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DS8241-03   January  2014

www.richtek.com

RT8241

©

Copyright   2014 Richtek Technology Corporation. All rights reserved.                          is a registered trademark of Richtek Technology Corporation.

Parameter Symbol  Test 

Conditions  Min 

Typ 

Max 

Unit 

Current Sensing

 

CS Source Current 

 

 

10 

11 

μ

CS Source Current 
Temperature Coefficient 

 

 

-- 4700 -- ppm/

°

Zero Crossing Threshold 

 

PHASE 

− 

GND 

10 

-- 5 mV 

Protection Function 

Current Limit Threshold 
Offset 

 GND 

− 

PHASE = VCS/8 

20 0 20 mV 

Negative Current Limit 
Threshold Offset 

 PHASE 

− 

GND 

VCS/8 

-- 3 -- mV 

Under Voltage Protection     

UVP Detect, Falling Edge 

0.41 

0.45 

0.49 

UVP Fault Delay 

 

V

FB

 

0.375V 

-- 3.5 -- 

μ

Over Voltage Protection 

 

OVP Detect, Rising Edge 

1.065 

1.1 

1.133 

OVP Fault Delay 

 

V

FB

 

1.183V 

-- 5 -- 

μ

V

CC

 Under Voltage Lockout 

(UVLO) Threshold 

V

UVLO

 

Falling edge, PWM disabled below 
this level 

3.5 3.7 3.9  V 

V

CC

 UVLO Hysteresis 

Δ

V

UVLO

 

 

-- 100 --  mV 

VOUT Soft-Start 

 

From EN = High to V

OUT

 = 95% 

-- 

0.8 

-- 

ms 

Dynamic VID Slew Rate 

S

GX

 G0/G1 

Transition 

1.75 

-- 

10 

mV/

μ

UVP Blank Time 

 

From EN signal going high 

-- 

ms 

Thermal Shutdown 

T

SD

 

 

-- 150 -- 

Thermal Shutdown 
Hysteresis 

Δ

T

SD

   

-- 10 -- 

°

Driver On-Resistance 

UGATE Driver Source 

R

UGATEsr

 

BOOT

PHASE forced to 5V, 

UGATE High State 

-- 1.8 3.6 

Ω

 

UGATE Driver Sink 

R

UGATEsk

 

BOOT

PHASE forced to 5V, 

UGATE Low State 

-- 1.2 2.4 

Ω

 

LGATE Driver Source 

R

LGATEsr

 

LGATE, High State   

-- 1.8 3.6 

Ω

 

LGATE Driver Sink 

R

LGATEsk

 

LGATE, Low State   

-- 0.8 

1.34 

Ω

 

LGATE Rising (V

PHASE

 = 1.5V) 

-- 

30 

-- 

Dead Time 

 

UGATE Rising   

-- 

30 

-- 

ns 

Internal Boost Charging 
Switch On-Resistance 

 

VCC to BOOT, 10mA 

-- 

-- 

80 

Ω

 

EN Threshold

 

Logic-High  V

IH

 

 1.8 

-- 

-- 

EN Threshold 
Voltage  

Logic-Low  V

IL

 

 -- 

-- 

0.5 

Voltage Programming (G0, G1)

 

Logic-High  

 

750 

-- 

-- 

G0, G1 Input 
Threshold 
Voltage 

Logic-Low  

 

-- 

-- 

300 

mV 

 

Summary of Contents for RT8241

Page 1: ...n high voltage batteries at the highest possible efficiency The RT8241 is intended for CPU core chipset DRAM or other low voltage supplies as low as 0 675V The RT8241 is available in a WQFN 12L 2x2 pa...

Page 2: ...LOUT 8 G1 VIN CIN VOUT COUT Optional R2 Chip Enable VCC RT8241 VCC 5 9 6 PGOOD EN 11 CS 12 13 Exposed Pad GND 4 BOOT 3 2 1 7 10 UGATE PHASE LGATE G0 FB R1 CBYPASS RCS R3 C1 R4 Q1 Q2 R5 C2 LOUT 8 G1 VI...

Page 3: ...d the bootstrap circuit for high side driver Bypass to GND with a 4 7 F ceramic capacitor 6 EN Chip Enable Active High 7 G0 2 Bit Input Pin 8 G1 2 Bit Input Pin 9 PGOOD Open Drain Power Good Indicator...

Page 4: ...C to 150 C z ESD Susceptibility Note 3 HBM Human Body Mode 2kV MM Machine Mode 200V Recommended Operating Conditions Note 4 z Supply Input Voltage VIN 4 5V to 26V z Control Voltage VCC 4 5V to 5 5V z...

Page 5: ...er Voltage Lockout UVLO Threshold VUVLO Falling edge PWM disabled below this level 3 5 3 7 3 9 V VCC UVLO Hysteresis VUVLO 100 mV VOUT Soft Start From EN High to VOUT 95 0 8 ms Dynamic VID Slew Rate S...

Page 6: ...1 A Note 1 Stresses listed as the above Absolute Maximum Ratings may cause permanent damage to the device These are for stress ratings Functional operation of the device at these or any other conditi...

Page 7: ...Frequency kHz 1 VIN 8V VCC VEN 5V VOUT 0 9V Efficiency vs Output Current 60 65 70 75 80 85 90 95 100 0 001 0 01 0 1 1 10 Output Current A Efficiency VIN 12V VCC VEN 5V VOUT 0 9V Switching Frequency vs...

Page 8: ...V VCC VEN 5V VOUT 0 8V to 0 9V VOUT 50mV Div 0 9V Shutdown Current vs Input Voltage 0 0 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 1 0 5 7 9 11 13 15 17 19 21 23 25 Input Voltage V Shutdown Current A 1 NoLoa...

Page 9: ...ransient Response Time 100 s Div VIN 12V VCC VEN 5V VOUT 0 9V ILOAD 0A to 6A ILOAD 5A Div VOUT_ac 20mV Div LGATE 10V Div UGATE 20V Div Over Voltage Protection PGOOD 5V Div VOUT 500mV Div LGATE 5V Div...

Page 10: ...this capacitor to charge from zero volts to VOUT thereby making the on time of the high side switch directly proportional to the output voltage and inversely proportional to the input voltage The imp...

Page 11: ...trigger NOCP the low side MOSFET will be turned off to prevent Figure 3 Output Voltage Down Transition LGATE PHASE UGATE FB G0 G1 G0 G1 Q1 Q2 CIN VIN RFB1 RFB2 BOOT VOUT COUT For an upward transition...

Page 12: ...e CS trip CS CS V mV R k 10 A The Inductor current can be monitored by the voltage between GND and the PHASE pin Hence the PHASE pin should be connected to the drain terminal of the low side MOSFET IC...

Page 13: ...e MOSFET without degrading the turn off time as shown in Figure 7 Figure 7 Reducing the UGATE Rise Time PHASE UGATE Q1 CIN VIN BOOT R Power Good Output PGOOD The power good output is an open drain out...

Page 14: ...nd cause erratic and unstable operation However it is easy to add sufficient series resistance by placing the capacitors a couple of inches downstream from the inductor and connecting FB divider close...

Page 15: ...ines should be strictly followed Connect an RC low pass filter from VCC 1 F and 10 are recommended Place the filter capacitor close to the IC Keep current limit setting network as close as possible to...

Page 16: ...ccurate 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...

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