RICHTEK RT9171-25CL, RT9171-25CM, RT9171-33CL, RT9171-33CM Datasheet

RT9171

DS9171-02 May 2001 www.richtek-ic.com.tw

1

2A Fixed and Adjustable Low Dropout

Positive Voltage Regulators

General Description

The RT9171 is a high performance positive voltage

regulator designed for applications requiring low

dropout at fully rated current. Additionally, the

RT9171 provides excellent regulation over variations

in line and load. Outstanding features include low

dropout performance at rated current, fast transient

response, internal current-limiting, and thermal-

shutdown protection of the output device. The

RT9171 three-terminal regulator offers fixed 2.5V

and 3.3V output voltages, and adjustable voltage

options available in TO-252 and TO-263 packages.

Applications

z

Active SCSI Termination

z

Low Voltage Microcontrollers

z

Switching Power Supply Post-Regulator

Ordering Information

RT9171-

 

Features

z

Low Dropout, 1.6V Max.

z

Full Current Rating Over Line and Temperature

z

Fast Transient Response

z ±

±±

±1 %%%% Output Voltage Accuracy

z

Adjustable and Fixed Output Voltage

z

TO- 252 and TO- 263 Packages

Pin Configurations

Part Number Pin Configurations

RT9171-CL

(Plastic TO-252)

TOP VIEW

1. ADJ/GND

2. VOUT (TAB)

3. VIN

RT9171-CM

(Plastic TO-263)

TOP VIEW

1. ADJ/GND

2. VOUT (TAB)

3. VIN

Typical Application Circuit

Operating temperature range

C: Commercial standard

Package type
L : TO-252
M : TO-263

Output voltage

Default : Adjustable

25 : 2.5V output voltage

33 : 3.3V output voltage

123

1

2

3

RT9171

ADJ

VOUT

V

REF

R1
120
1%

R2
195
1%

V

OUT

= 3.3V

I

ADJ

V

IN

= 5V

+

C2
22µF

TANT

+

C1

10µFF

Adj ustable Volt ag e Regul ator

(1) C1 needed if device is far from filter capacitors.
(2) C2 required for stability.

V

OUT

= V

REF

(1+ ) + I

ADJ R2

R1

R2

VIN

RT9171

www.richtek-ic.com.tw DS9171-02 May 2001

2

Pin Description

Pin Name Pin Function

ADJ / GND Adjust Output or Ground

VOUT Output Voltage

VIN Power Input

Absolute Maximum Ratings

z Input Voltage 9V

z Operating Junction Temperature Range −40°C to 125°C

z Storage Temperature Range −65°C to 150°C

z Lead Temperature (Soldering, 10 sec.) 260°C

z Package Thermal Resistance

TO-252, θ

JC

15°C/W

TO-252, θ

JA

56°C/W

TO-263, θ

JC

8°C/W

TO-263, θ

JA

19.4°C/W

Electrical Characteristics

(TA = 25°C, unless otherwise specified)

Parameter Symbol Test Conditions Min Typ Max Units

I

OUT

= 10mA, (V

IN

- V

OUT

) = 2V

T

A

= 25°C

1.238 1.250 1.262

Reference Voltage

(1)

RT9171

V

REF

10mA < I

OUT

< 2A,

1.6V < V

IN

- V

OUT

< 9V

1.225 1.250 1.270

V

RT9171-25

2.475 2.5 2.525

Output Voltage

RT9171-33

V

OUT

VIN = V

OUT

+2V, I

OUT

= 10mA

3.267 3.3 3.333

V

Line Regulation

(1)

∆V

LINE

I

OUT

= 10mA

1.6V ≤ V

IN

- V

OUT

to VIN = 9V

-- 0.1 0.3 %

Load Regulation

(1)

∆V

LOAD

(V

IN

− V

OUT

) = 2V, 0mA ≤ I

OUT

≤ 2A -- 0.2 0.4 %

I

OUT

= 100mA -- 1.1 1.2

Dropout Voltage

(2)

V

DROP

I

OUT

= 2A -- 1.4 1.6

V

Current Limit

I

LIMIT

V

IN

= 5V

2.2 3 -- A

Minimum Load Current RT9171

(V

IN

- V

OUT

) = 2V -- 5 10 mA

Ripple Rejection PSRR

f

RIPPLE

= 120H

Z

, (VIN - V

OUT

) = 2V,

V

RIPPLE

= 1V

P-P

-- 72 -- dB

Adjust Pin Current

I

ADJ

-- 65 120 µA

Adjust Pin Current Change

∆I

ADJ

10mA ≤ I

OUT

≤ 1A, V

IN

= 5V -- 0.2 5 µA

Notes: (1) Low duty cycle pulse testing with Kelvin connections.

(2) ΔV

OUT

and

ΔV

REF

= 1%.