Richtek RT7277GSP Schematic [ru]

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RT7277

3A, 18V, 700kHz ACOTTM Synchronous Step-Down Converter

General Description

The RT7277 is a synchronous step-down DC/DC converter

with Advanced Constant On-Time (ACOT

) mode control.

It achieves high power density to deliver up to 3A output

current from a 4.5V to 18V input supply. The proprietary

ACOTTM mode offers an optimal transient response over a

wide range of loads and all kinds of ceramic capacitors,

which allows the device to adopt very low ESR output

capacitors for ensuring performance stabilization. In

addition, RT7277 keeps an excellent constant switching

frequency under line and load variation and the integrated

synchronous power switches with the ACOTTM mode

operation provides high efficiency in whole output current

load range. Cycle-by-cycle current limit provides an

accurate protection by a valley detection of low side

MOSFET and external soft-start setting eliminates input

current surge during startup. Protection functions also

include output under voltage protection, output over voltage

protection, and thermal shutdown.

Marking Information

RT7277GSP : Product Number

RT7277 GSPYMDNN

YMDNN : Date Code

Features

ACOTTM Mode Enable s Fa st T ra n sient Respon se

z 4.5V to 18V Input Voltage Range

z 3A Output Current

ΩΩ

z 60m

Ω Internal Low Site N-MOSFET

ΩΩ

z Advanced Constant On-Time Control

z Support All Ceramic Capa citors

z Up to 95% Efficiency

z 700kHz Switching Frequency

z Adjustable Output Voltage from 0.765V to 8V

z Adjustable Soft-Start

z Cycle-by-Cycle Current Limit

z Input Under Voltage Lockout

z Thermal Shutdown

z RoHS Compliant and Halogen Free

Applications

z Industrial and Commercial Low Power Systems

z Computer Peripherals

z LCD Monitors and TVs

z Green Electronics/Appliances

z Point of Load Regulation for High-Performance DSPs,

FPGAs, and ASICs

Simplified Application Circuit

RT7277

VIN

C1 C2

Chip Enable

BOOT

PVCC

GND

DS7277-01 March 2013 www.richtek.com

PVCC

OUT

RT7277

Ordering Information

Pin Configurations

RT7277

Package Type SP : SOP-8 (Exposed Pad-Option 2)

Lead Plating System G : Green (Halogen Free and Pb Free)

Note :

Richtek products are :

` RoHS compliant and compatible with the current require-

ments of IPC/JEDEC J-STD-020.

` Suitable for use in SnPb or Pb-free soldering processes.

Functional Pin Description

Pin No. Pin Name Pin Function

1 EN

2 FB

3 PVCC

4 SS

5, 9

(Exposed Pad)

GND

Enable Input. A logic-high enables the converter; a logic-low forces the IC into shutdown mode reducing the supply current to less than 10μA.

Feedback Input. It is used to regulate the output of the converter to a set value via an external resistive voltage divider. The feedback threshold voltage is 0.765V typically.

Internal Regulator Output. Connect a 1μF capacitor to GND to stabilize output voltage.

Soft-Start Control Input. SS controls the soft-start period. Connect a capacitor from SS to GND to set the soft-start period. A 3.9nF capacitor sets the soft-start period of

to 2.6ms.

OUT

Ground. The Exposed pad should be soldered to a large PCB and connected to GND for maximum thermal dissipation.

(TOP VIEW)

PVCC

GND

SOP-8 (Exposed Pad)

VIN

BOOT

GND

6 SW Switch Node. Connect this pin to an external L-C filter.

7 BOOT

8 VIN

Bootstrap Supply for High Side Gate Driver. Connect a 0.1μF or greater ceramic capacitor from BOOT to SW pins.

Power Input. The input voltage range is from 4.5V to 18V. Must bypass with a suitably large ( ≥10μF x 2) ceramic capacitor.

DS7277-01 March 2013www.richtek.com

Function Block Diagram

RT7277

Operation

SS FB

PVCC

Internal

Regulator

VIBIAS

PVCC

On-Time

2µA

PVCC

REF

Ripple

Gen.

Over Current

Protection

Switch

Controller

Comparator

BOOT

PVCC

Driver

VIN

UGATE

LGATE

GND

In normal operation, the high side N-MOSFET is turned

on when the FB Comparator sets the Switch Controller,

and it is turned off when On-Time Controller resets the

Switch Controller. While the high side N-MOSFET is turned

off, the low side N-MOSFET is turned on and waits for the

FB Comparator to set the beginning of next cycle.

The FB Comparator sets the Switch Controller by

comparing the feedback signal (FB) from output voltage

with the internal 0.765V reference. When load transient

induces VOUT drop, the FB voltage will be less than its

threshold voltage. This means that the high side N-MOSFET

will turn on again immediately after minimum off-time

expired. The switching frequency will vary during the

transient period thus can provide a very fast transient

response. After the load transient finished, the RT7277

will be back to steady state with a constant switching

frequency.

Enable

Activate internal regulator once EN input level is higher

than the target level. Force IC to enter shutdown mode

when the EN input level is lower than 0.4V

Internal Regulator

Provide internal power for logic control and switch gate

drivers.

On-Time Controller

Control on-time according to VIN and SW to obtain

constant switching frequency.

DS7277-01 March 2013 www.richtek.com

RT7277

Absolute Maximum Ratings (Note 1)

z Supply Voltage, VIN ----------------------------------------------------------------------------------------------- −0.3V to 21V

z Switch Voltage, SW ----------------------------------------------------------------------------------------------- −0.8V to (V

<10ns ----------------------------------------------------------------------------------------------------------------- −5V to 25V

z BOOT to SW, PVCC ---------------------------------------------------------------------------------------------- −0.3V to 6V

z Other Pins Voltage ------------------------------------------------------------------------------------------------- −0.3V to 21V

z Power Dissipation, P

@ TA = 25°C

SOP-8 (Exposed Pad) -------------------------------------------------------------------------------------------- 2.041W

z Package Thermal Resistance (Note 2)

SOP-8 (Exposed Pad), θJA--------------------------------------------------------------------------------------- 49°C/W

SOP-8 (Exposed Pad), θJC-------------------------------------------------------------------------------------- 15°C/W

z Junction Temperature Range------------------------------------------------------------------------------------- 150°C

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

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

z ESD Susceptibility (Note 3)

HBM (Human Body Model)--------------------------------------------------------------------------------------- 2kV

+ 0.3V)

Recommended Operating Conditions

z Supply Voltage, VIN ----------------------------------------------------------------------------------------------- 4.5V to 18V

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

z Ambient Temperature Range------------------------------------------------------------------------------------- −40°C to 85°C

(Note 4)

Electrical Characteristics

(VIN = 12V, T

Supply Current

Shutdown Current I

Quiescent Current IQ V

Logic Threshold

EN Voltage

VFB Voltage and Discharge Resistance

Feedback Threshold Voltage VFB 4.5V ≤ V

Feedback Input Current IFB V

Output

PVCC

Output Voltage V

PVCC

Line Regulation 6V ≤ V Load Regulation 0 < I

Output Current I

= 25°C, unless otherwise specified)

Parameter Symbol Test Conditions Min Typ Max Unit

SHDN

= 0V -- 1.5 10 μA

= 3V, VFB = 1V -- 0.7 -- mA

Logic-High 2 -- 18

Logic-Low -- -- 0.4

≤ 18V 0.757 0.765 0.773 V

= 0.8V −0.1 0 0.1 μA

6V ≤ V

PVCC

≤ 18V, 0 < I

≤ 18V, I

< 5mA -- -- 100 mV

PVCC

= 6V, V

PVCC

= 4V -- 110 -- mA

PVCC

< 5mA 4.7 5.1 5.5 V

PVCC

= 5mA -- -- 20 mV

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RT7277

Parameter Symbol Test Conditions Min Typ Max Unit

Switch On Resistance

DS(ON)

High Side

DS(ON)_H

-- 90 --

mΩ

Low Side

DS(ON)_L

-- 60 --

Current Limit

Current Limit I

3.5 4.1 5.7 A

LIM

Thermal Shutdown

Thermal Shutdown Threshold TSD -- 150 -- °C Thermal Shutdown Hysteresis ΔTSD -- 20 -- °C

On-Time Timer Control

On-Time tON V

Minimum On-Time t

Minimum Off-Time t

ON(MIN)

OFF(MIN)

-- 60 -- ns

= 12V, V

= 1.05V -- 145 -- ns

OUT

-- 230 -- ns

Soft-Start

SS Charge Current VSS = 0V 1.4 2 2.6 μA

SS Discharge Current VSS = 0.5V 0.05 0.1 -- mA

UVLO

UVLO Threshold VIN Rising to Wake up V

3.55 3.85 4.15

PVCC

Hysteresis -- 0.3 --

Note 1. Stresses beyond those listed “Absolute Maximum Ratings” may cause permanent damage to the device. These are

stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in

the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions may

affect device reliability.

Note 2. θ

Note 3. Devices are ESD sensitive. Handling precaution is recommended. Note 4. The device is not guaranteed to function outside its operating conditions.

is measured at T

measured at the exposed pad of the package. The PCB copper area of exposed pad is 70mm

= 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. θJC is

DS7277-01 March 2013 www.richtek.com

RT7277

Typical Application Circuit

Chip Enable

(V) R1 (kΩ) R2 (kΩ) C3 (pF) L1 (μH) C7 (μF)

OUT

1 6.81 22.1 -- 1.4 22 to 68

1.05 8.25 22.1 -- 1.4 22 to 68

1.2 12.7 22.1 -- 1.4 22 to 68

1.8 30.1 22.1 5 to 22 2 22 to 68

2.5 49.9 22.1 5 to 22 2 22 to 68

3.3 73.2 22.1 5 to 22 2 22 to 68 5 124 22.1 5 to 22 3.3 22 to 68 7 180 22.1 5 to 22 3.3 22 to 68

C1 10µF x 2

5, 9 (Exposed Pad)

0.1µF

3.9nF

Table 1. Suggested Component Values

VIN

GND

RT7277

BOOT

PVCC

1.4µH

0.1µF

C4 1µF

PVCC

8.25k

22.1k

C7 22µF x 2

OUT

1.05V/3A

DS7277-01 March 2013www.richtek.com

Typical Operating Characteristics

RT7277

Efficiency vs. Output Current

100

= 5V

Efficiency (%)

0.001 0.01 0.1 1 10

= 12V

= 17V

Output Current (A)

Output Voltage vs. Temperature

1.065

1.060

1.055

1.050

1.045

1.040

Output Voltage (V)

1.035

OUT

= 1.05V

Output Voltage (V)

Output Voltage vs. Input Voltage

1.065

1.060

1.055

1.050

1.045

1.040

1.035

1.030

1.025 4 6 8 1012141618

OUT

Input Voltage (V)

Output Voltage v s . Output Current

1.065

1.060

1.055

1.050

= 17V

1.045

1.040

1.035

= 12V

= 5V

= 1.05V

1.030

1.025

-50 -25 0 25 50 75 100 125

= 12V, V

OUT

= 1.05V, I

OUT

= 0A

Temperature (°C)

Frequency vs. Input Voltage

750

740

730

720

710

700

690

680

Frequency (kHz) 1

670

660

650

4681012141618

Input Voltage (V)

Reference Voltage (V)

1.030

1.025

00.511.522.53

OUT

Output Current (A)

Reference Voltage vs. Temperature

0.785

0.780

0.775

0.770

0.765

0.760

0.755

0.750

0.745

-50 -25 0 25 50 75 100 125

Temperature (°C)

= 1.05V

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RT7277

Current Limit vs . Te m pe rature

6.0

5.6

5.2

4.8

Current Limit (A)

4.4

= 12V, V

4.0

-50-250 255075100125

OUT

Temperature (°C)

Load Transient Response

OUT

(2A/Div)

= 1.05V

6.0

5.5

5.0

4.5

4.0

Current Limit (A)

3.5

3.0

(10V/Div)

OUT

(10mV/Div)

Current Limit vs. Input Voltage

= 12V, V

4681012141618

OUT

= 1.05V

Input Voltage (V)

Switching

OUT

(20mV/Div)

(5V/Div)

OUT

(1V/Div)

OUT

(2A/Div)

= 12V, V

OUT

= 1.05V, I

Time (100μs/Div)

Power On from VIN

= 12V, V

Time (5ms/Div)

OUT

= 1.05V, I

= 0A to 3A

OUT

= 3A

(2A/Div)

(5V/Div)

OUT

(1V/Div)

OUT

(2A/Div)

= 12V, V

OUT

= 1.05V, I

Time (1μs/Div)

Power Off from VIN

= 12V, V

Time (10ms/Div)

OUT

= 1.05V, I

OUT

= 3A

DS7277-01 March 2013www.richtek.com

RT7277

(2V/Div)

OUT

(1V/Div)

OUT

(2A/Div)

EN Current (μA)

Power On from EN

= 12V, V

OUT

= 1.05V, I

OUT

Time (1ms/Div)

EN Current vs. EN Voltage

0 2 4 6 8 10 12 14 16 18

EN Voltage (V)

= 17V

= 3A

(2V/Div)

OUT

(1V/Div)

OUT

(2A/Div)

Power Off from EN

= 12V, V

Time (10μs/Div)

OUT

= 1.05V, I

OUT

= 3A

DS7277-01 March 2013 www.richtek.com

RT7277

Application Information

The RT7277 is a synchronous high voltage Buck converter

that can support the input voltage range from 4.5V to 18V

and the output current up to 3A. It adopts ACOTTM mode

control to provide a very fast transient response with few

external compensation components.

PWM Operation

It is suitable for low external component count

configuration with appropriate amount of Equivalent Series

Resistance (ESR) capacitors at the output. The output

ripple valley voltage is monitored at a feedback point

voltage. The synchronous high side MOSFET is turned

on at the beginning of each cycle. After the internal on-

time timer expires, the MOSFET is turned off. The pulse

width of this on-time is determined by the converter's input

and output voltages to keep the frequency fairly constant

over the entire input voltage range.

Advanced Constant On-Time Control

The RT7277 has a unique circuit which sets the on-time

by monitoring the input voltage and SW signal. The circuit

ensures the switching frequency operating at 700kHz over

input voltage range and loading range.

device again. For external timing control, the EN pin can

also be externally pulled high by adding a REN resistor

and CEN capacitor from the VIN pin (see Figure 1).

RT7277

GND

Figure 1. External Timing Control

An external MOSFET can be added to implement digital

control on the EN pin when no system voltage above 2V

is available, as shown in Figure 2. In this case, a 100kΩ

pull-up resistor, REN, is connected between VIN and the

EN pin. MOSFET Q1 will be under logic control to pull

down the EN pin.

100k

RT7277

GND

Figure 2. Digital Enable Control Circuit

Soft-Start

The RT7277 contains an external soft-start clamp that

gradually raises the output voltage. The soft-start timing

can be programmed by the external capacitor between

SS pin and GND. The chip provides a 2μA charge current

for the external capacitor. If a 3.9nF capacitor is used,

the soft-start will be 2.6ms (typ.). The available capacitance

range is from 2.7nF to 220nF.

t (ms) =

C5 (nF) 1.365

I (A)

Chip Enable Operation

The EN pin is the chip enable input. Pulling the EN pin

low (<0.4V) will shut down the device. During shutdown

mode, the RT7277 quiescent current drops to lower than

10μA. Driving the EN pin high (>2V, <18V) will turn on the

To prevent enabling circuit when VIN is smaller than the

target value, a resistive voltage divider can be placed

OUT

between the input voltage and ground and connected to

the EN pin to adjust IC lockout threshold, as shown in

Figure 3. For example, if an 8V output voltage is regulated

from a 12V input voltage, the resistor R

can be selected

EN2

to set input lockout threshold larger than 8V.

EN1

EN2

RT7277

GND

Figure 3. Resistor Divider for Lockout Threshold Setting

DS7277-01 March 2013www.richtek.com

RT7277

Output Voltage Setting

The resistive divider allows the FB pin to sense the output

voltage as shown in Figure 4.

OUT

RT7277

GND

Figure 4. Output Voltage Setting

The output voltage is set by an external resistive divider

according to the following equation. It is recommended to

use 1% tolerance or better divider resistors.

V = 0.765(1

OUT

×+

)

Under Voltage Lockout Protection

The RT7277 has Under Voltage Lockout Protection (UVLO)

that monitors the voltage of PVCC pin. When the V

PVCC

voltage is lower than UVLO threshold voltage, the RT7277

will be turned off in this state. This is non-latch protection.

inductor to achieve this goal. For the ripple current

selection, the value of ΔIL = 0.2(I

) will be a reasonable

MAX

starting point. The largest ripple current occurs at the

highest VIN. To guarantee that the ripple current stays

below the specified maximum, the inductor value should

be chosen according to the following equation :

⎡⎤⎡ ⎤

L = 1

OUT OUT

⎢⎥⎢ ⎥

fI V

×Δ

L(MAX) IN(MAX)

⎣⎦⎣ ⎦

×−

Input and Output Capacitors Selection

The input capacitance, CIN, is needed to filter the

trapezoidal current at the source of the high side MOSFET.

A low ESR input capacitor with larger ripple current rating

should be used for the maximum RMS current. The RMS

current is given by :

I = I 1

RMS OUT(MAX)

OUT

This formula has a maximum at VIN = 2V

RMS

= I

/ 2. This simple worst-case condition is

OUT

IN OUT

−

, where

OUT

commonly used for design because even significant

deviations do not offer much relief.

Over Temperature Protection

The RT7277 equips an Over Temperature Protection (OTP)

circuitry to prevent overheating due to excessive power

dissipation. The OTP will shut down switching operation

when junction temperature exceeds 150°C. Once the

junction temperature cools down by approximately 20°C

the main converter will resume operation. To keep operating

at maximum, the junction temperature should be prevented

from rising above 150°C.

Inductor Selection

The inductor value and operating frequency determine the

ripple current according to a specific input and an output

voltage. The ripple current ΔIL increases with higher V

and decreases with higher inductance.

⎡⎤⎡ ⎤

OUT OUT

I = 1

Δ×−

⎢⎥⎢ ⎥

fL V

⎣⎦⎣ ⎦

Having a lower ripple current reduces not only the ESR

losses in the output capacitors but also the output voltage

ripple. High frequency with small ripple current can achieve

highest efficiency operation. However, it requires a large

Choose a capacitor rated at a higher temperature than

required. Several capacitors may also be paralleled to

meet size or height requirements in the design. For the

input capacitor, two 10μF and 0.1μF low ESR ceramic

capacitors are recommended.

The selection of C

is determined by the required ESR

OUT

to minimize voltage ripple.

Moreover, the amount of bulk capacitance is also a key

for C

The output ripple, ΔV

Δ≤Δ +

selection to ensure that the control loop is stable.

OUT

, is determined by :

OUT

8fC

OUT

VIESR

OUT L

⎡⎤ ⎢⎥

⎣⎦

The output ripple will be highest at the maximum input

voltage since ΔIL increases with input voltage. Multiple

capacitors placed in parallel may need to meet the ESR

and RMS current handling requirements.

Higher values, lower cost ceramic capacitors are now

becoming available in smaller case sizes. Their high ripple

current, high voltage rating and low ESR make them ideal

for switching regulator applications. However, care must

be taken when these capacitors are used at input and

DS7277-01 March 2013 www.richtek.com

RT7277

output. When a ceramic capacitor is used at the input

and the power is supplied by a wall adapter through long

wires, a load step at the output can induce ringing at the

input, VIN. A sudden inrush of current through the long

wires can potentially cause a voltage spike at VIN large

enough to damage the part.

External Bootstrap Diode

Connect a 0.1μF low ESR ceramic capacitor between the

BOOT and SW pins. This capacitor provides the gate driver

voltage for the high side MOSFET. It is recommended to

add an external bootstrap diode between an external 5V

and the BOOT pin for efficiency improvement when input

voltage is lower than 5.5V or duty ratio is higher than 65%.

The bootstrap diode can be a low cost one such as 1N4148

or BAT54. The external 5V can be a 5V fixed input from

system or a 5V output of the RT7277. Note that the external

boot voltage must be lower than 5.5V

Thermal Considerations

For continuous operation, do not exceed absolute

maximum junction temperature. The maximum power

dissipation depends on the thermal resistance of the IC

package, PCB layout, rate of surrounding airflow, and

difference between junction and ambient temperature. The

maximum power dissipation can be calculated by the

following formula :

where T

the ambient temperature, and θ

D(MAX)

= (T

J(MAX)

− TA) / θ

J(MAX)

is the maximum junction temperature, T

is the junction to ambient

thermal resistance.

For recommended operating condition specifications, the

maximum junction temperature is 125°C. The junction to

ambient thermal resistance, θJA, is layout dependent. For

SOP-8 (Exposed Pad) package, the thermal resistance,

θJA, is 49°C/W on a standard JEDEC 51-7 four-layer

thermal test board. The maximum power dissipation at

TA = 25°C can be calculated by the following formulas :

BOOT

RT7277

0.1µF

Figure 5. External Bootstrap Diode

PVCC Capacitor Selection

Decouple with a 1μF ceramic capacitor. X7R or X5R grade

dielectric ceramic capacitors are recommended for their

stable temperature characteristics.

Over Current Protection

When the output shorts to ground, the inductor current

decays very slowly during a single switching cycle. An

over current detector is used to monitor inductor current

to prevent current runaway. The over current detector

monitors the voltage between SW and GND during the

low side MOS turn-on state. This is cycle-by-cycle

protection. The over current detector also supports

temperature compensated.

= (125°C − 25°C) / (49°C/W) = 2.041W for

D(MAX)

SOP-8 (Exposed Pad) package

The maximum power dissipation depends on the operating

ambient temperature for fixed T

and thermal

J(MAX)

resistance, θJA. The derating curve in Figure 6 allow the

designer to see the effect of rising ambient temperature

on the maximum power dissipation.

2.5

2.0

1.5

1.0

0.5

Maximum Power Dissipation (W) 1

0.0 0 25 50 75 100 125

Ambient Temperature (°C)

Four-Layer PCB

Figure 6. Derating Curve of Maximum Power Dissipation

DS7277-01 March 2013www.richtek.com

Layout Consideration

Follow the PCB layout guidelines for optimal performance

of the RT7277

` Keep the traces of the main current paths as short and

wide as possible.

` Put the input capacitor as close as possible to the device

pins (VIN and GND).

RT7277

` SW node is with high frequency voltage swing and

should be kept at small area. Keep sensitive

components away from the SW node to prevent stray

capacitive noise pickup.

` Connect feedback network behind the output capacitors.

Keep the loop area small. Place the feedback

components near the RT7277 feedback pin.

` The GND and Exposed Pad should be connected to a

strong ground plane for heat sinking and noise protection.

The resistor divider must be connected as close to the device as possible.

OUT

GND

PVCC

Input capacitor must be placed

as close to the IC as possible.

VIN

GND

BOOT

GND

Figure 7. PCB Layout Guide

SW should be connected to inductor by wide and short trace. Keep sensitive components away from this trace.

OUT

DS7277-01 March 2013 www.richtek.com

RT7277

Outline Dimension

EXPOSED THERMAL PAD (Bottom of Package)

Dimensions In Millimeters Dime nsions In Inches

Symbol

Min Max Min Max

A 4.801 5.004 0.189 0.197

B 3.810 4.000 0.150 0.157

C 1.346 1.753 0.053 0.069

D 0.330 0.510 0.013 0.020

F 1.194 1.346 0.047 0.053

H 0.170 0.254 0.007 0.010

I 0.000 0.152 0.000 0.006

J 5.791 6.200 0.228 0.244

M 0.406 1.270 0.016 0.050

X 2.000 2.300 0.079 0.091

Option 1

Y 2.000 2.300 0.079 0.091

X 2.100 2.500 0.083 0.098

Option 2

Y 3.000 3.500 0.118 0.138

8-Lead SOP (Exposed Pad) Plastic Package

Richtek Technology Corporation

5F, No. 20, Taiyuen Street, Chupei City

Hsinchu, Taiwan, R.O.C.

Tel: (8863)5526789

Richtek products are sold by description only. Richtek reserves the right to change the circuitry and/or specifications without notice at any time. Customers should

obtain the latest relevant information and data sheets before placing orders and should verify that such information is current and complete. Richtek cannot

assume responsibility for use of any circuitry other than circuitry entirely embodied in a Richtek product. Information furnished by Richtek is believed to be

accurate and reliable. However, no responsibility is assumed by Richtek or its subsidiaries for its use; nor for any infringements of patents or other rights of third

parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Richtek or its subsidiaries.

DS7277-01 March 2013www.richtek.com

Richtek RT7277GSP Schematic [ru]

Specifications and Main Features

Frequently Asked Questions

User Manual