. Output is low when VLBI is
<1.23V. LBO is high impedance
during shutdown.
PIN 4: CLSEL- Current-limit selects input. CLSEL=
OUT sets the current limit to 0.8A.
CLSEL=GND sets the current limit
to 0.45A.
PIN 5: REF-
1.23V reference voltage. Bypass
with a 0.1µF capacitor.
PIN 6: SHDN- Shutdown input. High=operating,
low=shutdown.
PIN 7: BATT- Battery input and damping switch
connection. If damping switch is
unused, leave BATT unconnected.
PIN 8: GND- Ground.
PIN 9: LXN-channel and P-channel power
MOSFET drain.
PIN 10: OUT- Power output. OUT provides
bootstrap power to the IC.
n APPLICATION INFORMATION
Overview
The AIC1620/AIC1621/AIC1622 series are high efficiency, step-up DC-DC converters, designed to feature a built-in synchronous rectifier, which reduces
size and cost by eliminating the need for an external
Schottky diode. The start-up voltage is as low as
0.9V and operate with an input voltage down to 0.7V.
Quiescent supply current is only 20µA. In addition,
the AIC1622 feature a circuit that eliminates inductor
ring to reduce noise. The internal P-MOSFET onresistance is typically 0.3Ω to improve overall efficiency by minimizing AC losses. The current limit of
the AIC1620 and AIC1621 are 0.8A and 0.45A respectively. The AIC1622 offers a selectable current
limit(0.45A or 0.8A). The lower current limit allows the
use of a physically smaller inductor in spacesensitive applications.
PFM Control Scheme
The key feature of the AIC1620 series is a unique
minimum-off-time, current-limited, pulse-frequencymodulation (PFM) control scheme (see BLOCK
DIAGRAM) with the ultra-low quiescent current . A
constant-peak-current limit in the switching allows the
inductor current to vary between this peak limit and
some lesser value. The peak current of the internal NMOSFET power switch can be fixed at 0.8A, 0.45A or
is selectable. Besides, the ripple voltage dose not
exceed the product of the peak current limit and the
filter capacitor equivalent series resistance (ESR).
The switch frequency depends on the loading condition and input voltage, and can range up to 500KHz.
The switching frequency is governed by a pair of oneshots that set a minimum off-time (1µS) and a maximum on-time (4µS).
8
AIC1620/AIC1621/AIC1622
Synchronous Rectification
BATT/Damping Switch
Using the internal synchronous rectifier eliminates the
The AIC1622 is designed with an internal damping
need for an external Schottky diode. Therefore, the
switch (Fig. 15) to reduce ringing at LX. The damping
cost and board space is reduced. During the cycle of
switch supply a path to quickly dissipate the energy
off-time, the P-MOSFET turns on and shunts the N-
stored in inductor and reduces the ringing at LX.
MOSFET.
turn-on
Damping LX ringing dose not reduce VOUT ripple, but
resistance of MOSFET, the synchronous rectifier sig-
dose reduce EMI. R1=200Ω works well for most ap-
nificantly improves efficiency without the addition of
plication while reducing efficiency by only 1%. Larger
an external component. Thus, the conversion efficien-
R1 value provide less damping, but less impact on ef-
cy can be as high as 93%.
ficiency. In principle, lower value of R1 is needed to
Due
to
the
low
fully damp LX when the VOUT /VIN ratio is high.
Reference Voltage
The reference voltage (REF) is nominally 1.23V for
Selecting the Output Voltage
excellent T.C. performance. In addition, REF pin can
VOUT can be simply set to 3.3V by connecting the FB
source up to 100µA to external circuit with good load
pin to OUT due to internal resistor divider (Fig. 16). In
regulation (<10mV). A bypass capacitor of 0.1µF is
order to adjust the output voltage, a resistor divider is
required for proper operation and good performance
connected to VOUT, FB, GND (Fig. 17). Use the following equation to calculate:
Shutdown
The whole circuit is shutdown when VSHDN is low.
During shutdown mode, the current can flow from the
R5=R6 [(V OUT / VREF )-1]
Where VREF =1.23V and VOUT may range from 1.8V to
4V.
battery to the output due to body diode of the PMOSFET. VOUT falls to approximately Vin-0.6V and
LX remains high impedance. The capacitance and
Low-Battery Detection
load at OUT determine the rate at which VOUT decays.
The AIC1620 series contain an on-chip comparator
Shutdown can be pulled as high as 6V. Regardless of
with 50mV internal hysteresis (REF, REF+50mV) for
the voltage at OUT.
low battery detection. If the voltage at LBI falls below
the internal reference voltage. LBO ( an open-drain
output) sinks current to GND.
Current Limit Select Pin
The AIC1622 series allows a selectable inductor current limit of either 0.45A or 0.8A. This allows flexibility
in designing for higher current or smaller applications.
CLSEL draws 1.4µA when connected to OUT.
9
AIC1620/AIC1621/AIC1622
Component Selection
be. A filter capacitor with low ESR is helpful to
1. Inductor Selection
the efficiency and steady state output current of
An inductor value of 22µH performs well in most
AIC1620 series. Therefore HERMEI capacitor LT
applications. The AIC1620 series also work with
series with 220µF/6.3V is recommended. A
inductors in the 10µH to 47µH range. An inductor
smaller capacitor (down to 10F with higher ESR)
with higher peak inductor current tends a higher
is acceptable for light loads or in applications that
output voltage ripple (IPEAK×output filter capacitor
can tolerate higher output ripple.
ESR). The inductor’s DC resistance significantly
affects efficiency. We can calculate the maximum
output current as follows:
VIN 
 VOUT − VIN
IOUT ( MAX) =
ILIM − t OFF 
VOUT 
2 ×L

3. PCB Layout and Grounding

 η

where IOUT(MAX)=maximum output current in
amps
Since AIC1622’s switching frequency can range
up to 500kHz, it makes AIC1622 become very
sensitive. So careful printed circuit layout is m
i portant for minimizing ground bounce and noise.
IC’s OUT pin should be as clear as possible. And
the GND pin should be placed close to the ground
VIN=input voltage
plane. Keep the IC’s GND pin and the ground
L=inductor value in µH
leads of the input and output filter capacitors less
η=efficiency (typically 0.9)
than 0.2in (5mm) apart. In addition, keep all con-
tOFF=LX switch’off-time in µS
nection to the FB and LX pins as short as possi-
ILIM =0.45A or 0.8A
ble. In particular, when using external feedback
resistors, locate them as close to the FB as pos-
2. Capacitor Selection
sible. To maximize output power and efficiency
The output voltage ripple relates with the peak in-
and minimize output ripple voltage, use a ground
ductor current and the output capacitor ESR. Be-
plane and solder the IC’s GND directly to the
sides output ripple voltage, the output ripple cur-
ground plane. Following are the recommended
rent also needs to be concerned. The smaller the
layout diagrams.
capacitor ESR is, the higher the ripple current will
Figure 12. Top layer
Figure 13. Bottom layer
Figure 14. Placement
10
AIC1620/AIC1621/AIC1622
n APPLICATION EXAMPLES
VIN
VOUT
Q1
R1
200Ω
OUT DAMPING
SWITCH
Q3
BATT
R1
200Ω
L
22µH
VIN
LX
BATT
(AIC1622)
R3
LBI
C1
100µF
OUT
CLSEL
(AIC1622)
VOUT
C2
0.1µF
C3
220µF
SHDN
LX
R4
L1
Q2
R2
100KΩ
REF
22µ H
0.1µ F
LBO
C4
GND
AIC1622
FB
LOW BATTERY
OUTPUT
AIC1620
AIC1621
AIC1622
GND
Fig. 15. Simplified Damping Switch Diagram
Fig. 16 VOUT = 3.3V Application Circuit.
VIN
R1
200Ω
L
22µH
LX
BATT
(AIC1622)
R3
LBI
VOUT
OUT
CLSEL
(AIC1622)
C2
0.1µF
SHDN
R4
0.1µF
C4
C1
100µF
100KΩ
R2
REF
C3
220µF
R5
LBO
GND
FB
AIC1620
AIC1621
AIC1622
LOW BATTERY
OUTPUT
R6
Fig. 17 An Adjustable Output Application Circuit
11
AIC1620/AIC1621/AIC1622
n PHYSICAL DIMENSION
l
8 LEAD MSOP (unit: mm)
D
E
E1
e
A2
SYMBOL
MIN
MAX
A1
--
0.20
A2
0.76
0.97
b
0.28
0.38
C
0.13
0.23
D
2.90
3.10
E
4.80
5.00
E1
2.90
3.10
e
L
0.40
0.66
SYMBOL
MIN
MAX
A1
--
0.20
A2
0.76
0.97
b
0.15
0.30
C
0.13
0.23
D
2.90
3.10
E
4.80
5.00
E1
2.90
3.10
A1
C
0.65
b
10 LEAD MSOP (unit: mm)
D
E
E1
e
A2
e
C
L
0.50
0.40
0.66
A1
l
L
b
L
12