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Part: PT7756N
Category:
Power Management
-> Plug-in Power Solutions->Non-Isolated->Single Posi
Description: ti PT7756, 6.6 to 12.8Vout 15Amp 24V-Input 'Big-Hammer III' Programmable Isr
Company: Texas Instruments, Inc.
Datasheet: Download PT7756N datasheet File size : 117 kB
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Datasheet text preview:
PT7750 Series
15 Amp 24V Input "Big Hammer III" Programmable ISR
SLTS053A
(Revised 6/30/2000)
The PT7750 series is a +24V input, 15 Amp output, highperformance Integrated Switching Regulator (ISR) housed in a 27-pin SIP package. The 15A capability allows easy integration of the latest high-speed, low-voltage µPs and bus drivers into +24V distributed power systems. The PT7750 series has been designed to work in parallel with one or
more of the PT7747 current boosters for increased Iout in increments of 15A. The output voltage of the PT7750 series can be easily programmed over a wide range with a 5-bit input. A differential remote sense is provided which automatically compensates for any voltage drop from the ISR to the load. 2000µF of output capacitance is required for proper operation.
Pin-Out Information
Pin Function Pin Function
14 15 16 17 18 19 20 21 22 23 24 25 26 27 GND GND GND GND GND GND Vout Vout Vout Vout Vout Vout
Remote Sense Vout
Features
· +24V bus input · High Efficiency · Differential Remote Sense · 27-pin SIP Package · Parallelable with PT7747 15A current boosters
Standard Application
PROGRAMMING PINS
VID0 VID1 VID2 VID3 VID4 REMOTE SENSE (+)
64321 26
VIN
L1
7 - 11
1µH +
27
PT7750
13 - 19 5 12
20 - 25
VOUT
CIN SYNC OUT GND STBY*
COUT
+
LOAD
GND
REMOTE SENSE (-)
C in = Required 560µF electrolytic (See input filter note) Cout = Required 2000µF electrolytic L1 = Optional 1µH input choke
1 2 3 4 5 6 7 8 9 10 11 12 13
VID0 VID1 VID2 VID3 STBY* - Stand-by VID4
Vi n Vi n Vi n Vi n Vi n
Remote Sense Gnd
GND
For STBY* pin: open = output enabled ground = output disabled.
Sync Out
Specifications
Characteristics (Ta = 25°C unless noted) Output Current Input Voltage Range Undervoltage Lockout Threshold Output Voltage T lerance o Line Regulation Load Regulation Vo Ripple/Noise Transient Response with Cout = 2000µF Efficiency
PT7750 SERIES
Symbols Io Vi n V uvl V o R e gl i n e Regload Vn tt r V os Conditions Ta = +60°C, 200 LFM Ta = +25°C, natural convection 0.1A I o I o max 0.1A I o I o max Vin = +24V, Io = 15A PT7751 0°C Ta +55°C PT7756 20V Vin 28V, Io = Io max (w/remote sense) Vin = +24V, 0.1 Io Io max (w/remote sense) Vin = +24V, Io = Io max Io step between 7.5A and 15A Vo over/undershoot Vin = +24V, Io = 10A 20V V in 28V 0.1A I o 15A -- -- Ver tical/Horizontal Vo = 5.0V Vo = 3.3V Vo = 2.5V Min 0. 1 0. 1 -- -- -- -- -- -- -- -- -- -- -- 300 0 -40 --
(1) (1)
Typ -- -- -- 18.7 -- -- ±15 ±10 75 100 200 88 84 80 350 -- -- 53/66
Max 15 (2) 15 (2) 28.0 -- ±80 ±160 -- -- -- -- -- -- -- -- 400 +85
(3)
Units A V V mV mV mV mV µSec mV % kHz °C °C grams
20.0
Switching Frequency Absolute Maximum Operating T mperatur e Range e Storage T mperatur e e Weight
o Ta Ts --
+125 --
Notes (1) ISR-will operate down to no load with reduced specifications. Please note that this product is not short-circuit protected. (2) The PT7750 series can be easily paralleled with one or more of the PT7747 Current Boosters to provide increased output current in increments of 15A (3) See safe operating area curves or contact the factory to determine the appropriate derating.
Output Capacitors: The PT7750 series requires a minimum output capacitance of 2000µF for proper operation. Do not use Oscon type capacitors. The maximum allowable output capacitance is (42,000 ÷ Vout)µF for the PT7751, (96,000 ÷Vout)µF for the PT7756, or 15,000µF, whichever is less. Input Filter: An input inductor is optional for most applications. The input inductor must be sized to handle 9ADC with a typical value of 1µH. The input capacitance must be rated for a minimum of 8.0 Arms of ripple current when operated at maximum output current and maximum output voltage. Contact an applications engineer for input capacitor selection for applications at other output voltages and output currents.
For technical support and more information, see inside back cover or visit www.ti.com/powertrends
PT7750 Series
15 Amp 24V Input "Big Hammer III" Programmable ISR
Programming Information
PT7751
1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 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 2.5V 2.6V 2.7V 2.8V 2.9V 3.0V 3.1V 3.2V 3.3V 3.4V 3.5V 3.6V 3.7V 3.8V 3.9V 4.0V 4.1V 4.2V 4.3V 4.4V 4.5V 4.6V 4.7V 4.8V 4.9V 5.0V 5.1V 5.2V 5.3V 5.4V 5.5V 5.6V
Ordering Information
PT7756
6.6V 6.8V 7.0V 7.2V 7.4V 7.6V 7.8V 8.0V 8.2V 8.4V 8.6V 8.8V 9.0V 9.2V 9.4V 9.6V 9.8V 10.0V 10.2V 10.4V 10.6V 10.8V 11.0V 11.2V 11.4V 11.6V 11.8V 12.0V 12.2V 12.4V 12.6V 12.8V
VID4=1 VID4=0 VID4=1 VID4=0 VID3 VID2 VID1 VID0 Vout Vout Vout Vout
PT7751J = 2.5 to 5.6 Volts PT7756J = 6.6 to 12.8 Volts
(For dimensions and PC board layout, see Package Styles 1000 and 1010.)
PT Series Suffix (PT1234X)
Case/Pin Configuration Vertical Through-Hole N Horizontal Through-Hole A Horizontal Surface Mount 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.
TYPICAL
CHARACTERISTICS
PT7751 Safe Operating Area (@Vin=+24V, Over Vo Range)
90
Efficiency vs Output Current (@Vin=+24V)
10 0 90
Ambient Temperature (°C)
80 70 60 50 40 30 20
Efficiency (%)
80 70 60 50 40 0 3 6 9 12 15
Vout
12. 0V 5.0V 3.3V 2.5V
Airflow
Nat conv 60L FM 120 LFM 200 LFM
0
3
6
9
12
15
Output Current (A)
Output Current (A)
Ouput Ripple vs Output Current (@Vin=+24V)
70
90
PT7756 Safe Operating Area (@Vin=+24V, Over Vo Range)
50
Ambient Temperature (°C)
60
80 70 60 50 40 30 20
Vout
12. 0V 5.0V 3.3V 2.5V
Riplle (mV)
Airflow
Nat conv 60 LF M 12 0L FM 20 0L FM
40 30 20 10 0 0 3 6 9 12 15
0
3
6
9
12
15
Output Current (A)
Output Current (A)
Power Dissipation vs Output Current (@Vin=+24V)
16 14 12
Pd (Watts)
Vout
12. 0V 5.0V 3.3V 2.5V
10 8 6 4 2 0 0 3 6 9 12 15
Output Current (A)
Note: 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
PT7750 Series
Pin-Coded Output Voltage Adjustment on the "Big Hammer III" Series ISRs
Power Trends PT7750 series ISRs incorporating pincoded voltage control, use pins 1, 2, 3, 4, & 6 to adjust the ouput voltage. The control pins are identified VID0 - VID4 respectively. When the control pins are left open-circuit, the ISR output will regulate at its factory trimmed output voltage. Each control pin is internally connected to a precision resistor, and when grounded increases the output voltage by a set amount. The internal resistors are binary code weighted, allowing the output voltage of the ISR to be programmed as a function of a binary code. VID0 represents the LSB, and VID4 the MSB (or range change bit). The output voltage ranges offered by these regulators are compatible with some microprocessors, and provide a convenient method of output voltage selection for many other applications. Refer to Figure 1 below for the connection schematic, and the PT7750 Data Sheet for the programming code information. Notes: 1. The programming convention is as follows:Logic 0: Connect to pin12 (Remote Sense Ground). Logic 1: Open circuit/open drain (See notes 2, & 4) 2. Do not connect pull-up resistors to the voltage programming pins. 3. T minimize output voltage error, always use pin 12 o (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. 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. 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 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. For more information on the use of the Standby function, consult the related application note, "Using the Standby Function on the `Big Hammer III' Programmable ISR Series."
Figure 1
6
4321 V I D 4 - VID0
26 SNS(+) 20-25
+24V
7-11
1µH (Optional)
Vin
PT7750
Synch Out 27 GND 13-19 5 12
Vo
STBY
SNS(-)
+
+
Cin
Cout
L O A D
STBY
COM
For technical support and more information, see inside back cover or visit www.ti.com/powertrends
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