TLF50281EL Infineon Technologies, TLF50281EL Datasheet - Page 29

• Manufacturer Part Number: TLF50281EL
• Manufacturer: Infineon Technologies

Specifications of TLF50281EL

• Packages: PG-SSOP-14
• Comment: Asyncronous low-Iq-Buck; 5V/500mA; Iq
• Vq (max): 5V
• Iq (max): 500.0 mA
• Iq (typ): 45.0 µA
• Output: Buck Converter

8
8.1
The oscillator supplies the device with a constant frequency. The power switch will be switched on and off with a
constant frequency
synchronized to this frequency.
The oscillator frequency can be set by connecting an external resistor
the following table (selected values, for more precise setting please refer to
Frequency Setting Resistor
8.1.1
8.1.2
Figure 13
The turn-on frequency can optionally be set externally via the SYNC pin. In this case the synchronization of the
PWM-on signal refers to the falling edge of the SYNC-pin input signal. In case the synchronization to an external
clock signal is not needed, the SYNC pin should be connected to ground. The frequency setting resistor
also necessary for SYNC option and must be dimensioned according to the desired synchronization frequency
(the ratio between synchronization and internal frequency has to be less than or equal to 1).
The synchronization function is not available in PFM mode.
Data Sheet
3,2
3,0
2,8
2,6
2,4
2,2
2,0
1,8
1,6
1,4
1,2
1,0
0,8
Frequency adjusting resistor
Oscillator frequency
25
Oscillator
Description
Switching Frequency
35
f
OSC
. The time period
45
55
f
OSC
versus Frequency setting Resistor
65
T
PWM
R
f
osc
FREQ
is derived from this frequency and some safety functions are
Resistor at FREQ pin [kΩ]
75
29
39
2600
85
95
47
2200
R
105
FREQ
56
1950
Figure 13
between pin FREQ and GND using
R
115
FREQ
82
1400
.
below).
125
Rev. 1.0, 2011-10-24
100
1200
135
TLF50281EL
kΩ
kHz
145
Oscillator
R
FREQ
is