Datasheet PT6921C, PT6921N, PT6922A, PT6922C, PT6922N Datasheet (Texas Instruments)

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PT6920 Series

Standard Application

5V TO 3.3V/2.5V 25 WATT DUAL OUTPUT
INTEGRATED SWITCHING REGULATOR

Ordering Information

PT6921

❏❏

❏❏

❏ = +3.3 Volts

+2.5/+1.8 Volts

PT6922

❏❏

❏❏

❏ = +3.3 Volts

+1.5 Volts

C1 = Req’d 560µF electrolytic
C2 = Req’d 330µF electrolytic
C3 = Optional 100µF electrolytic

Features

• Dual Outputs:

+3.3V/6A
+2.5V/2.2A or +1.8V/1.5A

• Adjustable Output Voltage

• Remote Sense (both outputs)

• Standby Function

• Over-Temperature Protection

• Soft-Start

• Internal Sequencing

• 23-pin SIPPackage

Pin Function

1V

1

Remote Sense

2 Do Not Connect
3 STBY
4V

in

5V

in

6V

in

7 GND
8 GND

9 GND
10 GND
11 GND
12 V

1out

Pin Function

13 V

1out

14 V

1out

15 V

1out

16 V

1

Adjust

17 Do Not Connect
18 V

2out

19 V

2out

20 V

2out

21 V

2out

22 V

2

Remote Sense

23 V

2

Adjust*

Pin-Out Information

The PT6920 is a new series of 25W
dual output ISRs designed to power the
latest generation DSP chips. Both out­put voltages are independently adjustable
with external resistors. In addition, the
second output voltage of the PT6921 can
be selected for 2.5V or 1.8V to accom­modate the next generation of DSP
chips. The internal power sequencing of
both outputs meet the latest require­ments of TI’s ‘C6000 series DSPs.

(For dimensions and PC board layout,
see Package Styles 1100 and 1110.)

PT6920

C2

+

GND

V1

OUT

V

IN

GND

4,5,6

7-11

12-15

18-21

16

C1

22

C3

+

23

1

V2

OUT

R1

R2

R3

R4

V2 Sense

V1 Sense

3

STBY

PT Series Suffix

(PT1234X)

Case/Pin
Configuration

Vertical Through-Hole

N

Horizontal Through-Hole

A

Horizontal Surface Mount

C

Preliminary Specifications

Characteristics

PT6920 SERIES

(Ta= 25°C unless noted) Symbols Conditions Min Typ Max Units

Output Current I

o

Ta = +60°C, 200 LFM, pkg N V

1

= 3.3V 0.1 — 5.5 A

V

2

= 2.5V 0 — 2.2 A

V

2

= 1.8V 0 — 1.75 A

V

2

= 1.2V 0 — 1.2 A

Ta = +25°C, natural convection V

1

= 3.3V 0 .1 — 6.0 A

V

2

= 2.5V 0 — 2.2 A

V

2

= 1.8V 0 — 1.75 A

V

2

= 1.2V 0 — 1.2 A

Input Voltage Range V

in

0.1A ≤ I

o

≤ I

max

4.5 — 5.5 V

Output Voltage Tolerance ∆V

o

V

in

= +5V, Io = I

max,

both outputs

V

o-0.1 — Vo+0.1 V

0°C ≤ Ta ≤ +65°C

Line Regulation Reg

line

4.5V ≤ V

in

≤ 5.5V, I

o

= I

max

V

1

= 3.3V — ±7 ±17 mV

V

2

= 2.5V — ±7 ±13 mV

Load Regulation Reg

load

Vin = +5V, 0.1 ≤ I

o

≤ I

max

V

1

= 3.3V — ±17 ±33 mV

V

2

= 2.5V — ±4 ±10 mV

V

o

Ripple/Noise V

n

V

in

= +5V, Io = I

max

V

1

= 3.3V — 50 — mV

V

2

= 2.5V — 25 — mV

Transient Response t

tr

Io step between 0.5xI

max

and I

max

— 25 — µSec

with C

2

= 330µF V

os

Vo over/undershoot V

1

= 3.3V — 60 — mV

V

2

= 2.5V — 60 — mV

Efficiency η V

in

= +5V, Io = 4A total — 75 — %

Switching Frequency ƒ

o

4.5V ≤ V

in

≤ 5.5V

475

600 725

kHz

0.1A ≤ I

o

≤ I

max

Absolute Maximum T

a

—

0 — +85 °C

Operating Temperature Range
Recommended Operating T

a

Forced airflow = 200 LFM

0 — +65 °C

Temperature Range Over V

in and Io

Ranges

Storage Temperature T

s

— -40 — +125 °C

Weight — Vertical/Horizontal — 29 — grams

Note:

The PT6920 series requires a 56 0µF electrolytic capacitor on the input and a 330µF electrolytic capacitor on the output for proper operation in all applications.

* This product is the subject of one or more patents. Other patents pending.

Note: for PT6921 only:

with pin 23 open, V2out=2.5V
with pin 23 shorted to pin 22, V2out=1.8V

Patent Pending*

Revised 3/9/99

Application Notes

Mechanical Outline

Product Selector Guide

For assistance or to order, call [phone]

Power Trends, Inc. 27715 Diehl Road, Warrenville, IL 60555 [phone] Fax: [phone] http://www.powertrends.com

CHARACTERISTIC DATA

PT6920 Series

Note 1:Note 1:

Note 1:Note 1:

Note 1: All data listed in the above graphs has been developed from actual products tested at 25°C. This data is considered typical data for the ISR.

PT6921, V2out = 2.5V, I2out = 2.2A (See Note 1)

Total Efficiency vs I1out

Total Power Dissipation vs I1out

Efficiency (%)PD (Watts)

I1out (A)

I1out (A)

Vin

Vin

30

40

50

60

70

80

90

0123456

Nat conv.
60LFM
200LFM

I1out (A)

Ta (°C)

Safe Operating Area vs I1out

Recommended Maximum

Operating Temperature

40

50

60

70

80

90

100

01234 56

4.5V

5.0V

5.5V

V1out Ripple vs I1out

Ripple (mV)

I1out (A)

0

2

4

6

8

10

0123456

4.5V

5.0V

5.5V

0

10

20

30

40

50

0123456

4.5V

5.0V

5.5V

Vin

For assistance or to order, call [phone]

3

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Application Notes

PT6920 Series

More Application Notes

Adjusting the Output Voltage of the PT6920 Dual
Output Voltage ISR

Both output voltages from the Power Trends PT6920 series
ISRs can be independantly adjusted higher or lower than their
factory trimmed pre-set voltage. In each case only a single
external resistor is required to adjust either V

1

(the voltage at

V

1

out, or V2 (the voltage at V2out). Table 1 gives the permis-

sible adjustment range for both V

1

and V2 for each model in the

series as V

a

(min) and V

a

(max). Note: V

2

must always be lower

than V

1

.

V1 Adjust Up: To increase the output, add a resistor R4 be­tween pin 16 (V

1

Adjust) and pins 7-11 (GND).

V

1

Adjust Down: Add a resistor (R3), between pin 16

(V

1

Adjust) and pin 1 (V1 Remote Sense).

V

2

Adjust Up: Add a resistor R2 between pin 23 (V2 Adjust)

and pins 7-11 (GND).

V

2

Adjust Down: Add a resistor (R1) between pin 23 (V2 Adjust)

and pin 22 (V

2

Remote Sense).

Refer to Figure 1 and Table 2 for both the placement and value
of the required resistor.

Notes:

1. The voltage at V

1

out and V2out may be adjusted

independantly.

2. V

2

must always be at least 0.2V lower than V1.

3. If V

1

is increased above 3.3V, the minimum input voltage to
the ISR must also be increased. The minimum required
input voltage must be (V

1

+ 1.2)V or 4.5V, whichever is

greater. Do not exceed 6.0V

4. Use only a single 1% resistor in either the (R3) or R4 loca-

Table 1

PT6920 ADJUSTMENT RANGE AND FORMULA PARAMETERS

Output Bus V1 out V2 out
Series Pt # PT6921/22 PT6921 PT6922
Adj. Resistor (R3)/R4 (R1)/R2 (R1)/R2

Vo(nom) 3.3V 2.5V 1.5
Va(min) 2.3V 1.8V 1.2
Va(max) 4.2V 3.0V 3.0
Ro (kΩ) 12.1 10.0 9.76
Rs (kΩ) 12.1 11.5 6.49

Figure 1

C1
330µF

+

C2
330µF

+

C3

100µF

+

R4

(R3) (R1)

R2

L
O
A
D

L
O
A
D

Adj Down

Adjust Up

Vin

COM COM

V2

out

V1

out

PT6920

18 - 21

237 - 11

4,5,6

Vin

V2

out

GND Vo2(adj)

V1(sns)

1

16

Vo1(adj)

12 - 15

V1

out

V2(sns)

22

STBY

3

Adjust V1

out

Adjust V2

out

tion to adjust V1, and in the (R1) or R2 location to adjust V2.
Place the resistor as close to the ISR as possible.

5. Never connect capacitors to either the V

1

Adjust or

V

2

Adjust pins. Any capacitance added to these control pins

will affect the stability of the respective regulated output.

6. To comply with the ISRs power dissipation limits, changes
made to either output voltage (V

1

or V2) may affect the
maximum current available from both outputs. For more
information, consult the related applications note, “Deter­mining the Maximum Output Current for the PT6920
Series Dual Output ISR.”

The adjust up and adjust down resistor values can also be calcu­lated using the following formulae. Be sure to select the correct
formula parameter from Table 1 for the output and model being
adjusted.

(R1)/(R3) =

R

o

(Va – 1)

– R

s

kΩ

V

o

– V

a

R2/R4 =

R

o

– R

s

kΩ

V

a

– V

o

Where: Vo= Original output voltage, (V1 or V2)

V

a

= Adjusted output voltage

R

o

= The resistance value from Table 1

R

s

= The series resistance from Table 1

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Application

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Notes

PT6920 Series

Table 2

PT6920 ADJUSTMENT RESISTOR VALUES

Output Bus V1 out V2 out
Series Pt # PT6921/22 PT6921 PT6922
Adj Resistor (R3)/R4 (R1)/R2 (R1)/R2
Vo(nom) 3.3Vdc 2.5Vdc 1.5Vdc

Va(req’d)

1.2 (0.0)kΩ

1.25 (3.3)kΩ

1.3 (8.2)kΩ

1.35 (16.3)kΩ

1.4 (32.6)kΩ

1.45 (81.4)kΩ

1.5

1.55 189.0kΩ

1.6 91.1kΩ

1.65 58.6kΩ

1.7 42.3kΩ

1.75 32.6kΩ

1.8 (0.0)kΩ 26.0kΩ

1.85 (1.6)kΩ 21.4kΩ

1.9 (3.5)kΩ 17.9kΩ

1.95 (5.8)kΩ 15.2kΩ

2.0 (8.5)kΩ 13.0kΩ

2.05 (11.8)kΩ 11.3kΩ

2.1 (16.0)kΩ 9.8kΩ

2.15 (21.4)kΩ 8.5kΩ

2.2 (28.5)kΩ 7.5kΩ

2.25 (38.5)kΩ 6.5kΩ

2.3 (3.6)kΩ (53.5)kΩ 5.7kΩ

2.35 (5.1)kΩ (78.5)kΩ 5.0kΩ

2.4 (6.7)kΩ (129.0)kΩ 4.4kΩ

2.45 (8.5)kΩ (279.0)kΩ 3.8kΩ

2.5 (10.6)kΩ 3.3kΩ

2.55 (12.9)kΩ 189.0kΩ 2.8kΩ

2.6 (15.6)kΩ 88.5kΩ 2.4kΩ

2.65 (18.6)kΩ 55.2kΩ 2.0kΩ

2.7 (22.2)kΩ 38.5kΩ 1.6kΩ

2.75 (26.4)kΩ 28.5kΩ 1.3kΩ

2.8 (31.5)kΩ 21.8kΩ 1.0kΩ

2.85 (37.6)kΩ 17.1kΩ 0.7kΩ

2.9 (45.4)kΩ 13.5kΩ 0.5kΩ

2.95 (55.3)kΩ 10.7kΩ 0.2kΩ

3.0 (68.6)kΩ 8.5kΩ 0.0kΩ

3.05 (87.1)kΩ

3.1 (115.0)kΩ

3.15 (161.0)kΩ

3.2 (254.0)kΩ

3.25 (532.0)kΩ

3.3

3.4 109.0kΩ

3.5 48.4kΩ

3.6 28.2kΩ

3.7 18.2kΩ

3.8 12.1kΩ

3.9 8.1kΩ

4.0 5.2kΩ

4.1 3.0kΩ

4.2 1.3kΩ

R1/R3 = (Red) R2/R4 = Black

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