L6722TR STMicroelectronics, L6722TR Datasheet - Page 26

• Manufacturer Part Number: L6722TR
• Description: IC BUCK ADJ 2A TRPL 36VFQFPN
• Manufacturer: STMicroelectronics
• Type: Step-Down (Buck)r

Specifications of L6722TR

• Internal Switch(s): No
• Synchronous Rectifier: No
• Number Of Outputs: 3
• Voltage - Output: Adj to 0.8V
• Current - Output: 2A
• Frequency - Switching: 100kHz
• Voltage - Input: 12V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 36-VFQFN, 36-VFQFPN
• Power - Output: 3.5W
• Operating Temperature Range: - 40 C to + 125 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-5904-2

10 Oscillator
10
Caution:
26/34
Oscillator
The internal oscillator generates the triangular waveform for the PWM charging and
discharging with a constant current an internal capacitor. The switching frequency for each
channel, F
side results in being tripled (300kHz).
The current delivered to the oscillator is typically 25µA (corresponding to the free running
frequency F
between the OSC pin and SGND. Since the OSC pin is fixed at 1.24V, the frequency is varied
proportionally to the current sunk from the pin considering the internal gain of 4KHz/µA.
In particular connecting R
relationship:
Maximum programmable switching frequency per phase must be limited to 500kHz to avoid
current reading errors causing, as a consequence, current sharing errors. Anyway, device
power dissipation must be checked prior to design high switching frequency systems.
Figure 15. R
R
OSC
SW
SW
, is internally fixed at 100kHz so that the resulting switching frequency at the load
vs. SGND
OSC
=100kHz) and it may be varied using an external resistor (R
250
200
150
100
50
vs. Switching frequency
0
100
F
OSC
150
SW
=
to SGND the frequency is increased according to the following
200
100kHz
250
Fsw [kHz] Programmed
+
--------------------------- -
R
300
1.240V
OSC
(
kΩ
350
)
⋅
4
400
kHz
---------- -
µA
450
=
100kHz
500
+
OSC
550
4.96
--------------------------- -
R
OSC
) connected
⋅
(
kΩ
10
6
)
L6722