L7980ATR datasheet(12/44 Pages) STMICROELECTRONICS

Part #	L7980ATR

Description	2 A step-down switching regulator

PDF	44 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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12 / 44 page

Functional description

L7980

12/44

Doc ID 15181 Rev 4

In continuos conduction mode (CCM), the transfer function of the power section has two

poles due to the LC filter and one zero due to the ESR of the output capacitor. Different

kinds of compensation networks can be used depending on the ESR value of the output

capacitor. In case the zero introduced by the output capacitor helps to compensate the

double pole of the LC filter a type II compensation network can be used. Otherwise, a type

III compensation network has to be used (see Chapter 6.4 for details about the

compensation network selection).

Anyway the methodology to compensate the loop is to introduce zeros to obtain a safe

phase margin.

Table 5.

Uncompensated error amplifier characteristics

Low frequency gain

100dB

GBWP

4.5MHz

Slew rate

7V/

μs

Output voltage swing

0 to 3.3V

Maximum source/sink current

17mA/25mA

L7980ATR Datasheet(PDF) 12 Page - STMicroelectronics