SSC SS6639

SS6639
1-Cell, 3-Pin, Step-Up DC/DC Controller
n
n
FEATURES
GENERAL DESCRIPTION
•
•
Guaranteed start-up from less than 0.9 V.
High efficiency.
•
•
•
Low quiescent current.
Fewer external components needed.
Low ripple and low noise.
three external components are required to deliver a
Fixed output voltage: 2.7, 3.0V, 3.3V, and 5V.
Driver for external transistor.
Space-saving package: SOT-89 and TO-92.
load. The Pulse Frequency Modulation scheme offers
•
•
•
The SS6639 is a high efficiency step-up DC/DC
controller for applications using 1 to 4 battery cells. Only
fixed output voltage of 2.7, 3.0V, 3.3V, or 5V. The
SS6639 starts up from less than 0.9V input with a 1mA
optimized performance for applications with light output
loading and low input voltages. The output ripple and
noise are lower than with circuits operating in PSM
mode.
n
APPLICATIONS
The PFM control circuit operating up to 100 KHz
•
•
Pagers.
Cameras.
•
•
•
Wireless Microphones.
Pocket Organizers.
Battery Backup Suppliers.
•
Portable Instruments.
switching rate results in smaller passive components.
The space-saving SOT-89 and TO-92 packages make
the SS6639 an ideal choice of DC/DC controller for
space-conscious
applications,
such
as
pagers,
electronic cameras, and wireless microphones.
Using an external transistor driver pin (EXT), the
SS6639 is recommended for applications requiring
currents from several tens to several hundreds of
milliamperes.
n TYPICAL APPLICATION CIRCUIT
VIN
D1
VOUT
+
C1
47µF
L1
33µH
R1
*Q1
2SD1803
300
GS SS14
SS6639-27
SS6639-30
EXT SS6639-33
SS6639-50
C2
10nF
VOUT
+
C3
100µF
GND
*Q1: Sanyo 25D1803S-TC 60V/5A/20W
100mA Load Current Step-Up Converter
Rev.2.01 6/26/2003
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SS6639
n
ORDERING INFORMATION
SS6639-XXCXXX
PIN CONFIGURATION
PACKING TYPE
TR: TAPE & REEL
BG: BAG
SOT-89
TOP VIEW
1: GND
2: VOUT
3: EXT
PACKAGE TYPE
X: SOT-89
Z: TO-92
1
OUTPUT VOLTAGE
27: 2.7V
30: 3.0V
33: 3.3V
50: 5.0V
TO-92
TOP VIEW
1: GND
2: VOUT
3: EXT
EX: SS6639-27CXTR
à 2.7V Version, in SOT-89 Package in
2
3
1
2
3
Tape and Reel Packing
n ABSOLUTE MAXIMUM RATINGS
Supply Voltage (VOUT Pin) ……………….………………………………………………….12V
EXT pin Voltage ……………………………………………………..……….-0.3V to Vout+0.3V
EXT pin Current …………………………………………………..……………………….± 50mA
Operating Temperature Range
………………………………..……………….-40°C to 85°C
Storage Temperature Range ……………………………………..…………… -65°C to 150 °C
Lead Temperature (Soldering 10 Sec.) ………………………..…………………………260°C
n TEST CIRCUIT
SS6639
2.5V
VOUT
EXT
FOUT
GND
Oscillator Test Circuit
Rev.2.01 6/26/2003
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SS6639
n
ELECTRICAL CHARACTERISTICS
(TA=25°C, IO=10mA, unless otherwise specified)
PARAMETER
Output Voltage
TEST CONDITIONS
SS6639-27
SS6639-30
SS6639-33
SS6639-50
VIN=1.8V
VIN=1.8V
VIN=2.0V
VIN=3.0V
Input Voltage
SYMBOL
MIN.
TYP.
MAX.
UNIT
VOUT
2.633
2.925
3.218
4.875
2.700
3.000
3.300
5.000
2.767
3.075
3.382
5.125
V
8
V
0.9
V
VIN
Start-Up Voltage
IOUT=1mA, VIN:0→2V
VSTART
Hold-on Voltage
IOUT=1mA, VIN:2→0V
VHOLD
No-Load Input Current
IOUT=0mA
Supply Current 1
SS6639-27
SS6639-30
SS6639-33
SS6639-50
0.8
0.6
V
IIN
18
µA
IDD1
45
50
60
80
µA
IDD2
7
7
7
7
µA
EXT at no load, VIN=VOUT x 0.95
Supply Current 2
Measurement of the IC input
current (VOUT Pin)
SS6639-27
SS6639-30
SS6639-33
SS6639-50
EXT at no load, VIN=VOUT + 0.95
EXT “H” On-Resistance
EXT “L” On-Resistance
Rev.2.01 6/26/2003
Measurement of the IC input
current (VOUT Pin)
SS6639-27
SS6639-30
SS6639-33
SS6639-50
VEXT=VOUT – 0.4V
SS6639-27
SS6639-30
SS6639-33
SS6639-50
VEXT= 0.4V
REXTH
REXTL
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300
200
185
130
110
80
70
60
Ω
Ω
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SS6639
n ELECTRICAL CHARACTERISTICS
PARAMETER
(Continued)
TEST CONDITIONS
SYMBOL
MIN.
TYP.
MAX.
UNIT
DUTY
65
75
85
%
FOSC
80
105
130
KHz
VIN=VOUT x 0.95
Oscillator Duty Cycle
Measurement of the EXT Pin
Waveform
VIN=VOUT x 0.95
Max. Oscillator Freq.
Measurement of the EXT Pin
Waveform
η
Efficiency
80
%
n TYPICAL PERFORMANCE CHARACTERISTICS
Capacitor (C1): 47µF (Tantalum Type)
Diode
Transistor (Q1): 2SD1803
(D1): 1N5819 Schottky Type
2.80
90
2.75
85
2.70
V I N = 2.0
V
V I N = 1.8V
2.65
2.60
Efficiency (%)
Output Voltage (V)
Inductor (L1): 33µH (Pin Type)
V I N = 1.5
V
V IN = 1.2
V
2.55
2.50
V I N = 2.0V
80
75
V IN =1.8V
70
V I N = 1.5V
V I N = 1.2V
65
60
V IN = 0.9V
2.45
V I N =0.9V
2.40
0
50
100
55
150
200
250
300
350
400
450
50
500
0
50
100
150
Fig. 1 SS6639-27 Load Regulation (L=33µH)
250
300
350
400
450
500
Fig. 2 SS6639-27 Efficiency (L=33uH)
3.1
90
3.0
85
VIN=2.0V
VIN=2.0V
2.9
VIN=1.2V
2.8
VIN=1.5V
Efficiency (%)
Output Voltage (V)
200
Output Current (mA)
Output Current (mA)
VIN=1.8V
2.7
VIN=0.9V
80
VIN=1.8V
75
VIN=1.5V
70
2.6
VIN=1.2V
65
2.5
VIN=0.9V
2.4
60
0
50
100
150
200
250
300
350
400
Output Current (mA)
Fig. 3 SS6639-30 Load Regulation (L=33µH)
Rev.2.01 6/26/2003
450
0
50
100
150
200
250
300
350
400
450
Output Current (mA)
Fig. 4 SS6639-30 Efficiency (L=33µH)
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SS6639
n TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
90
3.4
85
VIN=2.0V
VIN=1.5V
Efficiency (%)
Output Voltage (V)
3.2
3.0
2.8
VIN=1.2V
2.6
2.4
80
VIN=2.0V
75
70
VIN=1.5V
65
60
0
50
100
150
200
250
300
350
400
VIN=0.9V
0
90
5.00
85
100
150
200
250
300
80
4.75
VIN=3.0V
VIN=2.0V
4.50
Efficiency (%)
Output Voltage (V)
5.25
V IN =1.5V
4.25
4.00
3.75
50
VIN=0.9V
400
VIN=3.0V
75
VIN=1.5V
70
VIN=2.0V
VIN=0.9V
65
VIN=1.2V
60
55
50
VIN=1.2V
3.50
350
Output Current (mA)
Fig. 6 SS6639-33 Efficiency (L=33µH)
Output Current (mA)
Fig. 5 SS6639-33 Loading Regulation (L=33µH)
45
3.25
0
100
200
300
400
500
600
40
700
0
Output Current (mA)
Fig. 7 SS6639-50 Load Regulation (L=33µH)
100
200
300
400
500
600
700
Output Current (mA)
Fig. 8 SS6639-50 Efficiency (L=33µH)
1.2
2.0
1.8
1.0
Input Voltage (V)
Output Voltage (V)
1.6
1.4
Start up
1.2
1.0
0.8
0.6
Hold on
0.4
Start up
0.8
0.6
Hold on
0.4
0.2
0.2
0.0
0
20
40
60
80
100
120
140
160
180
200
0.0
0
20
Output Current (mA)
Fig. 9 SS6639-27 Start-up & Hold-on Voltage (L=33µH)
Rev.2.01 6/26/2003
40
60
80
100
Output Current (mA)
120
140
160
Fig. 10 SS6639-30 Start-up & Hold-on Voltage (L=33µH)
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SS6639
n TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
1.2
1.6
Start up
1.4
Start up
1.2
Input Voltage (V)
Input Voltage (V)
1.0
0.8
0.6
Hold on
0.4
1.0
0.8
Hold on
0.6
0.4
0.2
0.2
0.0
0
20
40
60
80
100
120
140
0.0
160
0
20
40
60
80
100
120
140
160
Output Current (mA)
Output Current (mA)
Fig. 12 SS6639-50 Start-up & Hold-on Voltage (L=33uH)
Fig. 11 SS6639-33 Start-up & Hold-on Voltage (L=33µH)
1.2
1.6
Start up
1.4
1.0
Start up
Input Voltage (V)
Input Voltage (V)
1.2
0.8
0.6
Hold on
0.4
1.0
0.8
Hold on
0.6
0.4
0.2
0.2
0.0
0
20
40
60
80
100
120
140
0.0
160
0
20
40
60
Fig. 13 SS6639-33 Start-up & Hold-on Voltage (L=33µH)
140
160
130
Switching Frequency (kHz)
VOUT =5.0V
Output Voltage (V)
120
135
5.5
5.0
4.5
V OUT = 3.3V
V OUT = 3.0V
V OUT = 2.7V
4.0
3.5
3.0
2.5
V OUT = 5.0V
V OUT = 3.3V
V OUT = 3.0V
V OUT = 2.7V
125
120
115
110
105
100
95
90
-20
0
20
40
60
80
Output Current (mA)
Fig. 15 SS6639 Output Voltage vs. Temperature
Rev.2.01 6/26/2003
100
Fig. 14 SS6639-50 Start-up & Hold-on Voltage (L=33uH)
6.0
2.0
-40
80
Output Current (mA)
Output Current (mA)
100
85
-40
-20
0
20
40
60
80
100
Output Current (mA)
Fig. 16 SS6639 Switching Frequency vs.Temperature
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SS6639
n TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
80
75
79
V OUT
2.7V
V OUT
3.0V
V OUT
78
77
76
Supply Current IDD1 (µA)
Maximum Duty Cycle (%)
80
=
=
=
75
74
73
72
65
60
55
50
45
40
35
71
70
-40
-20
0
20
40
60
80
30
-40
100
Fig. 17 SS6639 Maximum Duty Cycle vs. Temperature
120
2.7V
3.0V
3.3V
5.0V
320
90
80
70
280
40
60
80
100
200
160
120
50
80
-20
0
20
40
60
80
100
Temperature (°C)
Fig. 19 SS6639 EXT "L" On-Resistance
VOUT = 2.7V
VOUT = 3.0V
VOUT = 3.3V
VOUT = 5.0V
240
60
40
-40
20
360
VOUT =
VOUT =
VOUT =
VOUT =
Resistance (O)
100
0
400
130
110
-20
Temperature (°C)
Fig. 18 SS6639 Supply Current vs. Temperature
Output Current (mA)
Resistance (O)
V OUT = 5.0V
V OUT = 3.3V
V OUT = 3.0V
V OUT = 2.7V
70
40
-40
-20
0
20
40
60
80
100
Temperature (°C)
Fig. 20 SS6639 EXT "H" On-Resistance
n BLOCK DIAGRAM
1.25V REF.
VOUT
1M
-
EXT
+
Enable
GND
Rev.2.01 6/26/2003
OSC, 100KHz
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SS6639
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PIN DESCRIPTIONS
Pin 1:
GND:
Ground. Must be low impedance;
Pin 3:
EXT:
power. Switch.
solder directly to ground plane.
Pin 2:
VOUT:
Push-pull driver output for external
IC supply pin. Connect Vout to the
regular output.
n
APPLICATION INFORMATION
General Description
The SS6639 PFM (pulse frequency modulation)
controller IC combines a switch mode regulator, a
push-pull driver, a precision voltage reference, and a
voltage detector in a single monolithic device. It
offers extremely low quiescent current, high
efficiency, and very low gate-threshold voltage to
ensure start-up with low battery voltage (0.8V typ.).
Designed to maximize battery life in portable
products, it minimizes switching losses by only
switching as needed to service the load.
PFM controllers transfer a discrete amount of energy
per cycle and regulate the output voltage by
modulating the switching frequency with a constant
turn-on time. Switching frequency depends on load,
input voltage, and inductor value and can range up
to 100 KHz.
When the output voltage drops, the error comparator
enables the 100 kHz oscillator which turns the
MOSFET on for around 7.5us and off for 2.5µs.
Turning on the MOSFET allows inductor current to
ramp up, storing energy in the magnetic field.
When the MOSFET turns off, the inductor forces
current through the diode to the output capacitor and
the load. As the stored energy is depleted, the
current ramps down until the diode turns off. At this
point, the inductor may ring due to residual energy
and stray capacitance. The output capacitor stores
charge when current flowing through the diode is
high, and releases it when current is low, thereby
maintaining a steady voltage across the load.
Rev.2.01 6/26/2003
As the load increases, the output capacitor
discharges faster and the error comparator initiates
cycles sooner, increasing the switching frequency.
The maximum duty cycle ensures adequate time for
energy transfer to the output during the second half
of each cycle. Depending on the circuit, PFM
controllers can operate in either discontinuous mode
or continuous conduction mode. The continuous
conduction mode means that the inductor current
does not ramp to zero during each cycle.
VIN
IIN
ID
IOUT
SW
+
EXT
Isw
VOUT
Ico
Discontinuous Conduction Mode
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SS6639
At
VEXT
the
boundary
between
continuous
and
discontinuous modes, the output current (IOB) is
determined by
IIN
VIN

 1 VIN
IOB = 
* TON * (1 − x )
* *
 VOUT + VD  2 L
IPK
where VD is the diode drop,
X = (RON + RS) ∗
ISW
TON
L
RON= Switch turn on resistance, RS= Inductor DC
resistance
Charge Co.
ID
TON = Switch ON time
IOUT
In the discontinuous mode, the switching frequency
TDIS
VSW
Discharge Co.
(Fsw) is
FSW =
t
VEXT
VIN 2 * TON 2
* (1 + x )
In the continuous mode, the switching frequency is
fsw =
Discontinuous Conduction Mode
2(L) * (VOUT + VD − VIN) * (IOUT)
(VOUT + VD − VIN )
1
*
TON (VOUT + VD − VSW )
x
VIN − VSW
* [1 + (
)]
2 VOUT + VD − VSW
1  VOUT + VD − VIN 
≅
*

TON  VOUT + VD − VSW 
where Vsw = switch drop and is proportional to
IIN
output current.
IPK
ISW
ID
IOUT
VSW
t
Continuous Conduction Mode
Rev.2.01 6/26/2003
INDUCTOR SELECTION
To operate as an efficient energy transfer element,
the inductor must fulfill three requirements. First, the
inductance must be low enough for the inductor to
store adequate energy under the worst case
condition of minimum input voltage and switch ON
time. Second, the inductance must also be high
enough so the maximum current rating of the
SS6639 and the inductor are not exceeded at the
other worst case condition of maximum input voltage
and ON time. Lastly, the inductor must have
sufficiently low DC resistance so excessive power is
not lost as heat in the windings. Unfortunately this is
inversely related to physical size.
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SS6639
Minimum and maximum input voltage, output voltage
Power required from the inductor per cycle must be
and output current must be established before an
equal to, or greater than
inductor can be selected.
In discontinuous mode operation, at the end of the
PL
1
= (VOUT + VD − VIN) * (IOUT) * (
)
fSW
fsw
switch ON time, peak current and energy in the
in order for the converter to regulate the output.
inductor build according to
When the loading exceeds IOB, the PFM controller
RON + RS

 VIN  
IPK = 
* TON) 
 * 1 − exp(−
L

 RON + RS  
x
 VIN 

≅
 * ( TON) * 1 − 
L
2




operates in continuous mode. Inductor peak current
≅
VIN
* TON
L
can be derived from
 VOUT + VD − VSW x 
IPK = 
− 
VIN − VSW
2

x
 VIN − VSW 

* IOUT + 
 * TON * 1 − 
2L
2



(simple lossless equation), where
X = (RON + RS) ∗
EL =
TON
L
Valley current (Iv) is
 VOUT + VD − VSW x 
IV = 
−  * IOUT
VIN − VSW
2

x
 VIN − VDE 

*
 * T ON * 1 − 
2L
2



1
L * IPK 2
2
Table 1 Indicates resistance and height for each coil.
Power Inductor Type
Inductance ( µH ) Resistance ( Ω ) Rated Current (A) height (mm)
47
0.25
0.7
100
0.50
0.5
47
0.25
0.7
100
0.50
0.5
Hold SMT Type PM75
33
0.11
1.2
5.0
Huan Feng PIN Type V0810
33
40m
2
10.0
Sumida SMT Type CD54
Hold SMT Type PM54
4.5
4.5
CAPACITOR SELECTION
A poor choice for an output capacitor can result in poor
efficiency and high output ripple. Ordinary aluminum
electrolytic capacitors, while inexpensive, may have
unacceptably poor ESR and ESL. There are low ESR
aluminum capacitors for switch mode DC-DC
converters which work much better than
general-purpose components. Tantalum capacitors
provide still better performance but are more
expensive. OS-CON capacitors have extremely low
ESR in a small size. If the capacitance is reduced, the
Rev.2.01 6/26/2003
output ripple will increase.
As most of the input supply is applied across the input
bypass capacitor, the capacitor voltage rating should
be at least 1.25 times greater than the maximum input
voltage.
DIODE SELECTION
Speed, forward drop, and leakage current are three
main considerations in selecting a rectifier diode. The
best performance is obtained with a Schottky rectifier
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SS6639
diode such as the 1N5819. Motorola makes the
MBR0530 for surface mount. For lower output power a
1N4148 can be used although efficiency and start-up
voltage will suffer substantially.
where POUT=VOUT * IOUT ; RS=Inductor DC R;
VD = Diode drop.
The power dissipated in switching losses is
PDsw =
COMPONENT POWER DISSIPATION
2
3
 TON 
*
 * (RON ) * (IOUT ) * (POUT )
 L 
Operating in discontinuous mode, the power loss in
The power dissipated in the rectifier diode is
the winding resistance of the inductor is approximately
 VD 
PDD = 
 * (POUT )
 VOUT 
equal to
PDL =
2  TON 
 VOUT + VD 
*
 * (RS ) * 
 * (POUT )
3  L 
 VOUT 
Rev.2.01 6/26/2003
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SS6639
n
PHYSICAL DIMENSIONS
• SOT-89 (unit: mm)
A
D
D1
C
H
E
L
B
e
e1
l
SYMBOL
MIN
MAX
A
1.40
1.60
B
0.36
0.48
C
0.35
0.44
D
4.40
4.60
D1
1.62
1.83
E
2.29
2.60
e
1.50 (TYP.)
e1
3.00 (TYP.)
H
3.94
4.25
L
0.89
1.20
SYMBOL
MIN
MAX
A
4.32
5.33
SOT-89 MARKING
Part No.
Marking
SS6639-27
AU27
SS6639-30
AU30
SS6639-33
AU33
SS6639-50
AU50
• TO-92 (unit: mm)
A
E
L
C
C
e1
D
0.38 (TYP.)
D
4.40
5.20
E
3.17
4.20
e1
L
1.27 (TYP.)
12.7
-
Information furnished by Silicon Standard Corporation is believed to be accurate and reliable. However, Silicon Standard Corporation makes no
guarantee or warranty, express or implied, as to the reliability, accuracy, timeliness or completeness of such information and assumes no
responsibility for its use, or for infringement of any patent or other intellectual property rights of third parties that may result from its
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without limitation enhancement in reliability, functionality or design. No license is granted, whether expressly or by implication, in relation to
the use of any products described herein or to the use of any information provided herein, under any patent or other intellectual property rights of
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Rev.2.01 6/26/2003
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