L5981 STMicroelectronics, L5981 Datasheet - Page 3

• Manufacturer Part Number: L5981
• Description: IC REG SW STEP DOWN 1A 8-VFQFPN
• Manufacturer: STMicroelectronics
• Type: Step-Down (Buck)r

Specifications of L5981

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 0.6 ~ 18 V
• Current - Output: 1A
• Frequency - Switching: 250kHz ~ 1MHz
• Voltage - Input: 2.9 ~ 18 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-VFQFN, 8-VFQFPN
• Power - Output: 1.5W
• Output Voltage: 3 V
• Output Current: 1 A
• Input Voltage: 2.9 V to 18 V
• Switching Frequency: 220 KHz to 275 KHz
• Operating Temperature Range: - 40 C to + 150 C
• Mounting Style: SMD/SMT
• Duty Cycle (max): 100 %
• Low Dropout Operation: 100 % duty cycle
• For Use With: 497-6385 - BOARD EVAL FOR L5981
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

L5981
1
1.1
1.2
Pin settings
Pin connection
Figure 2.
Pin description
Table 1.
Pin n°
1
2
3
4
5
6
7
8
Pin connection (top view)
Pin description
SYNCH
COMP
Type
GND
OUT
F
V
INH
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) disable the device. With INH higher than
1.9 V the device is OFF and with INH lower than 0.6 V the device is ON.
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
COMP
COMP
OUT
OUT
Doc ID 13004 Rev 6
INH
INH
Description
FB
FB
GND
GND
FSW
FSW
V
V
CC
CC
Pin settings
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