UCD7201_15 Datasheet, PDF (16/30 Pages) Texas Instruments – UCD7201 Digital Control Compatible Dual Low-Side ±4 Amp MOSFET Drivers with Programmable Common Current Sense

UCD7201
SLUS645F – FEBRUARY 2005 – REVISED DECEMBER 2014
Typical Applications (continued)
VIN
Bias Supply
UCC28089
1 SYNC
VDD 16
2 DIS
3 CT
GND 13
OUTA 15
4 CS
OUTB 14
UCD7201
1 NC
NC 14
2 3V3
PVDD 12
VDD 13
4 AGND
3 IN1
OUT1 11
5 IN2
OUT2 10
6 CLF PGND 9
7 ILIM
CS 8
Bias Winding
www.ti.com
VOUT
Figure 27. Intermediate Bus Converter
9.2.2.1 Design Requirements
In this design example, the input current is sensed by a current shunt, the cycle-by-cycle protection threshold is
set at 5 A.
9.2.2.2 Detailed Design Procedure
I_peak × R_sense = V_ILIM – 0.025
(6)
Rsense
=
VILIM - 0.025
Ipeak
(7)
The current limit threshold can be set to any value between 0.25 V and 1.0 V, so R_sense need to be between
0.045 Ω and 0.195 Ω. Let’s choose R_sense as 0.15 Ω. VILIM need to be 0.775 V in order to protect input current
at 5 A.
Since the controller is analog, it cannot program the V_ILIM, however, V_ILIM can be implemented by a voltage
divider connect the pin 2 of UCD7201. Since the voltage on pin 2 is 3.3 V, so the voltage divider needs to be:
Rbottom _{´ 3.3 = 0.775}
Rbottom + Rtop
(8)
9.2.3 Application Curves
See Figure 26.
16
Submit Documentation Feedback
Product Folder Links: UCD7201
Copyright © 2005–2014, Texas Instruments Incorporated