Document
ST1S14
Up to 3 A step-down switching regulator
Datasheet - production data
HS+O6P283- exHp[SoRsVeHdGSpDaGd
Applications
• Factory automation • Printers • DC-DC modules • High current LED drivers
Features
• 3 A DC output current • Operating input voltage from 5.5 V to 48 V • 850 kHz internally fixed switching frequency • Internal soft-start • Power good open collector output • Current mode architecture • Embedded compensation network • Zero load current operation • Internal current limiting • Inhibit for zero current consumption • 2 mA maximum quiescent current over
temperature range • 250 mΩ typ. RDS(on) • Thermal shutdown
Description
The ST1S14 is a step-down monolithic power switching regulator able to deliver up to 3 A DC current to the load depending on the application conditions. The high current level is also achieved thanks to a HSOP8 package with exposed frame, that allows to reduce the Rth(JA) down to approximately 40 °C/W. The output voltage can be set from 1.22 V. The device uses an internal Nchannel DMOS transistor (with a typical RDS(on) of 200 mΩ) as the switching element to minimize the size of the external components. The internal oscillator fixes the switching frequency at 850 kHz. Power good open collector output validates the regulated output voltage as soon as it reaches the regulation. Pulse-by-pulse current limit offers an effective constant current short-circuit protection. Current foldback decreases overstress in a persistent short-circuit condition.
Figure 1. Application schematic
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December 2020
This is information on a product in full production.
DocID17977 Rev 3
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www.st.com
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Contents
Contents
ST1S14
1
Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.1 Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.3 Enable inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2
Electrical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.3 ESD protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4
Function description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.1 Power supply and voltage reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
4.2 Voltage monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
4.3 Soft-start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
4.4 Error amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.5 Inhibit function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.6 Thermal shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5
Additional features and limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.1 Maximum duty cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.2 Minimum output voltage over VIN range . . . . . . . . . . . . . . . . . . . . . . . . . . 15
6
Closing the loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
6.1 GCO(s) control to output transfer function . . . . . . . . . . . . . . . . . . . . . . . . 17 6.2 Error amplifier compensation network . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6.3 Voltage divider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
6.4 Total loop gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
7
Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
7.1 Component selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
7.1.1 Input capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
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ST1S14
Contents
7.1.2 Output capacitor . . . . . . . . . . . . . . . . . . ..