SM645/SM646/SM647
SWITCHING REGULATOR
POWER OUTPUT STAGES
DESCRIPTION
The SM645/646/647 series of Power Output Stages are espe-
cially designed to be driven with standard PWM integrated
circuits to form an efficient switching power supply. The SM645,
SM646 and SM647 are optimized for non-isolated Buck and
Buck-Boost application. The hybrid circuit construction utilizes
thick film resistors on a beryllia substrate for maximum thermal
conductivity and resultant low thermal impedance. All of the
active elements in the hybrid are fully passivated.
FEATURES
•
Equivalent to the Unitrode PIC 645, 646, 647
•
15A current capability
•
Cost saving design reduces size, improves efficiency,
reduces noise and RFI
•
High operating frequency (to > 100KHz) results in
smaller inductor-capacitor filter and improved power
supply response time
•
High operating efficiency at 7A typical performance -
Rise and fall time < 300ns
Efficiency > 85%
HIGH RELIABILITY FEATURES
♦
Available with high reliability processing
FUNCTIONAL DIAGRAM
SM645/SM646/SM647
4/90 Rev 1.1 2/94
Copyright
©
1994
1
11861 Western Avenue
∞
Garden Grove, CA 92841
(714) 898-8121
∞
FAX: (714) 893-2570
L
INFINITY
Microelectronics Inc.
SM645/SM646/SM647
ABSOLUTE MAXIMUM RATINGS
(Note 1)
SM645
Input Voltage, V
4 - 2
......................................... 60V
Output Voltage, V
1 - 2
...................................... 60v
5V
Drive Input Reverse Voltage, V
3 - 4
................
Continuous Output Current, I
1
....................... 15A
Peak Output Current ..................................... 20A
Drive Current, I
3
............................................ -0.4A
SM646
80V
80v
5V
15A
20A
-0.4A
SM647
100V
100V
5V
15A
20A
-0.4A
Thermal Resistance
Power Switch,
θ
J - C
................................................... 2.0°C/W
Commutating Diode ................................................. 2.0°C/W
Case to Ambient,
θ
C - A
............................................ 30.0°C/W
Note 1. Exceeding these ratings could cause damage to the device.
Operating Junction Temperature
Hermetic (K Package) .................................................. 150°C
Storage Temperature Range ............................. -65°C to 150°C
Lead Temperature (Soldering, 10 Seconds) ................... 300°C
THERMAL DATA
K Package:
Thermal Resistance-
Junction to Case
,
θ
JC
.................. 2.0°C/W
Thermal Resistance-
Junction to Ambient
,
θ
JA
.............. 35°C/W
Note A. Junction Temperature Calculation: T
J
= T
A
+ (P
D
x
θ
JA
).
Note B. The above numbers for
θ
JC
are maximums for the limiting
thermal resistance of the package in a standard mount-
ing configuration. The
θ
JA
numbers are meant to be
guidelines for the thermal performance of the device/pc-
board system. All of the above assume no ambient
airflow.
RECOMMENDED OPERATING CONDITIONS
(Note 2)
Input Voltage, V
4 - 2
..........................................
Output Voltage, V
1 - 2
.......................................
Drive Input Reverse Voltage, V
3 - 4
..................
Output Current, I
1
...........................................
Drive Current, I
3
..............................................
SM645
50V
50v
4V
13A
-0.3A
SM646
70V
70v
4V
13A
-0.3A
SM647
90V
90V
4V
13A
-0.3A
Operating Ambient Temperature Range
SM6XXK ....................................................... 0°C to 70°C
SM6XXHRK ............................................ -55°C to 125°C
Note 2. Range over which the device is functional.
ELECTRICAL CHARACTERISTICS
(Unless otherwise specified, these specifications apply for the operating ambient temperature of T
A
= 25°C. Low duty cycle pulse testing tech-
niques are used which maintains junction and case temperatures equal to the ambient temperature.)
Parameter
On-State Voltage
(Note 3)
Diode Forward Voltage
(Note 3)
Off-State Current
Diode Reverse Current
Test Conditions
I
4
= 7A(-7A), I
3
= -30mA(30mA)
I
4
= 15A(-15A), I
3
= -30mA(30mA)
I
4
= 7A(-7A)
I
4
= 15A(-15A)
V
4
= Rated input voltage
V
4
= Rated input voltage, T
A
= 125°C
V
1
= Rated output voltage
V
1
= Rated output voltage, T
A
= 125°C
SG645/646/647
Min. Typ. Max.
1.0
1.5
2.5
3.5
0.85 1.25
0.95 1.75
0.1
10
10
1.0
10
500
Units
V
V
V
V
µA
µA
µA
µA
Note 3. Pulse test: Duration = 300µs, Duty Cycle
≤
2%.
4/90 Rev 1.1 2/94
Copyright
©
1994
2
11861 Western Avenue
∞
Garden Grove, CA 92841
(714) 898-8121
∞
FAX: (714) 893-2570
L
INFINITY
Microelectronics Inc.
SM645/SM646/SM647
ELECTRICAL CHARACTERISTICS
Parameter
(continued)
Test Conditions
SG645/646/647
Min. Typ. Max.
35
65
40
700
70
175
85
60
150
60
175
300
Units
ns
ns
ns
ns
ns
ns
%
Dynamic Characteristics
(See Figures 1 & 2)
(Notes 4 & 5)
Current Delay Time
Current Rise Time
Voltage Rise Time
Voltage Storage Time
Voltage Fall Time
Current Fall Time
Efficiency
(Note 5)
AC TEST CIRCUIT AND SWITCHING TIME WAVEFORMS
(Note 6)
SM645
SM646
SM647
FIGURE 1 - SM645/646/647 SWITCHING SPEED CIRCUIT
FIGURE 2 - SM645/646/647 SWITCHING WAVEFORMS
Note 4. In switching an inductive load, the current will lead the voltage on turn-on and lag the voltage on turn-off (see Figure 2). Therefore, Voltage
Delay Time (t
DV
)
≅
t
di
+ t
ri
and Current Storage Time (t
si
)
≅
t
sv
+ t
fv
.
Note 5. The efficiency is a measure of internal power losses and is equal to Output Power divided by Input Power. The switching speed circuit of Figure
1, in which the efficiency measured, is represenative of typical operating conditions for the SM600 series switching regulators.
APPLICATION CIRCUITS
SM64X
SM64X
FIGURE 3 - STEP DOWN (BUCK) CONVERTER
FIGURE 4 - NEGATIVE OUTPUT DOWN/UP (BUCK-BOOST) CONVERTER
4/90 Rev 1.1 2/94
Copyright
©
1994
3
11861 Western Avenue
∞
Garden Grove, CA 92841
(714) 898-8121
∞
FAX: (714) 893-2570
L
INFINITY
Microelectronics Inc.
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