L7981 STMicroelectronics, L7981 Datasheet - Page 4

• Manufacturer Part Number: L7981
• Description: Switching Converters, Regulators & Controllers 3A Step-Down Reg 3A DC 4.5-28V 250Khz
• Manufacturer: STMicroelectronics

Specifications of L7981

• Output Voltage: 0.6 V to 3 V
• Output Current: 3 A
• Input Voltage: 4.5 V to 28 V
• Switching Frequency: 250 KHz
• Operating Temperature Range: - 55 C to + 150 C
• Mounting Style: SMD/SMT
• Duty Cycle (max): 100 %
• Package / Case: QFPN-8
• Low Dropout Operation: 100% duty cycle
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Pin settings
1
1.1
1.2
4/44
Pin settings
Pin connection
Figure 2.
Pin description
Table 1.
N.
1
2
3
4
5
6
7
8
Pin connection (top view)
Pin description
SYNCH
COMP
Type
GND
OUT
F
V
EN
FB
SW
CC
Regulator output
Master/Slave synchronization. When it is left floating, a signal with a
phase shift of half a period respect to the power turn on is present at the
pin. When connected to an external signal at a frequency higher than the
internal one, then the device is synchronized by the external signal, with
zero phase shift.
Connecting together the SYNCH pin of two devices, the one with higher
frequency works as master and the other one as slave; so the two
powers turn on have a phase shift of half a period.
A logical signal (active high) enable the device. With EN higher than 1.2
V the device is ON and with EN is lower than 0.3 V the device is OFF.
Error amplifier output to be used for loop frequency compensation
Feedback input. Connecting the output voltage directly to this pin the
output voltage is regulated at 0.6 V. To have higher regulated voltages an
external resistor divider is required from Vout to FB pin.
The switching frequency can be increased connecting an external
resistor from FSW pin and ground. If this pin is left floating the device
works at its free-running frequency of 250 kHz.
Ground
Unregulated DC input voltage
SYNCH
SYNCH
SYNCH
SYNCH
COMP
COMP
COMP
COMP
Doc ID 15182 Rev 3
OUT
OUT
OUT
OUT
EN
EN
Description
GND
GND
GND
GND
FSW
FSW
FSW
FSW
FB
FB
FB
FB
V
V
V
V
CC
CC
CC
CC
L7981