RT7257C 데이터 시트보기 (PDF) - Richtek Technology
부품명
상세내역
제조사
RT7257C Datasheet PDF : 14 Pages
| |||
RT7257C
Typical Application Circuit
VIN
4.5V to 18V
Chip Enable
CIN
10µF x 2
2 VIN
BOOT 1
RT7257C
SW 3
7 EN
CBOOT L
0.1µF 10µH
R1
75k
8 SS
FB 5
CSS
0.1µF
4, 9 (Exposed Pad)
GND
COMP 6
CC
4.7nF
RC
12k
R2
24k
VOUT
3.3V
COUT
22µF x 2
CP
Open
VOUT (V)
8
5
3.3
2.5
1.5
1.2
1
Table 1. Suggested Components Selection
R1 (kΩ)
27
62
75
R2 (kΩ)
3
11.8
24
RC (kΩ)
24
18
12
CC (nF)
4.7
4.7
4.7
L (μH)
22
15
10
25.5
12
10.5
12
12
24
3
12
8.2
4.7
6.8
3.6
4.7
3.6
3
4.7
3.6
2.7
4.7
3.6
COUT (μF)
22 x 2
22 x 2
22 x 2
22 x 2
22 x 2
22 x 2
22 x 2
Functional Pin Description
Pin No.
1
2
Pin Name
BOOT
VIN
Pin Function
Bootstrap for High Side Gate Driver. Connect a 0.1μF or greater ceramic
capacitor from BOOT to SW pins.
Input Supply Voltage, 4.5V to 18V. Must bypass with a suitable large ceramic
capacitor.
3
SW
Switch Node. Connect this pin to an external L-C filter.
4,
9 (Exposed Pad)
GND
Ground. The exposed pad must be soldered to a large PCB and connected to
GND for maximum power dissipation.
5
FB
Feedback Input. It is used to regulate the output of the converter to a set value
via an external resistive voltage divider.
Compensation Node. COMP is used to compensate the regulation control
6
COMP
loop. Connect a series RC network from COMP to GND. In some cases, an
additional capacitor from COMP to GND is required.
Enable Input. A logic high enables the converter; a logic low forces the
7
EN
RT7257C into shutdown mode reducing the supply current to less than 3μA.
Attach this pin to VIN with a 100kΩ pull up resistor for automatic startup.
Soft-Start Control Input. SS controls the soft-start period. Connect a capacitor
8
SS
from SS to GND to set the soft-start period. A 0.1μF capacitor sets the
soft-start period to 13.5ms.
Copyright ©2012 Richtek Technology Corporation. All rights reserved.
www.richtek.com
2
is a registered trademark of Richtek Technology Corporation.
DS7257C-02 September 2012
Share Link: 