EVAL6730 STMicroelectronics, EVAL6730 Datasheet - Page 9

• Manufacturer Part Number: EVAL6730
• Description: EVAL BOARD FOR L6730XX
• Manufacturer: STMicroelectronics
• Type: Motor / Motion Controllers & Driversr

Specifications of EVAL6730

• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Non-Isolated
• Power - Output: 66W
• Voltage - Output: 3.3V
• Current - Output: 20A
• Voltage - Input: 4.5 ~ 14V
• Regulator Topology: Buck
• Frequency - Switching: 400kHz
• Board Type: Fully Populated
• Utilized Ic / Part: L6730
• Input Voltage: 8 V to 52 V
• Product: Power Management Modules
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: L6208
• Other names: 497-5501

2.6 Charge pump external components
An internal oscillator, with its output at CP pin, switches from GND to 10V with a typical frequency of 600kHz
(see Figure 7).
Figure 7. Charge Pump.
When the oscillator output is at ground, C
biased and the charge flows from C
imum voltage of V
With a differential voltage between V
ical current drawn by the V
Resistor R4 is added to reduce the maximum current in the external components and to reduce the slew rate of
the rising and falling edges of the voltage at the CP pin, in order to minimize interferences with the rest of the
circuit. For the same reason care must be taken in realizing the PCB layout of R4 , C5 , D1 , D2 connections (see
also the Layout Considerations section). Recommended values for the charge pump circuitry are:
D1, D2 : 1N4148
R4
C5
C8
Due to the high charge pump frequency, fast diodes are required. Connecting the cold side of the bulk capacitor
(C8) to V
R4 = 100
10 V in all conditions. 1N4148 diodes withstand about 200 mA DC (1 A peak), and the maximum reverse voltage
is 75 V, so they should fit for the majority of applications.
S
: 100
: 10nF 100V ceramic
: 220nF 25V ceramic
instead of GND the average current in the external diodes during operation is less than 10 mA (with
); at startup (when V
S
(1/8 W)
+ 10V - V
V
S
+ 10 V - V
10 V
BOOT
f = 600 kHz
D1
D 1
S
- V
- V
V
pin is 1.85 mA.
B O OT
is provided to the IC) is less than 200 mA while the reverse voltage is about
T o H igh -Side
G ate D r ivers
D 2
D2
5
S
to C
, which supplies the high-side gate drivers.
and V
D 1
8
C 5
R 4
5
CP
through D
BOOT
is charged by V
of about 9V and both the bridges switching at 50kHz, the typ-
10 V
D 2
R
R
1
V
DS (ON )
D S(O N )
, so the V
SA
f = 600 kH z
= 70
= 70
V
S B
S
through D
C8
BOOT
V
V
C h arge Pu mp
S
S
+ 10 V - V
O scillator
pin, after a few cycles, reaches the max-
- V
10 V
D 1
2
AN1451 APPLICATION NOTE
. When it rises to 10V, D
L 6208
5 V
D 1
2
is reverse
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