Datasheet

TSM101/A
11/13
The current control is given by the choice of the
voltage drop through the sense resistor R5 (to be
linked to the nominal current of the application)
and by the value of the sense resistor itself.
For medium currents (< 1A), a good value for the
voltage drop through R5 can be Vsense = 200mV
(dissipation < 200mW).
The resistor bridge R2/R3 should be chosen fol-
lowing equation 2 :
• Vsense = R3/(R2+R3)xVref eq2
The total value of the resistor bridge should be in
the range of the kW in order to ensure a proper
charge for the voltage reference (in the range of
the mA).
To set the current limit, the sense resistor R5
should be chosen following equation 3 :
• Ilim = Vsense/R5 eq3
The internal current generator (Isce) can be used
to offset the current limitation with a lower value.
This current generator is activated by connecting
pin 2 to ground. It is inhibited if pin 2 is connected
to the positive rail via the pull up resistor R1.
The current offset is given by the choice of the re-
sistor R4.
If Ilim1 is the current limit calculated in the previ-
ous paragraph, and Ilim2 is the current limit that is
to be set when pin 2 is connected to ground, R4
should be chosen following equation 4 :
• R4 = (Vsense - Ilim2xR5)/Isce eq4
where Isce = 1.4mA
C4 and C5 are bypass capacitors used to smooth-
en the regulated outputs.
C2 and C3 are capacitors used for high frequency
compensation.
EXAMPLES OF COMPONENT LISTS
Table 1 summerizes a few examples of compo-
nent lists to generate quickly 15V/700mA/200mA,
12V/1A/500mA or 8.2V/200mA/100mA voltage
and current regulations.
Figure 2
Voltage/
Current
Control
15V
700mA
200mA
12V
1A
500mA
8.2V
200mA
100mA
R1 10k
Ω
10k
Ω
10k
Ω
R2 1.2k
Ω
1.2k
Ω
1.2k
Ω
R3 220k
Ω
220k
Ω
220k
Ω
R4 100
Ω
68
Ω
68
Ω
R5 1.2
Ω
x 4 0.8
Ω
x 4 1
Ω
x 1
R6 1k
Ω
1k
Ω
1k
Ω
R7 12k
Ω
8.2k
Ω
5.6k
Ω
P1 100
Ω
100
Ω
100
Ω
2 straps 0
Ω
0
Ω
0
Ω
C2 100nF 100nF 100nF
C3 100nF 100nF 100nF
C4 10
µ
F22
µ
F4.7
µ
F
C5 100nF 100nF 100nF