TI PT6644

PT6640 Series
24W 12V Input Positive to Negative
Voltage Converter
SLTS037A
(Revised 6/30/2000)
The PT6640 series is a positive
input to negative output line of
Integrated Switching Regulators
(ISRs). Designed for general purpose
applications, the PT6640 series delivers 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.
• Wide Input Voltage Range:
+8V to +25V
• Negative Output:
–2.5V/4A to –15V/1.5A
• Adjustable Output Voltage
• 85% Efficiency
• Remote Sense Capability
Pin-Out Information
Standard Application
4,5,6
C1
PT6640
11,12,13
+
-VOUT
7,8,9,10
1
C2
LOAD
+
VIN
COM
COM
REMOTE SENSE
C 1 = Required 560µF electrolytic
C 2 = Required 330µF electrolytic
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Remote Sense
Do Not Connect
Do Not Connect
+Vin
+Vin
+Vin
–Vout
–Vout
–Vout
–Vout
GND
GND
GND
Vout Adjust
Ordering Information
PT Series Suffix (PT1234X)
PT6641
PT6642
PT6643
PT6644
PT6645
PT6646
Case/Pin
Configuration
= –3.3 Volts
= –5.0 Volts
= –12.0 Volts
= –9.0 Volts
= –15.0 Volts
= –2.5 Volts
Heat
Spreader
Vertical Through-Hole
Horizontal Through-Hole
Horizontal Surface Mount
Pkg Style 400
P
D
E
Note: Back surface
of product is
conducting metal
PT6640
Specifications
PT6640 SERIES
Characteristics
(Ta = 25°C unless noted)
Symbols
Conditions
Min
Typ
Output Current
Io
Ta = 60°C, 200 LFM, pkg P
Ta = 25°C, natural convection Vo≤ – 5.0V
Vo= – 9.0V
Vo= – 12.0V
Vo= – 15.0V
0.1
0.1
0.1
0.1
0.1
—
—
—
—
—
0.1A ≤ I o ≤ Io max
+8
+8
+8
+8
+8
Input Voltage Range
Vin
Vo = –2.5V/3.3V
Vo = – 5.0V
Vo = – 9.0V
Vo = – 12.0V
Vo = – 15.0V
Output Voltage Tolerance
∆Vo
Over Vin range
Ta = -40°C to +65°C
Output Voltage Adjust Range
Voadj
Pin 14 to V o or ground
Vo = – 2.5V
Vo = – 3.3V
Vo = – 5.0V
Vo = – 9.0V
Vo = –12.0V
Vo = –15.0V
Max
Units
(See Note 2)
4.0
2.5
2.0
1.5
A
—
—
—
—
—
+27
+25
+21
+18
+15
V
Vo-0.1
—
Vo+0.1
V
–1.8
–2.2
–3.0
–6.0
–9.0
–10.0
—
—
—
—
—
—
–4.3
–4.7
–6.5
–10.2
–13.6
–17.0
V
Line Regulation
Regline
+9V≤Vin≤+V inmax, I o = Iomax
—
±0.5
±1.0
%Vo
Load Regulation
Regload
Vin = +12V, 0.1≤ Io≤Io max
—
±0.5
±1.0
%Vo
Vo Ripple/Noise
Vn
Vin = +12V, Io = Io max
—
3.0
—
%Vo
Transient Response
with C 2 = 330µF
ttr
Vos
Io step between 0.5xIomax and I omax
Vo over/undershoot
—
—
200
100
—
—
µSec
mV
Efficiency
η
Vin = +12V, Io = 0.5x Io max
Vo = – 2.5V
Vo = – 3.3V
Vo = – 5.0V
Vo = –9.0/12.0V
Vo = –15.0V
—
—
—
—
—
75
79
83
85
84
—
—
—
—
—
%
Vo = – 2.5V
Vo = – 3.3V
Vo = – 5.0V
Vo = –9.0/12.0/15.0V
—
—
—
—
74
77
80
84
—
—
—
—
%
Vin = +12V, I o = I omax
Continued
For technical support and more information, see inside back cover or visit www.ti.com/powertrends
PT6640 Series
24W 12V Input Positive to Negative
Voltage Converter
Specifications (continued)
PT6640 SERIES
Characteristics
(Ta = 25°C unless noted)
Symbols
Conditions
Min
Typ
Max
Switching Frequency
ƒo
+9V ≤ Vin ≤ V inmax
Over Io range
500
550
600
Absolute Maximum
Operating Temperature Range
Ta
Over V in range
-40
—
+85
Storage Temperature
Ts
—
-40
—
+125
°C
—
500
—
G’s
Units
kHz
(2)
°C
Mechanical Shock
—
Per Mil-STD-883D, Method 2002.3
Mechanical Vibration
—
Per Mil-STD-883D, Method 2007.2,
20-2000 Hz, soldered in a PC board
—
7.5
—
G’s
Weight
—
—
—
14
—
grams
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
Characteristic Curves @12.0V Vin
C H A R A C T E R I S T I C S
Safe Operating Area Curves
(See Note A)
Efficiency vs Output Current
PT6642, @Vin =12V
90.0
80.0
PT6643
PT6642
75.0
PT6641
PT6646
70.0
65.0
60.0
Ambient Temperature ( C)
90.0
85.0
Efficiency (%)
(See Note B)
80.0
70.0
Airflow
60.0
200LFM
120LFM
50.0
60LFM
Nat conv
40.0
30.0
20.0
0
0.5
1
1.5
2
2.5
3
3.5
4
0.0
Output Current (A)
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Output Current (A)
Ripple vs Output Current
150
Ripple (mV)
125
100
PT6645
PT6643
75
PT6644
PT6642
50
PT6641
PT6646
25
0
0
0.5
1
1.5
2
2.5
3
3.5
4
Output Current (A)
Power Dissipation vs Output Current
6
PDiss (Watts)
5
PT6645
4
PT6643
3
PT6644
PT6642
2
PT6641
PT6646
1
0
0
0.5
1
1.5
2
2.5
3
3.5
4
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. Table 1 gives the allowable adjustment range for each model in the series as Va (min)
and Va (max).
Figure 1
+V in
4,5,6
PT6640
+V in
GND
11,12,13
C in
5 6 0µF
7,8,9,10
V out
SNS(+)
1
V
14
R2
|-V o | Up
+
+
Adjust Up:
An increase in the negative output
voltage is obtained by adding a resistor R2, between pin
14 (Vo adjust) and pins 7-10 (-Vout).
out
V o(adj)
C out
3 3 0µF
L
O
A
D
(R1)
|-V o | Down
COM
COM
Adjust Down:
Adding a resistor (R1), between pin 14
(Vo adjust) and pins 11-13 (GND), decreases the output
voltage magnitude.
Refer to Figure 1 and Table 2 for both the placement and
value of the required resistor, either (R1) or R2 as appropriate.
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 Vo adjust to either GND,
Vout, or the Remote Sense pin. Any capacitance added to
the Vo 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 (Vo adjust) and pin 1 (Remote
Sense) can benefit load regulation.
4. The maximum allowed input voltage (Vin) will change as
Vout is adjusted. The difference between the input voltage
(Vin) and the output voltage (Vout) must not exceed 30V or
10 × Vout, whichever is less. Use one of the following
formulas to determine the maximum allowed input voltage
for the PT6640.
Vout greater than 2.73V,
= 30 – Vout
Vin(max)
The values of (R1) [adjust down], and R2 [adjust up], can
also be calculated using the following formulas.
(R1)
=
Ro (Vo – 1.25)(Va – 1.25)
1.25 (Vo – Va)
R2
=
Ro (Vo – 1.25)
Va - Vo
Where: Vo
Va
Ro
Rs
– Rs
= Original Vout (magnitude)
= Adjusted Vout (magnitude)
= The resistance value in Table 1
= The series resistance from Table 1
Vdc
For example, if Vout = -12V,
Vin(max)
= 30 – -12 = 18Vdc
Vout less than 2.73V,
= 10 × Vout
Vin(max)
Vdc
Table 1
PT6640 ADJUSTMENT AND FORMULA PARAMETERS
Series Pt #
PT6646
PT6641
PT6642
PT6644
PT6643
Vo (nom)
–2.5V
–3.3V
–5.0V
–9.0V
–12.0V
–15.0V
Va (min)
–1.8V
–2.2V
–3.0V
–6.0V
–9.0V
–10.0V
Va (max)
–4.3V
–4.7V
–6.5V
–10.2V
–13.6V
–17.0V
Ro (kΩ
Ω)
4.99
4.22
2.49
2.0
2.0
2.0
Ω)
Rs (kΩ
2.49
4.99
4.99
12.7
12.7
12.7
For technical support and more information, see inside back cover or visit www.ti.com/powertrends
– Rs
PT6645
kΩ
kΩ
Application Notes continued
PT6640 Series
Table 2
PT6640 ADJUSTMENT RESISTOR VALUES
Series Pt #
Current
Vo (nom)
Va (req’d)
PT6646
4Adc
–2.5Vdc
PT6641
4Adc
–3.3Vdc
PT6642
4Adc
–5.0Vdc
Series Pt #
Current
Vo (nom)
Va (req’d)
PT6644
2.5Adc
–9.0Vdc
–1.8
(1.4)kΩ
–6.0
–1.9
(2.9)kΩ
–6.2
(9.2)kΩ
–2.0
(5.0)kΩ
–6.4
(11.9)kΩ
PT6645
1.5Adc
–15.0Vdc
(6.9)kΩ
–2.1
(8.1)kΩ
–6.6
(14.0)kΩ
–2.2
(13.3)kΩ
(1.0)kΩ
–6.8
(18.6)kΩ
–2.3
(23.7)kΩ
(2.3)kΩ
–7.0
(23.0)kΩ
–2.4
(54.9)kΩ
(3.9)kΩ
–7.2
(28.3)kΩ
(5.8)kΩ
–7.4
(35.0)kΩ
–2.5
PT6643
2Adc
–12.0Vdc
–2.6
59.9kΩ
(8.4)kΩ
–7.6
(43.5)kΩ
–2.7
28.7kΩ
(11.7)kΩ
–7.8
(55.0)kΩ
–2.8
18.3kΩ
(16.5)kΩ
–8.0
(71.0)kΩ
–2.9
13.1kΩ
(23.6)kΩ
–8.2
(95.0)kΩ
–3.0
10.0kΩ
(35.4)kΩ
(1.6)kΩ
–8.4
(135.0)kΩ
–3.1
7.9kΩ
(59.0)kΩ
(2.3)kΩ
–8.6
(215.0)kΩ
–3.2
6.4kΩ
(130.0)kΩ
(3.1)kΩ
–8.8
(455.0)kΩ
–3.3
5.3kΩ
(4.0)kΩ
–9.0
–3.4
4.4kΩ
81.5kΩ
(5.1)kΩ
–9.2
64.8kΩ
(36.1)kΩ
–3.5
3.8kΩ
38.3kΩ
(6.2)kΩ
–9.4
26.1kΩ
(41.2)kΩ
–3.6
3.2kΩ
23.8kΩ
(7.6)kΩ
–9.6
13.1kΩ
(47.1)kΩ
–3.7
2.7kΩ
16.6kΩ
(9.1)kΩ
–9.8
6.7kΩ
(54.1)kΩ
–3.8
2.3kΩ
12.3kΩ
(10.9)kΩ
–10.0
2.8kΩ
(62.6)kΩ
(25.8)kΩ
–3.9
2.0kΩ
9.4kΩ
(13.0)kΩ
–10.2
0.2kΩ
(72.8)kΩ
(28.3)kΩ
–4.0
1.7kΩ
7.4kΩ
(15.6)kΩ
–10.4
(85.7)kΩ
(31.1)kΩ
–4.1
1.4kΩ
5.8kΩ
(18.7)kΩ
–10.6
(102.0)kΩ
(34.1)kΩ
–4.2
1.2kΩ
4.6kΩ
(22.6)kΩ
–10.8
(124.0)kΩ
(37.3)kΩ
–4.3
1.0kΩ
3.7kΩ
(27.6)kΩ
–11.0
(155.0)kΩ
(40.9)kΩ
–4.4
2.9kΩ
(34.2)kΩ
–11.2
(201.0)kΩ
(44.9)kΩ
–4.5
2.2kΩ
(43.6)kΩ
–11.4
(278.0)kΩ
(49.3)kΩ
–4.6
1.7kΩ
(57.6)kΩ
–11.6
(432.0)kΩ
(54.3)kΩ
–4.7
1.2kΩ
(80.9)kΩ
–11.8
(895.0)kΩ
–4.8
(128.0)kΩ
–12.0
–4.9
(268.0)kΩ
–5.0
(31.7)kΩ
(59.8)kΩ
(66.1)kΩ
–12.2
94.8kΩ
(73.3)kΩ
–12.4
41.1kΩ
(81.6)kΩ
–5.1
88.4kΩ
–12.6
23.1kΩ
(91.3)kΩ
–5.2
41.7kΩ
–12.8
14.2kΩ
(103.0)kΩ
–5.3
26.1kΩ
–13.0
8.8kΩ
(117.0)kΩ
–5.4
18.4kΩ
–13.2
5.2kΩ
(133.0)kΩ
–5.5
13.7kΩ
–13.4
2.7kΩ
(154.0)kΩ
–5.6
10.6kΩ
–13.6
0.7kΩ
(181.0)kΩ
–5.7
8.4kΩ
–13.8
(217.0)kΩ
–5.8
6.7kΩ
–14.0
(268.0)kΩ
–5.9
5.4kΩ
–14.2
(343.0)kΩ
–6.0
4.4kΩ
–14.5
(570.0)kΩ
–6.1
3.5kΩ
–15.0
–6.2
2.8kΩ
–15.5
42.3kΩ
–6.3
2.2kΩ
–16.0
14.8kΩ
–6.4
1.7kΩ
–16.5
5.6kΩ
1.2kΩ
–17.0
1.1kΩ
–6.5
R1 = (Blue)
R2 = Black
For technical support and more information, see inside back cover or visit www.ti.com/powertrends
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Copyright 
2000, Te xas Instrume nts Incorporate d
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