SS6620/21/2
High Efficiency Synchronous Step-Up DC/DC Converter
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FEATURES
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DESCRIPTION
The SS6620/21/22 are high-efficiency step-
up DC/DC converters, with start-up voltage as
low as 0.8V and operating with an input voltage
down to 0.7V. Consuming only 20µA of quies-
cent current, these devices offer a built-in syn-
chronous rectifier that reduces size and cost by
eliminating the need for an external Schottky
diode, improving overall efficiency by minimiz-
ing losses.
The switching frequency depends on the load
and the input voltage and can range up to
500KHz. The peak current of the internal switch
is fixed at 0.8A (SS6620), at 0.45A
(SS6621), or is selectable (SS6622) for
design flexibility. Ripple does not exceed the
product of the switch current limit and the filter
capacitor equivalent-series-resistance (ESR).
The SS6622 also features a circuit that
eliminates noise caused by inductor ringing.
High efficiency of 93% (V
IN
=2.4V, V
OUT
=3.3V,
I
OUT
=200mA).
Quiescent supply current of 20µA.
Power-saving shutdown mode (0.1µA typical).
Internal synchronous rectifier (no external diode )
Selectable current limit for reduced ripple
(SS6622).
Low noise, anti-ringing feature (SS6622)
On-chip low-battery detector.
Low-battery hysteresis
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APPLICATIONS
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Palmtop & notebook computers.
PDAs
Wireless phones
Pocket organizers.
Cameras.
1 to 2-cell hand-held devices
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TYPICAL APPLICATION CIRCUIT
V
IN
+
100µF
OFF
SHDN
SS6620
SS6621
SS6622
LBI
REF
0.1µF
FB
LBO
LX
OUT
22µH
Output 3.3V, or
Adj. (1.8V to 4.0V)
up to 300mA
ON
+
220µF
Low-Battery
Detect In
LBO
GND
FB
Low-Battery
Detect Out
Rev.2.01 6/06/2003
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SS6620/21/2
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ORDERING INFORMATION
SS6620CX XX
SS6621CX XX
SS6622CX XX
PACKING TYPE
TR: TAPE & REEL
PACKAGING TYPE
O: MSOP8 (for SS6620/1)
O: MSOP10 (for SS6622)
PIN CONFIGURATION
(MSOP8)
FB 1
LBI 2
LBO 3
REF 4
TOP VIEW
8
OUT
LX
GND
SHDN
SS6620
SS6621
7
6
5
(MSOP10)
FB 1
TOP VIEW
10
OUT
Example: SS6620COTR
à
In MSOP8 Package in Tape & Reel
LBI 2
LBO 3
CLSEL 4
REF 5
9 LX
SS6622
8 GND
7 BATT
6 SHDN
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ABSOLUTE MAXIMUM RATINGS
Supply Voltage (OUT to GND)
Switch Voltage (LX to GND)
Battery Voltage (Batt to GND)
SHDN , LBO to GND
LBI, REF, FB, CLSEL to GND
Switch Current (LX)
Output Current (OUT)
Operating Temperature Range
Storage Temperature Range
8.0V
V
OUT
+ 0.3V
6.0V
6.0V
V
OUT
+0.3V
-1.5A to +1.5A
-1.5A to +1.5A
-40°C ~ +85°C
-65°C ~150°C
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TEST CIRCUIT
Refer to Typical Application Circuit.
Rev.2.01 6/06/2003
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SS6620/21/2
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ELECTRICAL CHARACTERISTICS
(V
T
A
=25°C, unless otherwise specified.)
BATT
=2.0V,
V
OUT
=3.3V (FB=V
OUT
), R
L
=∝,
PARAMETER
Minimum Input Voltage
Operating Voltage
Start-Up Voltage
Start-Up Voltage Tempco
Output Voltage Range
Output Voltage
TEST CONDITIONS
MIN.
TYP.
0.7
MAX.
UNIT
V
1.1
R
L
=3KΩ (Note1)
0.8
-2
1.8
FB = V
OUT
3.17
300
3.3
400
4.0
1.1
V
V
mV/°C
4.0
3.43
V
SS6620
SS6622
Steady State Output Current FB=OUT
(CLSEL=OUT)
(
V
OUT
=3.3V) SS6621
(Note 2)
SS6622
(CLSEL=GND)
Reference Voltage
Reference Voltage Tempco
Reference Load Regulation
Reference Line Regulation
FB , LBI Input Threshold
Internal Switch On-Resistance
I
LX
= 100mA
SS6620,SS6622(CLSEL =
OUT)
LX Switch Current Limit
SS6621,SS6622(CLSEL =
GND)
LX Leakage Current
Operating Current into OUT
(Note 3)
Shutdown Current into OUT
Efficiency
V
OUT
= 2V ,I
LOAD
= 1mA
LX Switch On-Time
LX Switch Off-Time
FB Input Current
Rev.2.01 6/06/2003
mA
150
1.199
220
1.23
0.024
1.261
V
mV/°C
30
10
1.261
mV
mV/V
V
Ω
1.0
A
0.3
0.45
0.6
µA
µA
I
REF
= 0
I
REF
= 0 to 100
µA
V
OUT
= 1.8V to 4V
1.199
10
5
1.23
0.3
0.6
0.8
V
LX
=0V, 4V; V
OUT
=4V
V
FB
= 1.4V , V
OUT
= 3.3V
0.05
20
1
35
SHDN = GND
V
OUT
= 3.3V ,I
LOAD
= 200mA
0.1
90
1
µA
%
85
2
0.6
4
0.9
0.03
7
1.3
50
µs
µs
nA
V
FB
=1V , V
OUT
= 3.3V
V
FB
=1V , V
OUT
= 3.3V
V
FB
= 1.4V
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SS6620/21/2
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ELECTRICAL CHARACTERISTICS
(Continued)
PARAMETER
LBI Input Current
CLSEL Input Current
SHDN
Input Current
LBO
Low Output Voltage
LBO
Off Leakage Current
TEST CONDITIONS
V
LBI
= 1.4V
SS6622 , CLSEL = OUT
V
SHDN
= 0 or V
OUT
V
LBI
= 0, I
SINK
= 1mA
V
LBO
= 5.5V, V
LBI
= 5.5V
MIN.
TYP.
1
1.4
0.07
0.2
0.07
50
MAX.
50
3
50
0.4
1
UNIT
nA
µA
nA
µA
LBI Hystereisis
Damping Switch Resistance
SHDN
Input Voltage
mV
100
0.2V
OUT
V
Ω
SS6622, V
BATT
= 2V
50
0.8V
OUT
0.2V
OUT
CLSEL Input Voltage
0.8V
OUT
V
Note 1:
Start-up voltage operation is guaranteed without the addition of an external Schottky diode between the in-
put 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.
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TYPICAL PERFORMANCE CHARACTERISTICS
100
90
80
160
Input Battery Current (
µ
A)
140
120
100
80
60
40
20
0
Efficiency (%)
70
60
50
40
30
20
10
0
0.01
0.1
1
V
IN
=2.4V
V
IN
=1.2V
I_limit=0.8A , V
OUT
=3.3V
I_limit=0.45A , V
OUT
=3.3V
0.0
0.5
1.0
1.5
2.0
2.5
3.0
10
100
1000
Loading (mA)
Input battery voltage (V)
Fig. 1 V
OUT
=3.3V
CLSEL=OUT (0.8A)
Fig. 2 No-Load Battery Current vs. Input Battery Voltage
Rev.2.01 6/06/2003
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SS6620/21/2
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100
90
TYPICAL PERFORMANCE CHARACTERISTICS
1.8
1.6
(Continued)
80
Start-up Voltage (V)
1.4
1.2
1.0
0.8
0.6
0.4
Efficiency (%)
V
IN
=2.4V
70
Without Diode
V
IN
=1.2V
60
With Diode
50
0.2
40
0.01
0.1
1
10
100
1000
0.0
0.01
0.1
1
10
100
Loading (mA)
Fig. 3 V
OUT
=3.3V CLSEL=GND (0.45A)
0.10
0.08
2.2
2.0
Load Current (mA)
Fig. 4 Start-up Voltage vs. Load Current
Shutdown Current (
µ
A)
0.06
0.04
0.02
0.00
-0.02
-0.04
-0.06
-0.08
-0.10
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Shutdown Threshold (V)
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Fig. 5
800
V
OUT
(V)
Shutdown Current vs. V
OUT
Output Voltage (V)
Fig. 6 Shutdown Threshold vs. Output Voltage
Maximum Output Current (mA)
700
600
V
OUT
=3.3V
CLSEL=OUT
LX pin waveform
500
400
300
200
V
OUT
AC Couple
CLSEL=GND
100
0
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
Inductor Current
V
IN
=2.4V
V
OUT
=3.3V
Input Voltage (V)
Fig. 7
Maximum Output Current vs. Input Voltage
Fig. 8
Heavy Load Waveform
Rev.2.01 6/06/2003
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