TI PT7705

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Application Notes
Mechanical Outline
Product Selector Guide
(800) 531-5782
PT7705
Series
18 AMP “BIG-HAMMER” PROGRAMMABLE
INTEGRATED SWITCHING REGULATOR
The PT7705 is a new series of
high-performance, 18 Amp Integrated
Switching Regulators (ISRs) housed in
a 27-pin SIP package. The 18A capability allows easy integration of the
latest high-speed, low-voltage µPs and
bus drivers into existing 5V systems.
The PT7705 series has been designed to work in parallel with one or
more of the PT7749 - 18A current
boosters for increased Iout in incre-
Revised 5/15/98
ments of 18A.
The output voltage of the PT7705
can be easily programmed from 1.3V
to 3.5V with a 5 bit input compatible
with Intel’s Pentium II Processor.
A differential remote sense is also provided which automatically compensates
for any voltage drop from the ISR to
the load.
1200µF of output capacitance are
required for proper operation.
Pin-Out Information
Standard Application
PROGRAMMING PINS
VID0
VID1
VID2
VID3
VID4
REMOTE SENSE (+)
6 4 3 2 1
L1
VIN
CIN
+
26
PT7705
7 - 11
1µH
27
13 - 19
5
VOUT
20 - 25
12
COUT
+
LOAD
SYNC OUT
GND
GND
STBY*
REMOTE SENSE (-)
Cin = Required 1200µF electrolytic
Cout= Required 1200µF electrolytic
L1 = Optional 1µH input choke
Pin Function
Pin Function
Pin Function
1
VID0
10
Vin
19
GND
2
3
VID1
VID2
11
12
Vin
Remote Sense Gnd
20
21
Vout
Vout
4
5
VID3
STBY* - Stand-by
13
14
GND
GND
22
23
Vout
Vout
6
7
VID4
Vin
15
16
GND
GND
24
25
Vout
Vout
8
9
Vin
Vin
17
18
GND
GND
26
27
Sync Out
Remote Sense Vout
For STBY* pin; open = output enabled; ground = output
disabled.
Specifications
PT7705 SERIES
Characteristics
(Ta = 25°C unless noted)
Symbols
Conditions
Min
Typ
Max
Units
Output Current
Io
Ta = +60°C, 200 LFM, pkg N
Ta = +25°C, natural convection
0.1 *
0.1 *
—
—
18 **
15 **
A
A
Input Voltage Range
Vin
0.1A ≤ Io ≤ 15A
4.5 ***
—
5.5
V
Output Voltage Tolerance
∆Vo
Vin = +5V, Io = 15A
0°C ≤ Ta ≤ +65°C
Vo-0.03
—
Vo+0.03
V
Line Regulation
Regline
4.5V ≤ Vin ≤ 5.5V, Io = 15A
—
±10
—
mV
Load Regulation
Regload
Vin = +5V, 0.1 ≤ Io ≤ 15A
—
±10
—
mV
Vo Ripple/Noise
Vn
Vin = +5V, I o = 15A
—
50
—
mV
Transient Response
with Cout = 1200µF
ttr
Vos
Io step between 7.5A and 15A
Vo over/undershoot
—
—
100
200
—
—
µSec
mV
Efficiency
η
Vin = +5V, Io = 10A
—
—
—
—
—
89
87
85
79
77
—
—
—
—
—
%
%
%
%
%
Switching Frequency
ƒo
4.5V ≤ V in ≤ 5.5V
0.1A ≤ Io ≤ 15A
650
700
750
kHz
Absolute Maximum
Operating Temperature Range
Ta
—
0
—
+85
°C
Recommended Operating
Temperature Range
Ta
Forced Air Flow = 200 LFM
Over Vin and Io Ranges
0
—
+65****
°C
Storage Temperature
Ts
Vo
Vo
Vo
Vo
Vo
= 3.3V
= 2.9V
= 2.5V
= 1.8V
= 1.5V
—
-40
—
+125
°C
Mechanical Shock
Per Mil-STD-883D, Method 2002.3
1 msec, Half Sine, mounted to a fixture
—
500
—
G’s
Mechanical Vibration
Per Mil-STD-883D, Method 2007.2,
20-2000 Hz, Soldered in a PC board
—
10
—
G’s
Vertical/Horizontal
—
31/41
—
grams
Weight
—
* ISR-will operate down to no load with reduced specifications. Please note that this product is not short-circuit protected.
**The PT7705 series can be easily paralleled with one or more of the PT7749 Current Boosters to provide increased output current in increments of 18A.
*** The minimum input voltage is 4.5V or Vout+1.2V, whichever is greater.
****See SOA curves.
Output Capacitors: The PT7705 series requires a minimum ouput capacitance of 1200µF for proper operation. Do not use Oscon type capacitors. The maximum
allowable output capacitance is 15,000µF. See Capacitor Application Note.
Input Filter: An input filter is optional for most applications. The input inductor must be sized to handle 15ADC with a typical value of 1µH. The input capacitance must be
rated for a minimum of 1.3Arms of ripple current. For transient or dynamic load applications, additional capacitance may be required.
38
Power Trends, Inc. 27715 Diehl Road, Warrenville, IL 60555 (800) 531-5782 Fax: (630) 393-6902 http://www.powertrends.com
Features
For assistance or to order, call
(800) 531-5782
PT7705
Series
Ordering Information
Programming Information
VID3 VID2 VID1 VID0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
2.0V
2.1V
2.2V
2.3V
2.4V
2.5V
2.6V
2.7V
2.8V
2.9V
3.0V
3.1V
3.2V
3.3V
3.4V
3.5V
(For dimensions and PC board layout,
see Package Styles 800 and 810.)
1.30V
1.35V
1.40V
1.45V
1.50V
1.55V
1.60V
1.65V
1.70V
1.75V
1.80V
1.85V
1.90V
1.95V
2.00V
2.05V
PT Series Suffix (PT1234X)
Case/Pin
Configuration
Vertical Through-Hole
Horizontal Through-Hole
Horizontal Surface Mount
N
A
C
Logic 0 = Pin 12 potential (remote sense gnd)
Logic 1 = Open circuit (no pull-up resistors)
VID3 and VID4 may not be changed while the unit is operating.
C H A R A C T E R I S T I C
PT7705, Vo = 3.3 VDC
D A T A
PT7705, Vo = 3.3 VDC
(See Note 1)
Safe Operating Area Curves (@Vin=+5V)
(See Note 1)
Efficiency vs Output Current
100
PKG SUFFIX N
Ambient Temperature (°C)
80
70
Airflow
Recommended Maximum
Operating Temperature
60
Efficiency - %
90
90
80
Vin
4.5V
70
5.0V
Nat Conv
5.5V
60
60LFM
100LFM
50
50
200LFM
40
40
0
30
3
6
9
12
15
18
Iout-(Amps)
20
0
2
4
6
8
10
12
14
16
18
Ripple vs Output Current
Output Current (Amps)
60
PKG SUFFIX A, C
50
Vin
40
80
70
Airflow
Recommended Maximum
Operating Temperature
60
Nat Conv
Ripple-(mV)
Ambient Temperature (°C)
90
5.5V
30
5.0V
4.5V
20
60LFM
100LFM
50
10
200LFM
40
0
0
3
30
6
9
12
15
18
Iout-(Amps)
20
0
2
4
6
8
10
12
14
16
18
Power Dissipation vs Output Current
Output Current (Amps)
14
PD-(Watts)
12
10
Vin
5.5V
8
5.0V
4.5V
6
4
2
0
0
3
6
9
12
15
18
Iout-(Amps)
Note 1: All data listed in the above graphs has been developed from actual products tested at 25°C. This data is considered typical data for the ISR.
Note 2: SOA curves represent operating conditions at which internal components are at or below manufacturer’s maximum rated operating temperatures.
Power Trends, Inc. 27715 Diehl Road, Warrenville, IL 60555 (800) 531-5782 Fax: (630) 393-6902 http://
www.powertrends.com
39
DATA SHEETS
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
PT7705❏
❏ = 1.3 to 3.5 Volts
5V5V
to Bus
3.x Converters
Products
• Single-Device: +5V input
• 5-bit Programmable:
1.3V to [email protected]
• High Efficiency
• Input Voltage Range:
4.5V to 5.5V
• Differential Remote Sense
• 27-pin SIP Package
• Parallelable with PT7749
18A “Current Boosters”
VID4=1 VID4=0
Vout
Vout
For assistance or to order, call
Application
Notes
(800) 531-5782
PT7705/7707 Series
More Application Notes
Pin-Coded Output Voltage Adjustment on the
“Big Hammer” Series ISRs
4. If active devices are used to ground the voltage control pins,
low-level open drain MOSFET devices should be used over
bipolar transistors. The inherent Vce (sat) in bipolar devices
introduces errors in the device’s internal divider network.
Discrete transistors such as the BSS138, 2N7002,
IRLML2402, or the 74C906 hex open-drain buffer are
examples of appropriate devices.
The ISRs related to Power Trends’ PT7705 incorporate pincoded voltage control to adjust the ouput voltage. The control
pins are identified VID0 - VID4 (pins 1, 2, 3, 4, & 6) respectively. When the control pins are left open-circuit, the ISR
output will regulate at its factory trimmed output voltage. Each
pin is internally connected to a precision resistor, which when
grounded changes the output voltage by a set amount. By selectively grounding VID0 -VID4, the output voltage these ISRs
can be programmed in incremental steps over the specified
output voltage range. In each case, the program code and output
voltage range offered by these ISRs are compatible with the
voltage ID specification defined by Intel Corporation for voltage
regulator modules (VRMs) used to power Pentium® microprocessors. Refer to Figure 1 below for the connection schematic,
and the respective device Data Sheet for the appropriate programming code information.
Active Voltage Programming:
Special precautions should be taken when making changes to the
voltage control progam code while the unit is powered. It is
highly recommended that the ISR be either powered down or
held in standby. Changes made to the program code while Vout
is enabled induces high current transients through the device.
This is the result of the electrolytic output capacitors being either charged or discharged to the new output voltage set-point.
The transient current can be minimized by making only incremental changes to the binary code, i.e. one LSB at a time. A
minimum of 100µs settling time between each program state is
also recommended. Making non-incremental changes to VID3
and VID4 with the output enabled is discouraged. If they are
changed, the transients induced can overstress the device resulting in a permanent drop in efficiency. If the use of active devices
prevents the program code being asserted prior to power-up,
pull pin 5 (STBY) to the device GND during the period that the
input voltage is applied to Vin. Releasing pin 5 will then allow
the device output to execute a soft-start power-up to the programmed voltage.
Notes:
1. The programming convention is as follows:Logic 0:
Logic 1:
Connect to pin12 (Remote Sense Ground).
Open circuit/open drain (See notes 2, & 4)
2. Do not connect pull-up resistors to the voltage programming pins.
3. To minimize output voltage error, always use pin 12 (Remote Sense Ground) as the logic “0” reference. While the
regular ground (pins 13-19) can also be used for programming, doing so will degrade the load reglation of the
product.
Figure 1
6 4 3 2 1
26
VID4 - VID0
+5V
7-11
1µ H
(Optional)
SNS(+)
PT7705
Vin
STBY
5
Synch
Out
27
GND
13-19
20-25
Vo
SNS(-)
12
+
Cin
+
Cout
L
O
A
D
STBY
COM
Power Trends, Inc. 27715 Diehl Road, Warrenville, IL 60555 (800) 531-5782 Fax: (630) 393-6902 http://www.powertrends.com
3
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