SSC SS6642

SS6642G
3-Pin Simple Step-Up DC/DC Converter
FEATURES
DESCRIPTION
The SS6642G is a high efficiency step-up DC/DC
converter for applications using 1 to 4 NiMH battery cells. Only three external components are required to deliver a fixed output voltage of 2.7V,
3.0V, 3.3V, 3.7V, 4.5V or 5V. The SS6642G starts
up from less than 0.9V input with 1mA load. A
Pulse Frequency Modulation scheme optimizes
performance for applications with light output
loading and low input voltages. The output ripple
and noise are lower when compared with circuits
operating in PSM mode.
A guaranteed start-up from less than 0.9 V.
High efficiency.
Low quiescent current.
Fewer external components needed.
Low ripple and low noise.
Fixed output voltage: 2.7V, 3.0V, 3.3V, 3.7V,
4.5V and 5V.
Space-saving packages: SOT-23, SOT-89 and
TO-92.
Pb-free, RoHS compliant.
APPLICATIONS
The PFM control circuit operating at a 100KHz
Pagers.
Cameras.
Wireless Microphones.
Pocket Organizers.
Battery Backup Suppliers.
Portable Instruments.
(max.) switching rate results in smaller passive
components. The space saving SOT-23, SOT89 and TO-92 packages make the SS6642G an
ideal choice for DC/DC converter for space conscious applications, such as pagers, electronic
cameras, and wireless microphones.
TYPICAL APPLICATION CIRCUIT
VIN
VOUT
L1
100µH
D1
SS12
SS6642-xxG
+
+
C1
SW
22µF
VOUT
C2
47µF
GND
One Cell Step-Up DC/DC Converter
1/15/2005 Rev.2.10
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SS6642G
ORDERING INFORMATION
PIN CONFIGURATION
SS6642-XXXXXX
Packing type
TR: Tape and reel
TB: Tube
Package type
GU: RoHS-compliant SOT-23
GX: RoHS-compliant SOT-89
GZ: RoHS-compliant TO-92
Output voltage
27: 2.7V
30: 3.0V
33: 3.3V
37: 3.7V
45: 4.5V
50: 5.0V
SOT-89
TOP VIEW
1: GND
2: VOUT
3: SW
1
TO-92
TOP VIEW
1: GND
2: VOUT
3: SW
2
3
1
2
3
SOT-23
TOP VIEW
1: GND
2: SW
3: VOUT
3
1
2
Example: SS6642-27GXTR
2.7V output version, in RoHS-compliant SOT-89
shipped on tape and reel.
SOT-23 MARKING
Part No.
GU
SS6642-27G
GM27P
SS6642-30G
GM30P
SS6642-33G
GM33P
SS6642-37G
GM37P
SS6642-45G
GM45P
SS6642-50G
GM50P
SOT-89 MARKING
1/15/2005 Rev.2.10
Part No.
GX
SS6642-27G
AM27P
SS6642-30G
AM30P
SS6642-33G
AM33P
SS6642-37G
AM37P
SS6642-45G
AM45P
SS6642-50G
AM50P
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SS6642G
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (VOUT pin)
.6V
SW pin Voltage
6V
SW pin Switch Current
0.6A
Operating Temperature Range
-40°C to 85°C
Maximum Junction Temperature
125°C
-65°C to 150°C
Storage Temperature Range
Lead Temperature (Soldering 10 Sec.)
260°C
Absolute Maximum Ratings are those values beyond which the life of a device may be impaired.
TEST CIRCUIT
VIN
VOUT
IIN
D1
SS12
L1
100µH
IS
SS6642-xxG
+ C2
22µF SW
VOUT
SS6642
VOUT
VS
+ C1
47µF
SW
VSW
GND
GND
Fig. 1 Test Circuit 1
Fig. 2 Test Circuit 2
SS6642
100W
VS
VOUT
SW
FOSC
GND
Fig. 3 Test Circuit 3
1/15/2005 Rev.2.10
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SS6642G
ELECTRICAL CHARACTERISTICS
(TA=25°C, IOUT=10mA, unless otherwise specified)
(Note1)
PARAMETER
Output Voltage
TEST CONDITIONS
TEST
CKT
SYMBOL
TYP.
MAX.
SS6642-27G
VIN=1.8V
2.633
2.700
2.767
SS6642-30G
VIN=1.8V
2.925
3.000
3.075
SS6642-33G
VIN=2.0V
3.218
3.300
3.382
3.607
3.700
3.792
1
VOUT
UNIT
V
SS6642-37G
V IN=2.0V
SS6642-45G
VIN=3.0V
4.387
4.500
4.613
SS6642-50G
VIN=3.0V
4.875
5.000
5.125
0.8
0.9
V
0.7
V
Start-Up Voltage
IOUT=1mA, VIN:0→2V
1
VSTART
Min. Hold-on Voltage
IOUT=1mA, VIN:2→0V
1
VHOLD
No-Load Input Current
IOUT=0mA
1
IIN
Supply Current
MIN.
SS6642-27G
42
SS6642-30G
50
SS6642-33G
60
SS6642-37G
65
SS6642-45G
2
IS1
µA
15
µA
70
90
SS6642-50G
VS=VOUT x 0.95
Measurement of the IC
input current (VOUT pin)
Supply Current
SS6642-27G
7
SS6642-30G
7
SS6642-33G
7
SS6642-37G
7
SS6642-45G
2
IS2
µA
7
7
SS6642-50G
VS=VOUT + 0.5V
Measurement of the IC input current (VOUT pin)
SW Leakage Current
1/15/2005 Rev.2.10
VSW=6V, VS=VOUT + 0.5V
2
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0.5
µA
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SS6642G
ELECTRICAL CHARACTERISTICS
PARAMETER
(Continued)
TEST CONDITIONS
SYMBOL
MIN.
TYP.
SS6642-27G
2.2
SS6642-30G
2.1
SS6642-33G
2.0
SS6642-37G
SW Switch-On Resistance
TEST
CKT
2
SS6642-45G
MAX.
UNIT
2.0
RON
Ω
1.9
1.9
SS6642-50G
VS=VOUT x 0.95,
VSW=0.4V
VS=VOUT x 0.95
Oscillator Duty Cycle
Measurement of the SW
pin waveform
3
DUTY
65
75
85
%
3
FOSC
80
105
130
KHz
1
η
VS=VOUT x 0.95
Max. Oscillator Freq.
Measurement of the SW
pin waveform
Efficiency
85
%
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).
TYPICAL PERFORMANCE CHARACTERISTICS
2.8
85
2.7
80
2.6
VIN =1.5V
VIN =1.8V
VIN =2.0V
V IN =1.2V
2.5
2.4
Efficiency (%)
Output Voltage (V)
Test circuit refer to typical application circuit
Capacitor (C2) : 47 µ F (Tantalum Type)
Diode (D1) : 1N5819 Schottky Type
75
VIN =1.8V
70
65
VIN =1.5V
V IN =0.9V
60
2.3
VIN =1.2V
VIN =0.9V
2.2 0
55
20
40
60
80
100
120
140
160
180
0
20
40
Fig. 4 SS6642-27 Load Regulation (L=100µH CD54)
60
80
100
120
140
160
180
Output current (mA)
Output Current (mA)
1/15/2005 Rev.2.10
VIN =2.0V
Fig. 5 SS6642-27 Efficiency (L=100µH CD54)
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SS6642G
TYPICAL PERFORMANCE CHARACTERISTICS
2.8
(Continued)
85
80
2.7
Efficiency (%)
Output Voltage (V)
75
2.6
VIN=1.5V
VIN=1.2V
VIN=2.0V
VIN=1.8V
2.5
70
VIN=2.0V
VIN=1.8V
65
60
VIN=1.2V
2.4
VIN=1.5V
VIN=0.9V
55
VIN=0.9V
2.3
0
20
40
60
80
100
120
140
160
180
200
220
50
240
0
20
40
60
Output Current (mA)
Fig. 6
SS6642-27 Load Regulation (L=47µH CD54)
120
140
160
180
220 240
200
1.0
0.9
0.9
0.8
Start up
Input Voltage (V)
0.6
0.5
Hold on
0.4
Start up
0.8
0.7
Input Voltage (V)
100
Output current (mA)
SS6642-27 Efficiency (L=47µH CD54)
Fig. 7
1.0
80
0.3
0.2
0.7
0.6
0.5
Hold on
0.4
0.3
0.2
0.1
0.1
0.0
0
Fig. 8
2
4
6
8
10
12
14
16
0.0
18
0
2
4
6
8
10
12
14
16
18
Output Current (mA)
Output Current (mA)
SS6642-27 Start-Up & Hold-ON Voltage (L=47µH CD54)
Fig. 9 SS6642-27 Start-Up & Hold-ON Voltage (L=100µH CD54)
2.80
160
2.78
Switching Frequency (kHz)
2.76
Output Voltage (V)
2.74
2.72
2.70
2.68
2.66
2.64
140
120
100
80
60
2.62
2.60
-40
-20
0
20
40
60
80
Temperature (°C)
Fig. 10 SS6642-27 Output Voltage vs. Temperature
1/15/2005 Rev.2.10
100
40
-40
-20
0
20
40
60
80
100
Temperature (°C)
Fig. 11 SS6642-27 Switching Frequency vs. Temperature
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SS6642G
TYPICAL PERFORMANCE CHARACTERISTICS
1.8
SW Turn ON Resistance (Ω)
Maximum Duty Cycle (%)
80
(Continued)
78
76
74
72
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
70
-40
0.0
-20
0
20
40
60
80
100
Temperature (°C)
Fig. 12 SS6642-27 Maximum Duty Cycle vs. Temperature
-40
-20
0
20
40
60
80
100
Temperature (°C)
Fig. 13 SS6642-27 SW Turn ON Resistance vs. Temperature
45
3.1
VIN=2.0V
3.0
40
Output voltage VOUT(V)
Supply Current (µA)
2.9
35
30
25
20
15
VIN=1.5V
2.8
VIN=1.8V
2.7
2.6
2.5
2.4
2.3
VIN=1.2V
2.2
10
VIN=0.9V
2.1
5
-40
-20
0
20
40
60
80
2.0
100
0
Temperature (°C)
Fig. 14 SS6642-27 Supply Current vs. Temperature
10
20
30
40
50
60
70
80
90
100 110 120 130 140
Output Current (mA)
Fig. 15 SS6642-30 Load Regulation (L=100µH, CD54)
85
3.1
3.0
80
2.9
Output Voltage (V)
Efficiency (%)
75
70
VIN=1.8V
65
60
VIN=2.0
VIN=1.2V
2.8
VIN=1.5V
VIN=1.8V
VIN=2.0V
2.7
2.6
2.5
VIN=1.5V
2.4
55
2.3
VIN=1.2V
VIN=0.9V
2.2
50
0
20
40
60
80
100
120
140
160
180
VIN=0.9V
0
20
40
1/15/2005 Rev.2.10
80
100
120
140
160
180
200
220
Output Current (mA)
Output Current (mA)
Fig. 16 SS6642-30 Efficiency (L=100µH, CD54)
60
Fig. 17 SS6642-30 Load Regulation (L=47µH CD54)
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SS6642G
TYPICAL PERFORMANCE CHARACTERISTICS
85
(Continued)
1.0
Start up
0.9
80
0.8
Input Voltage (V)
Efficiency (%)
75
70
65
VIN=2.0V
VIN=1.8V
60
0.7
0.6
Hold on
0.5
0.4
0.3
0.2
55
VIN=1.5V
VIN=0.9V
50
0
0.1
VIN=1.2V
25
50
75
100
125
150
175
200
0.0
225
0
Output Current (mA)
Fig. 18
Fig. 19
SS6642-30 Efficiency (L=47µH CD54)
4
6
8
10
12
14
16
18
20
Output Current (mA)
SS6642-30 Start-up & Hold-on Voltage (L=100µH CD54)
3.10
1.0
3.08
Start up
0.9
3.06
Output Voltage (V)
0.8
Input Voltage (V)
2
0.7
0.6
0.5
Hold on
0.4
0.3
3.02
3.00
2.98
2.96
0.2
2.94
0.1
2.92
2.90
-40
0.0
0
2
4
6
8
10
12
14
16
18
No Load
3.04
20
-20
0
20
40
60
80
100
Temperature (°C)
Fig. 21 SS6642-30 Output Voltage vs. Temperature
Output Current (mA)
Fig. 20 SS6642-30 Start-up & Hold-on Voltage (L=47µH CD54)
80
Maximum Duty Cycle (%)
Switching Frequency (kHz)
160
140
120
100
80
60
40
-40
-20
0
20
40
60
80
Temperature (°C)
Fig. 22 SS6642-30 Switching Frequency vs. Temperature
1/15/2005 Rev.2.10
100
78
76
74
72
70
-40
-20
0
20
40
60
80
100
Temperature (°C)
Fig. 23 SS6642-30 Maximum Duty Cycle vs. Temperature
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SS6642G
TYPICAL PERFORMANCE CHARACTERISTICS
45
1.8
1.6
40
1.4
35
Supply Current (µA)
SW Turn ON Resistance (Ω)
(Continued)
1.2
1.0
0.8
0.6
30
25
20
15
0.4
10
0.2
0.0
-40
Fig. 24
-20
0
20
40
60
80
5
-40
100
Temperature (°C)
SS6642-30 SW Turn ON Resistance vs. Temperature
-20
0
20
40
60
80
100
Temperature (°C)
Fig. 25 SS6642-30 Supply Current vs. Temperature
90
3.4
VIN=2.0V
3.3
85
3.1
80
VIN=1.8V
VIN=1.5V
Efficiency (%)
Output Voltage (V)
3.2
3.0
2.9
VIN=1.2V
2.8
2.7
2.6
VIN=2.0V
75
70
VIN=1.8V
65
60
VIN=1.2V
2.5
2.3
55
VIN=0.9V
2.4
0
25
50
75
100
125
150
175
50
200
VIN=0.9V
0
25
50
Output Current (mA)
SS6642-33 Load Regulation (L=100µH, CD54)
90
3.3
85
3.2
80
VIN=1.5V
VIN=2.0V
VIN=1.8V
3.0
2.9
2.8
VIN=1.2V
2.4
0
25
50
75
175
200
VIN=2.0V
65
60
VIN=1.8V
VIN=1.5V
VIN=0.9V
VIN=1.2V
45
100
125
150
175
200
Output Current (mA)
Fig. 28 SS6642-33 Load Regulation (L=47µH, CD54)
1/15/2005 Rev.2.10
150
70
50
VIN=0.9V
2.5
125
75
55
2.7
2.6
100
SS6642-33 Efficiency (L=100µH, CD54)
Fig. 27
3.4
3.1
75
Output Current (mA)
Efficiency (%)
Output Voltage (V)
Fig. 26
VIN=1.5V
225
40
0
25
50
75
100
125
150
175
200
225
250
Output Current (mA)
Fig. 29
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SS6642-33 Efficiency (L=47µH,CD54)
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SS6642G
TYPICAL PERFORMANCE CHARACTERISTICS
3.50
1.1
1.0
3.45
Output Voltage Vout (V)
Start up
0.9
Input Voltage (V)
0.8
0.7
0.6
0.5
Hold on
0.4
0.3
0.2
3.40
3.35
No Load
3.30
3.25
3.20
3.15
3.10
3.05
0.1
0.0
(Continued)
0
2
4
6
8
10
12
14
16
18
3.00
-40
20
-20
0
20
40
60
80
100
Temperature (°C)
Output Current (mA)
Fig. 30 SS6642-33 Start-up & Hold-on Voltage (L=100µH CD54)
Fig. 31
SS6642-33 Output Voltage vs. Temperature
80
Maximum Duty Cycle (%)
Switching Frequency (kHz)
160
140
120
100
80
60
40
-40
-20
0
20
40
60
80
100
76
74
72
70
-40
1.8
45
1.6
40
1.4
1.2
1.0
0.8
0.6
0.4
-20
Fig. 33
Supply Current IDD1 (µA)
SW Turn ON Resistance (Ω)
Temperature (°C)
Fig. 32 SS6642-33 Switching Frequency vs. Temperature
78
0
20
40
60
80
100
Temperature (°C)
SS6642-33 Maximum Duty Cycle vs. Temperature
35
30
25
20
15
0.2
0.0
-40
Fig. 34
-20
0
20
40
60
80
100
Temperature (°C)
SS6642-33 SW Turn ON Resistance vs. Temperature
1/15/2005 Rev.2.10
10
-40
-20
0
20
40
60
80
100
Temperature (°C)
Fig. 35 SS6642-33 Supply Current vs. Temperature
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SS6642G
TYPICAL PERFORMANCE CHARACTERISTICS
90
3.8
3.7
85
3.6
80
VIN=1.2V
3.4
VIN=2.5V
3.3
VIN=1.8V
3.2
75
Efficiency (%)
Output Voltage (V)
3.5
VIN =2.0V
3.1
3.0
2.9
2.8
2.7
VIN =2.5V
70
65
VIN=1.2V
60
VIN =0.9V
2.5
2.4
25
0
50
VIN=1.8V
VIN=0.9V
45
75
100
125
150
175
200
225
250
40
275
0
Output Current (mA)
Fig. 36 SS6642-37 Load Regulation (L=100µH)
75
100
125
150
175
200
225
250
85
3.6
3.5
80
3.4
VIN=2.5V
3.3
75
VIN=2.0V
VIN=1.8V
3.2
Efficiency (%)
Output Voltage (V)
50
90
3.7
3.1
3.0
2.9
VIN=1.2V
2.8
2.7
VIN=2.5V
70
65
VIN=1.8V
60
55
2.5
45
VIN=0.9V
2.4
0
25
50
75
VIN=2.0V
VIN=0.9V VIN=1.2V
50
2.6
100
125
150
175
200
225
250
40
275
0
Output Current (mA)
Fig. 38 SS6642-37 Load Regulation (L=47µH)
25
50
75
100
125
150
175
200
225
250
275
Output Current (mA)
Fig. 39 SS6642-37 Efficiency (47µH)
4.00
1.6
3.95
1.4
3.90
3.85
Output Voltage (V)
1.2
Input Voltage (V)
25
Output Current (mA)
Fig. 37 SS6642-37 Efficiency (100µH)
3.8
Start up
3.80
1.0
No Load
3.75
0.8
3.70
3.65
Hold on
0.6
3.60
0.4
3.55
3.50
0.2
0.0
VIN=2.0V
55
50
2.6
2.3
(Continued)
3.45
0
5
10
15
20
Output Current (mA)
Fig. 40 SS6642-37 Start-up & Hold-on Voltage (L=100µH)
1/15/2005 Rev.2.10
3.40
-40
-20
0
20
40
60
80
100
Temperature (°C)
Fig. 41 SS6642-37 Output Voltage vs. Temperature
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SS6642G
TYPICAL PERFORMANCE CHARACTERISTICS
(Continued)
80
Maximum Duty Cycle (%)
Switching Frequency (KHz)
160
140
120
100
80
60
40
-40
-20
0
20
40
60
80
76
74
72
70
-40
100
Temperature (°C)
Fig. 42 SS6642-37 Switching Frequency vs. Temperature
78
-20
0
20
40
60
80
100
Temperature (°C)
Fig. 43 SS6642-37 Maximum Duty Cycle vs Temperature
90
4.6
4.4
85
80
4.0
VIN=3.0V
3.8
Efficiency (%)
Output Voltage (V)
4.2
VIN=1.5V
3.6
VIN=2.0V
3.4
3.2
VIN=0.9V
3.0
VIN=1.2V
75
70
VIN=3.0V
65
VIN=2.0V
60
VIN=1.5V
2.8
VIN=0.9V
55
2.6
2.4
VIN=1.2V
50
2.2
0
50
100
150
200
250
300
350
0
400
Output Current (mA)
Fig. 44 SS6642-45 Load Regulation (L=100µH)
50
100
150
200
250
300
350
400
Output Current (mA)
Fig. 45 SS6642-45 Efficiency (L=100µH)
1.6
4.6
4.4
1.4
1.2
4.0
VIN=3.0V
3.8
Input Voltage (V)
Output Voltage (V)
4.2
VIN=1.5V
3.6
VIN=2.0V
3.4
3.2
VIN=0.9V
3.0
VIN=1.2V
Start up
1.0
Hold on
0.8
0.6
0.4
2.8
2.6
0.2
2.4
0.0
2.2
0
50
100
150
200
250
300
350
Output Current (mA)
Fig. 46 SS6642-45 Load Regulation (L=100µH)
1/15/2005 Rev.2.10
400
0
5
10
15
20
Output Current (mA)
Fig. 47 SS6642-45 Start-up & Hold-On Voltage (L=100µH)
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SS6642G
TYPICAL PERFORMANCE CHARACTERISTICS
5.0
90
4.9
80
4.7
4.6
70
Supply Current (µA)
Output Voltage (V)
4.8
No Load
4.5
4.4
4.3
60
50
40
30
4.2
20
4.1
4.0
(Continued)
-40
-20
0
20
40
60
80
10
100
-40
Temperature (°C)
Fig. 48 SS6642-45 Output Voltage vs. Temperature
-20
0
20
40
60
80
100
Temperature (°C)
Fig. 49 SS6642-45 Supply Current vs. Temperature
80
Maximum Duty Cycle (%)
Switching Frequency (kHz)
160
140
120
100
80
60
40
-40
-20
0
20
40
60
80
100
Temperature (°C)
Fig. 50 SS6642-45 Switching Frequency vs. Temperature
78
76
74
72
70
-40
0
20
40
60
80
100
Temperature (°C)
Fig. 51 SS6642-45 Maximum Duty Cycle vs. Temperature
5.5
1.8
1.6
5.0
1.4
4.5
Output Voltage (V)
SW Turn ON Resistance (Ω)
-20
1.2
1.0
0.8
0.6
0.4
VIN=3.0V
VIN=2.0V
4.0
3.5
VIN=1.5V
3.0
VIN=1.2V
2.5
VIN=0.9V
2.0
0.2
0.0
1.5
-40
-20
0
20
40
60
80
100
Temperature (°C)
Fig. 52 SS6642-45 SW Turn ON Resistance vs. Temperature
1/15/2005 Rev.2.10
0
50
100
150
200
250
300
350
400
Output Current (mA)
Fig. 53 SS6642-50 Load Regulation ( L=100µH CD54)
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SS6642G
TYPICAL PERFORMANCE CHARACTERISTICS
90
5.0
80
4.5
70
Output Voltage (V)
5.5
Efficiency (%)
100
VIN=3.0V
VIN=2.0V
60
VIN=0.9V
50
VIN=1.5V
VIN=1.2V
40
20
0
50
Fig. 54
100
150
200
250
300
350
3.5
VIN=1.5V
3.0
VIN=1.2V
2.5
VIN=0.9V
1.5
0
400
VIN=3.0V
VIN=2.0V
4.0
2.0
30
(Continued)
50
100
150
200
250
300
350
400
Output Current (mA)
Output Current (mA)
SS6642-50 Efficiency (L=100µH CD54)
Fig. 55 SS6642-50 Load Regulation (L=47µH CD54)
90
1.8
85
1.6
80
1.4
Input Voltage (V)
Efficiency (%)
75
70
VIN=3.0V
65
60
VIN=2.0V
55
50
VIN=0.9V
45
0
50
VIN=1.5V
1.0
Start up
0.8
Hold on
0.6
0.4
VIN=1.2V
100
1.2
0.2
150
200
250
300
350
0.0
400
0
2
4
6
Output Current (mA)
8
10
12
14
16
18
20
Output Current (mA)
Fig. 56 SS6642-50 Efficiency (L=47µH CD54)
Fig. 57 SS6642-50 Start-up & Hold-on Voltage (L=100µH CD50)
5.3
160
Switching Frequency (kHz)
Output Voltage VOUT (V)
5.2
5.1
No Load
5.0
4.9
4.8
4.7
4.6
4.5
4.4
-40
-20
0
20
40
60
80
Temperature (°C)
Fig. 58 SS6642-50 Output Voltage vs. Temperature
1/15/2005 Rev.2.10
100
140
120
100
80
60
40
-40
-20
0
20
40
60
80
100
Temperature (°C)
Fig. 59 SS6642-50 Switching Frequency vs. Temperature
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14 of 22
SS6642G
TYPICAL PERFORMANCE CHARACTERISTICS
1.8
SW Turn ON Resistance (Ω)
Maximum Duty Cycle (%)
80
(Continued)
78
76
74
72
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
70
-40
-20
0
20
40
60
80
100
Temperature (°C)
Fig. 60 SS6642-50 Maximum Duty Cycle vs. Temperature
0.0
-40
-20
0
20
40
60
80
100
Temperature (°C)
Fig. 61 SS6642-50 SW Turn ON Resistance vs. Temperature
100
90
VOUT
Supply Current IDD1 (µA)
80
50mV/div
70
60
10mA
50
40
Load Step
30
50mA/div
20
10
-40
-20
0
20
40
60
80
100
Temperature (°C)
Fig. 62 SS6642-50 Supply Current vs. Temperature
Fig. 63 Load Transient Response
(L1=100µH, C2=47µF, VIN=2V)
VOUT
20mv/div
VIN
0.5V/div
Fig. 64 Line Transient Response
(L1=100µH, C2=47µF)
1/15/2005 Rev.2.10
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15 of 22
SS6642G
BLOCK DIAGRAM
SW
1.25V REF.
VOUT
1M
+
Enable
GND
OSC, 100KHz
PIN DESCRIPTIONS
PIN 1 : GND - Ground. Must be low impedance;
solder directly to ground plane.
PIN 3 : SW –Drain of the internal N-channel
MOSFET switch.
PIN 2 : VOUT - IC supply pin. Connect VOUT
to the regulator output.
1/15/2005 Rev.2.10
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16 of 22
SS6642G
APPLICATION INFORMATION
GENERAL DESCRIPTION
The SS6642G PFM (pulse frequency modulation)
controller IC combines a switch-mode regulator, Nchannel power MOSFET, precision voltage reference, and voltage detector in a single monolithic
device. It offers extremely low quiescient 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 it can range
up to 100KHz. The SW on-resistance is typically
1.9 to 2.2Ω to minimize switch losses.
When the output voltage drops, the error comparator
enables the 100kHz oscillator that turns on the
MOSFET for around 7.5us and off for 2.5us. Turning
on the MOSFET allows inductor current to ramp up,
storing energy in a magnetic field. When the MOSFET
turns off, inductor current is forced through the diode to
the output capacitor and 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 the current flowing
through the diode is high, and releases it when the
current is low, thereby maintaining a steady voltage
across the load.
or continuous conduction mode. Continuous conduction
mode means that the inductor current does not
ramp down to zero during each cycle.
VIN
IIN
ID
IOUT
SW
VOUT
+
EXT
Isw
Ico
VEXT
IIN
IPK
ISW
Charge Co.
ID
IOUT
TDIS
VSW
Discharge Co.
t
Discontinuous Conduction Mode
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, a PFM
controller can operate in either discontinuous mode
1/15/2005 Rev.2.10
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17 of 22
SS6642G
In the continuous mode, the switching frequency is
VEXT
1 (VOUT + VD − VIN)
TON (VOUT + VD − VSW )
x
VIN − VSW
* [1 + (
)]
2 VOUT + VD − VSW
1  VOUT + VD − VIN 
≅


TON  VOUT + VD − VSW 
fSW =
IIN
IPK
ISW
where Vsw = switch drop and is proportional to
output current.
ID
IOUT
VSW
t
Continuous Conduction Mode
Continuous Conduction Mode
At the boundary between continuous and discontinuous modes, output current (IOB) is determined by
In discontinuous mode operation, at the end of
the switch ON time, peak current and energy in
the inductor build according to
where Vd is the diode drop,
TON
L
RON= Switch turn-on resistance, RS= Inductor
DC resistance
TON = Switch ON time
In the discontinuous mode, the switching frequency (Fsw) is
Fsw =
2 * (L) * (VOUT + VD − VIN) * (IOUT)
1/15/2005 Rev.2.10
VIN 2 × TON 2
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 that
the maximum current rating of the SS6642 and
the inductor are not exceeded at the other worstcase 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.
Minimum and maximum input voltage, output
voltage and output current must be established
in advance and then the inductor can be selected.
 VIN  1 VIN
IOB = 
* TON * (1 − x )
* *
 VOUT  2 L
x = (RON + RS ) *
Inductor Selection
(1 + x )
RON + Rs
 VIN  

IPK = 
* TON) 
 * 1 − exp( −
L
 RON + Rs  

x
 VIN 

≅
 * (TON) * 1 − 
2
 L 

≅
VIN
TON
L
(simple loss equation),
where x = (RON + RS ) *
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TON
L
18 of 22
SS6642G
EL =
1
L × Ipk 2
2
When loading is over IOB, the PFM controller
operates in continuous mode. Inductor peak
current can be derived from
The power supplied by the inductor per
cycle must be equal to or greater than
PL/fSW = (VOUT + VD − VIN) * (IOUT) * (
1
)
fsw
 x
 VOUT+ VD − VSW x 
 VIN− VSW
IPK = 
−  * IOUT+ 
 * TON * 1− 
V
V
2
IN
SW
2L
−
 2




in order for the converter to regulate the output.
Valley current (Iv) is
 VOUT+ VD − VSW x 
 VIN− VSW
 x
IV = 
−  * IOUT− 
 * TON* 1− 
2L 
2
 VIN− VSW

 2
Table 1 Indicates resistance and height for each coil.
Power Inductor Type
Coilcraft SMT Type
DS1608
(www.coilcraft.com)
DO3316
Sumida SMT Type CD54
Hold SMT Type PM54
Hold SMT Type PM75
Inductance
( µH )
Rated Current
Height
(A)
(mm)
22
0.10
0.7
47
0.18
0.5
100
0.38
0.3
22
0.08
2.7
47
0.14
1.8
47
0.25
0.7
100
0.50
0.5
47
0.25
0.7
100
0.50
0.5
33
0.11
1.2
Capacitor Selection
A poor choice for an output capacitor can result
in poor efficiency and high output ripple. Ordinary
aluminum electrolytics, 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 types. Tantalum capacitors provide
still better performance but are more expensive.
OSCON capacitors have extremely low ESR and
small size. If capacitance is reduced, output ripple will increase.
1/15/2005 Rev.2.10
Resistance ( Ω )
2.9
5.2
4.5
4.5
5.0
Most of the input supply is applied to the input
bypass capacitor, so 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 the
three main considerations in selecting a rectifier
diode. Best performance is obtained with Schottky
rectifier diodes such as the 1N5819. SSC also has
Schottkies for surface-mount. For lower output
power a 1N4148 can be used, although efficiency
and start-up voltage will suffer substantially.
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19 of 22
SS6642G
The power dissipated in the MOSFET switch is
Component Power Dissipation
Operating in discontinuous mode, power loss in
the winding resistance of the inductor can be
approximated to
PD L =
2  TON 
 VOUT + VF 
 * (POUT )
 * (RD ) * 

3 L 
 VOUT 
where POUT=VOUT * IOUT; RS=Inductor DC R;
PDSW =
2  TON 
 VOUT + VD − VIN 
 * (POUT )
 * (RON) * 

3 L 
VOUT


The power dissipated in the rectifier diode is
 VD 
PDd = 
 * (POUT )
 VOUT 
VD = Diode drop.
1/15/2005 Rev.2.10
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20 of 22
SS6642G
PHYSICAL DIMENSIONS
(unit: mm)
All package options are Pb-free, RoHS compliant.
SOT-23 (GU)
D
0.25
E1
E
c
L
e
θ
L1
e1
A2
A
A1
b
SYMBOL
MIN
MAX
A
0.95
1.45
A1
0.05
0.15
A2
0.90
1.30
b
0.30
0.50
c
0.08
0.22
D
2.80
3.00
E
2.60
3.00
E1
1.50
1.70
e
0.95 BSC
e1
1.90 BSC
L
0.30
L1
0.60
0.60 REF
θ
0˚
8˚
SOT-89 (GX)
D
A
SYMBOL
MIN
MAX
C
A
1.40
1.60
B
0.44
0.56
B1
0.36
0.48
C
0.35
0.44
D
4.40
4.60
D1
1.50
1.83
E
2.29
2.60
D1
H
E
L
B
e
e1
1/15/2005 Rev.2.10
B1
e
1.50 BSC
e1
3.00 BSC
H
3.94
4.25
L
0.89
1.20
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21 of 22
SS6642G
TO-92 (GZ)
SYMBOL
MIN
MAX
A
4.32
5.33
b
0.36
0.47
D
4.45
5.20
E
3.18
4.19
e
2.42
2.66
e1
1.15
1.39
j
3.43
-
L
12.70
-
S
2.03
2.66
A
D
b
S
E
L
j
e1
e
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
use. Silicon Standard reserves the right to make changes as it deems necessary to any products described herein for any reason, including
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
Silicon Standard Corporation or any third parties.
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