Richtek RT8239A, Manual

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RT8239A/B/C
8
DS8239A/B/C-06 October 2012 www.richtek.com
© Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation.
Parameter Symbol Test Conditions Min Typ Max Unit
Output Voltage Adjustable
Range
SMPS1, SMPS2 2 -- 5.5
SECFB Voltage
V
SECFB
RT8239B 1.92 2 2.08
V
On-Time
V
PHASE1
= 2V
-- 256 --
On-Time Pulse Width
t
UGATEx
V
IN
= 20V
R
TON
= 56k
Ω
V
PHASE2
= 2V
-- 220 --
ns
Minimum Off-Time
t
LGATEx
V
FBx
= 1.8V
-- -- 400 ns
f
SMPS1
SMPS1 Operating Frequency 200 -- 400
Frequency Range
f
SMPS2
SMPS2 Operating Frequency 233 -- 466
kHz
Ultrasonic Mode Frequency f
ASM
RT8239C, V
PHASEx
= 50mV
25 -- -- kHz
Soft-Start
Soft-Start Time
t
SSx
Zero to 200mV Current Limit Threshold
from ENTRIPx Enable
-- 2 -- ms
Current Sense
Current Limit Current Source I
ENTRIPx
V
ENTRIPx
= 0.9V
9.4 10 10.6
μ
A
Temperature Coefficient of
I
ENTRIPx
On The Basis of 25
°
C
-- 4700 -- ppm/
°
C
Current Limit Adjustment
Range
V
ENTRIPx
= I
ENTRIPx
x R
ENTRIPx
0.5 -- 2.7 V
Current Limit Threshold
V
ENTRIPx
GND
−
PHASEx, V
ENTRIPx
= 2V
180 200 225 mV
Zero-Current Threshold
V
ZC
GND
−
PHASEx, FBx = 2.1V -- 3 -- mV
Internal Regulator and Reference
V
BYP1
= 0V, I
LDO5
< 100mA
4.8 5 5.2
V
BYP1
= 0V, I
LDO5
< 100mA ,
6.5V < V
IN
< 25V
4.75 -- 5.25
LDO5 Output Voltage
V
LDO5
V
BYP1
= 0V, I
LDO5
< 50mA,
5.5V < V
IN
< 25V
4.75 -- 5.25
V
LDO5 Output Current I
SHORT5
V
BYP1
= 0V, V
LDO5
= 4.5V -- 225 -- mA
5V Switchover Threshold V
BYP1TH
Falling Edge, Rising Edge with FB1
Regulation Point
4.53 4.66 4.79 V
5V Switch R
DS(ON)
R
BYPSW
V
BYP1
= 5V, I
LDO5
= 50mA -- 1.5 3
Ω
V
BYP1
= 0V, I
LDO3
< 100mA 3.2 3.3 3.46 V
LDO3 Output Voltage V
LDO3
V
BYP1
= 5V, I
LDO3
< 100mA 3.2 3.3 3.46
LDO3 Output Current I
SHORT3
V
BYP1
= 0V, V
LDO3
= 2.9V -- 150 -- mA
UVLO
Rising Edge -- 4.35 4.5
LDO5 UVLO Threshold V
UVLO5
Falling Edge 3.9 4.05 4.2
V
LDO3 UVLO Threshold V
UVLO3
Both SMPS Off -- 2.2 --
Power Good
PGOOD Threshold V
PGOOD
PGOOD Detect, Rising edge with
soft-start delay time. Hysteresis = 2.5%
−
14
−
10
−
6 %
PGOOD Propagation Delay t
PD_PGOOD
Falling Edge -- 5 --
μ
s