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PT6640 Series
24W 12V Input Positive to Negative
Voltage Converter
SLTS037A
(Revised 6/30/2000)
•
Wide Input Voltage Range:
+8V to +25V
•
Negative Output:
–2.5V/4A to –15V/1.5A
•
Adjustable Output Voltage
•
85% Efficiency
•
Remote Sense Capability
The PT6640 series is a positive
input to negative output line of
Integrated Switching Regulators
(ISRs). Designed for general purpose
applications, the PT6640 series deliv-
ers a negative output voltage at up
to 24W. The PT6640 is packaged in
a 14-Pin SIP (Single In-line Package)
and is available in a surface-mount
configuration.
Pin-Out Information
Standard Application
V
IN
4,5,6
Ordering Information
PT6641
PT6642
PT6643
PT6644
PT6645
PT6646
= –3.3 Volts
= –5.0 Volts
= –12.0 Volts
= –9.0 Volts
= –15.0 Volts
= –2.5 Volts
PT Series Suffix
(PT1234X)
Case/Pin
Configuration
Vertical Through-Hole
Horizontal Through-Hole
Horizontal Surface Mount
Heat
Spreader
PT6640
11,12,13
1
7,8,9,10
-V
OUT
COM
REMOTE SENSE
C
1
= Required 560µF electrolytic
C
2
= Required 330µF electrolytic
Specifications
Characteristics
(T
a
= 25°C unless noted)
Output Current
Input Voltage Range
Output Voltage T
olerance
Output Voltage Adjust Range
Line Regulation
Load Regulation
V
o
Ripple/Noise
Transient Response
with C
2
= 330µF
Efficiency
For technical support and more information, see inside back cover or visit www.ti.com/powertrends
+
C
1
+
C
2
LOAD
COM
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Remote Sense
Do Not Connect
Do Not Connect
+V
in
+V
in
+V
in
–
V
out
–
V
out
–
V
out
–
V
out
GND
GND
GND
V
out
Adjust
P
D
E
Pkg Style 400
PT6640
Note: Back surface
of product is
conducting metal
PT6640 SERIES
Symbols
I
o
Conditions
T
a
= 60°C, 200 LFM, pkg P
T
a
= 25°C, natural convection V
o
≤
– 5.0V
V
o
= – 9.0V
V
o
= – 12.0V
V
o
= – 15.0V
0.1A
≤
I
o
≤
I
o
max
V
o
= –2.5V/3.3V
V
o
= – 5.0V
V
o
= – 9.0V
V
o
= – 12.0V
V
o
= – 15.0V
Min
0.1
0.1
0.1
0.1
0.1
+8
+8
+8
+8
+8
V
o
-0.1
V
o
= – 2.5V
V
o
= – 3.3V
V
o
= – 5.0V
V
o
= – 9.0V
V
o
= –12.0V
V
o
= –15.0V
–1.8
–2.2
–3.0
–6.0
–9.0
–10.0
—
—
—
—
—
—
—
—
—
—
—
—
—
—
Typ
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
±0.5
±0.5
3.0
200
100
75
79
83
85
84
74
77
80
84
Max
(See Note 2)
Units
4.0
2.5
2.0
1.5
+27
+25
+21
+18
+15
V
o
+0.1
–4.3
–4.7
–6.5
–10.2
–13.6
–17.0
±1.0
±1.0
—
—
—
—
—
—
—
—
—
—
—
—
A
V
in
V
∆V
o
V
oadj
Over V
in
range
T
a
= -40°C to +65°C
Pin 14 to V
o
or ground
V
V
Reg
line
Reg
load
V
n
t
tr
V
os
η
+9V≤V
in
≤+V
in
max, I
o
= I
o
max
V
in
= +12V, 0.1≤ I
o
≤I
o
max
V
in
= +12V, I
o
= I
o
max
I
o
step between 0.5xI
o
max and I
o
max
V
o
over/undershoot
V
in
= +12V, I
o
= 0.5x I
o
max
V
o
= – 2.5V
V
o
= – 3.3V
V
o
= – 5.0V
V
o
= –9.0/12.0V
V
o
= –15.0V
%V
o
%V
o
%V
o
µSec
mV
%
V
in
= +12V, I
o
= I
o
max
V
o
= – 2.5V
V
o
= – 3.3V
V
o
= – 5.0V
V
o
= –9.0/12.0/15.0V
%
Continued
PT6640 Series
24W 12V Input Positive to Negative
Voltage Converter
Specifications
(continued)
Characteristics
(T
a
= 25°C unless noted)
Switching Frequency
Absolute Maximum
Operating T
emperature Range
Storage T
emperature
Mechanical Shock
Mechanical Vibration
Weight
PT6640 SERIES
Symbols
ƒ
o
T
a
T
s
—
—
—
Conditions
+9V
≤
V
in
≤
V
in
max
Over I
o
range
Over V
in
range
—
Per Mil-STD-883D, Method 2002.3
Per Mil-STD-883D, Method 2007.2,
20-2000 Hz, soldered in a PC board
—
Min
500
-40
-40
—
—
—
Typ
550
—
—
500
7.5
14
Max
600
+85
(2)
Units
kHz
°C
°C
G’s
G’s
grams
+125
—
—
—
Notes:
(1) The PT6640 Series requires a 330µF(output) and 560µF(input) electrolytic capacitors for proper operation in all applications.
(2) See Safe Operating Area curves or call the factory for guidance on thermal derating.
T Y P I C A L
C H A R A C T E R I S T I C S
Characteristic Curves @12.0V V
in
Efficiency vs Output Current
90.0
85.0
80.0
75.0
70.0
65.0
60.0
0
0.5
1
1.5
2
2.5
3
3.5
4
(See Note A)
Safe Operating Area Curves
PT6642, @V
in
=12V
90.0
80.0
70.0
(See Note B)
Ambient Temperature ( C)
Efficiency (%)
Airflow
60.0
50.0
40.0
30.0
20.0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
200LFM
120LFM
60LFM
Nat conv
PT6643
PT6642
PT6641
PT6646
Output Current (A)
Output Current (A)
Ripple vs Output Current
150
125
100
75
50
25
0
0
0.5
1
1.5
2
2.5
3
3.5
4
Ripple (mV)
PT6645
PT6643
PT6644
PT6642
PT6641
PT6646
Output Current (A)
Power Dissipation vs Output Current
6
5
PDiss (Watts)
4
3
2
1
0
0
0.5
1
1.5
2
2.5
3
3.5
4
PT6645
PT6643
PT6644
PT6642
PT6641
PT6646
Output Current (A)
Note A:
Characteristic data has been developed from actual products tested at 25°C. This data is considered typical data for the DC-DC Converter.
Note B:
SOA curves represent operating conditions at which internal components are at or below manufacturer’s maximum rated operating temperatures.
For technical support and more information, see inside back cover or visit www.ti.com/powertrends
Application Notes
PT6640 Series
Adjusting the Output Voltage of the PT6640 24W
Positive to Negative ISR Series
The negative output voltage of the Power Trends
PT6640 series ISRs may be adjusted higher or lower than
the factory trimmed pre-set voltage with the addition of a
single external resistor. T
able 1 gives the allowable ad-
justment range for each model in the series as V
a
(min)
and V
a
(max).
Adjust Up:
An increase in the negative output
voltage is obtained by adding a resistor R2, between pin
14 (V
o
adjust) and pins 7-10 (-V
out
).
Figure 1
+V
in
4,5,6
+V in
PT6640
GND
11,12,13
SNS(+)
1
V out
7,8,9,10
V
out
V
o
(adj)
14
C
in
5 6 0µF
+
R2
|-V
o
| Up
+
C
out
3 3 0µF
L
O
A
D
(R1)
|-V
o
| Down
COM
COM
Adjust Down:
Adding a resistor (R1), between pin 14
(V
o
adjust) and pins 11-13 (GND), decreases the output
voltage magnitude.
Refer to Figure 1 and T
able 2 for both the placement and
value of the required resistor, either (R1) or R2 as appro-
priate.
Notes:
1. Use only a single 1% resistor in either the
(R1)
or R2
location. Place the resistor as close to the ISR as possible.
2. Never connect capacitors from V
o
adjust to either GND,
V
out
, or the Remote Sense pin. Any capacitance added to
the V
o
adjust pin will affect the stability of the ISR.
3. If the Remote Sense feature is being used, connecting the
resistor
(R1)
between pin 14 (V
o
adjust) and pin 1 (Remote
Sense) can benefit load regulation.
4. The maximum allowed input voltage (V
in
) will change as
V
out
is adjusted. The difference between the input voltage
(V
in
) and the output voltage (V
out
) must not exceed 30V or
10
×
V
out
, whichever is less. Use one of the following
formulas to determine the maximum allowed input voltage
for the PT6640.
V
out
greater than 2.73V
,
= 30 –
V
out
V
in
(max)
Vdc
The values of
(R1)
[adjust down], and R2 [adjust up], can
also be calculated using the following formulas.
R
o
(V
o
– 1.25)(V
a
– 1.25)
1.25 (V
o
– V
a
)
(R1)
=
– R
s
k
Ω
R2
=
R
o
(V
o
– 1.25)
V
a
- V
o
– R
s
k
Ω
Where: V
o
V
a
R
o
R
s
= Original V
out
(magnitude)
= Adjusted V
out
(magnitude)
= The resistance value in T
able 1
= The series resistance from T
able 1
,
For example, if V
out
= -12V
V
in
(max)
= 30 –
-12
= 18Vdc
,
V
out
less than 2.73V
= 10
× V
out
V
in
(max)
Vdc
Table 1
PT6640 ADJUSTMENT AND FORMULA PARAMETERS
Series Pt #
Vo (nom)
Va (min)
Va (max)
Ro (kΩ)
Ω
Rs (kΩ)
Ω
PT6646
–2.5V
–1.8V
–4.3V
4.99
2.49
PT6641
–3.3V
–2.2V
–4.7V
4.22
4.99
PT6642
–5.0V
–3.0V
–6.5V
2.49
4.99
PT6644
–9.0V
–6.0V
–10.2V
2.0
12.7
PT6643
–12.0V
–9.0V
–13.6V
2.0
12.7
PT6645
–15.0V
–10.0V
–17.0V
2.0
12.7
For technical support and more information, see inside back cover or visit www.ti.com/powertrends
Application Notes
continued
PT6640 Series
Table 2
PT6640 ADJUSTMENT RESISTOR VALUES
Series Pt #
Current
V
o
(nom)
V
a
(req’d)
–1.8
–1.9
–2.0
–2.1
–2.2
–2.3
–2.4
–2.5
–2.6
–2.7
–2.8
–2.9
–3.0
–3.1
–3.2
–3.3
–3.4
–3.5
–3.6
–3.7
–3.8
–3.9
–4.0
–4.1
–4.2
–4.3
–4.4
–4.5
–4.6
–4.7
–4.8
–4.9
–5.0
–5.1
–5.2
–5.3
–5.4
–5.5
–5.6
–5.7
–5.8
–5.9
–6.0
–6.1
–6.2
–6.3
–6.4
–6.5
R1 =
(Blue)
R2 = Black
88.4kΩ
41.7kΩ
26.1kΩ
18.4kΩ
13.7kΩ
10.6kΩ
8.4kΩ
6.7kΩ
5.4kΩ
4.4kΩ
3.5kΩ
2.8kΩ
2.2kΩ
1.7kΩ
1.2kΩ
59.9kΩ
28.7kΩ
18.3kΩ
13.1kΩ
10.0kΩ
7.9kΩ
6.4kΩ
5.3kΩ
4.4kΩ
3.8kΩ
3.2kΩ
2.7kΩ
2.3kΩ
2.0kΩ
1.7kΩ
1.4kΩ
1.2kΩ
1.0kΩ
81.5kΩ
38.3kΩ
23.8kΩ
16.6kΩ
12.3kΩ
9.4kΩ
7.4kΩ
5.8kΩ
4.6kΩ
3.7kΩ
2.9kΩ
2.2kΩ
1.7kΩ
1.2kΩ
PT6646
4Adc
–2.5Vdc
(1.4)kΩ
(2.9)kΩ
(5.0)kΩ
(8.1)kΩ
(13.3)kΩ
(23.7)kΩ
(54.9)kΩ
(1.0)kΩ
(2.3)kΩ
(3.9)kΩ
(5.8)kΩ
(8.4)kΩ
(11.7)kΩ
(16.5)kΩ
(23.6)kΩ
(35.4)kΩ
(59.0)kΩ
(130.0)kΩ
(1.6)kΩ
(2.3)kΩ
(3.1)kΩ
(4.0)kΩ
(5.1)kΩ
(6.2)kΩ
(7.6)kΩ
(9.1)kΩ
(10.9)kΩ
(13.0)kΩ
(15.6)kΩ
(18.7)kΩ
(22.6)kΩ
(27.6)kΩ
(34.2)kΩ
(43.6)kΩ
(57.6)kΩ
(80.9)kΩ
(128.0)kΩ
(268.0)kΩ
PT6641
4Adc
–3.3Vdc
PT6642
4Adc
–5.0Vdc
Series Pt #
Current
V
o
(nom)
V
a
(req’d)
–6.0
–6.2
–6.4
–6.6
–6.8
–7.0
–7.2
–7.4
–7.6
–7.8
–8.0
–8.2
–8.4
–8.6
–8.8
–9.0
–9.2
–9.4
–9.6
–9.8
–10.0
–10.2
–10.4
–10.6
–10.8
–11.0
–11.2
–11.4
–11.6
–11.8
–12.0
–12.2
–12.4
–12.6
–12.8
–13.0
–13.2
–13.4
–13.6
–13.8
–14.0
–14.2
–14.5
–15.0
–15.5
–16.0
–16.5
–17.0
42.3kΩ
14.8kΩ
5.6kΩ
1.1kΩ
94.8kΩ
41.1kΩ
23.1kΩ
14.2kΩ
8.8kΩ
5.2kΩ
2.7kΩ
0.7kΩ
64.8kΩ
26.1kΩ
13.1kΩ
6.7kΩ
2.8kΩ
0.2kΩ
PT6644
2.5Adc
–9.0Vdc
(6.9)kΩ
(9.2)kΩ
(11.9)kΩ
(14.0)kΩ
(18.6)kΩ
(23.0)kΩ
(28.3)kΩ
(35.0)kΩ
(43.5)kΩ
(55.0)kΩ
(71.0)kΩ
(95.0)kΩ
(135.0)kΩ
(215.0)kΩ
(455.0)kΩ
(31.7)kΩ
(36.1)kΩ
(41.2)kΩ
(47.1)kΩ
(54.1)kΩ
(62.6)kΩ
(72.8)kΩ
(85.7)kΩ
(102.0)kΩ
(124.0)kΩ
(155.0)kΩ
(201.0)kΩ
(278.0)kΩ
(432.0)kΩ
(895.0)kΩ
(25.8)kΩ
(28.3)kΩ
(31.1)kΩ
(34.1)kΩ
(37.3)kΩ
(40.9)kΩ
(44.9)kΩ
(49.3)kΩ
(54.3)kΩ
(59.8)kΩ
(66.1)kΩ
(73.3)kΩ
(81.6)kΩ
(91.3)kΩ
(103.0)kΩ
(117.0)kΩ
(133.0)kΩ
(154.0)kΩ
(181.0)kΩ
(217.0)kΩ
(268.0)kΩ
(343.0)kΩ
(570.0)kΩ
PT6643
2Adc
–12.0Vdc
PT6645
1.5Adc
–15.0Vdc
For technical support and more information, see inside back cover or visit www.ti.com/powertrends
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