ST1S14 STMicroelectronics, ST1S14 Datasheet - Page 8

• Manufacturer Part Number: ST1S14
• Description: Up to 3 A step down switching regulator
• Manufacturer: STMicroelectronics

Functional description
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Functional description
The ST1S14 is based on a “peak current mode”, constant frequency control. As a
consequence the intersection between the error amplifier output and the sensed inductor
current generates the control signal to drive the power switch.
The main internal blocks shown in the block diagram in
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Figure 3.
A fully integrated sawtooth oscillator with a typical frequency of 850 kHz
A transconductance error amplifier
An high side current sense amplifier to track the inductor current
A pulse width modulator (PWM) comparator and the circuitry necessary to drive the
internal power element
The soft start circuitry to decrease the inrush current at power-up
The current limitation circuit based on the pulse by pulse current protection with
frequency divider based on FB voltage and the HICCUP protection
The bootstrap circuitry to drive the embedded N-MOS switch.
A multi input inhibit block for stand-by operation.
A circuit to implement the thermal protection function.
SOFT START
Device block diagram
REF
EA
compensation
Slope
Cp
VC
1.21V
Doc ID 17977 Rev 1
T
Rc
Cc
Comp
OSC
OTP
PG
K
R
*I
L
CONTROL
MOSFET
ShutDown
EN1
LOGIC
Reg
EN2
I_SEN
Figure 3
BOOT
Driver1
GND
Boot Reg
are:
Driver2
VIN
SW
ST1S14