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RT9224
5-Bit Programmable Synchronous PWM Buck Converter
Controller and Output Voltage Monitor
General Description
The RT9224 is a high speed switching controller
designed for use in synchronous DC/DC buck
converter for modern CPUs. The regulated output
voltage is digitally programmable from 1.3V to 3.5V
by a 5-bit DAC which provides initial accuracy of
±1%. The RT9224 drives two external N-channel
MOSFETs, providing high efficiency and eliminating
the need for high cost P-channel devices. It senses
the output current across the on-resistance of the
upper N-channel MOSFET and provides an
adjustable current limit without external sense
resistor.
RT9224 monitors the output voltage and provides
the output signal for power-good and over-voltage
protection. The switching controller drivers two N-
MOSFETs at 200kHz frequency and provides an
optimal solution for size, efficiency and cost in any
application circuits. The high switching frequency
cooperating with a high speed error amplifier
maintains a fast response to the dynamic load of
modern CPUs.
Ordering Information
RT9224
Package type
S : SOP-20
Operating temperature range
C: Commercial standard
Features
z
Compatible with HIP6004B
z
Simple Voltage-mode PWM Control with Buck
Rectification
z
±1% DAC Output Voltage Accuracy
z
5-Bit Digital-to-Analog Output Voltage Range
from 1.3 V to 3.5V
z
Fast Transient Response and Excellent Output
Voltage Regulation
z
Fault Protection for Over-voltage and Over-
current
z
Power-good Output Voltage Monitor
z
Fixed 200kHz Switching Frequency
Applications
Power Supply for Pentium, Pentium ProTM,
z
Pentium II
Alpha
Low-voltage Distributed Power Supplies
z
High Power 5V to 1.3V~3.5V Switching Regulator
z
TM
TM
, PowerPCTM, K6TM, 6x86TM, and
Microprocessors
Pin Configurations
Part Number Pin Configurations
RT9224CS
(Plastic SOP-20)
VSEN
OCSET
SS
VID0
VID1
VID2
VID3
VID4
NC
FB
TOP VIEW
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
NC
OVP
VCC
LGATE
PGND
BOOT
UGATE
PHASE
PGOOD
GND
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RT9224
Absolute Maximum Ratings
Supply Voltage +15V
z
Boot Voltage +15V
z
Input, Output or I/O Voltage GND – 0.3V to Vcc + 0.3V
z
Storage Temperature Range -65°C ~150°C
z
Package Thermal Resistance
z
SOP-20,θ
JA
Recommended Operating Conditions
87°C/W
Supply Voltage, V
z
Ambient Temperature Range 0°C to 70°C
z
Junction Temperature Range 0°C to 125°C
z
CC
+12V±10%
Electrical Characteristics
(T
= 25°C, recommended operating conditions, unless otherwise specified)
A
Parameter Symbol Test Conditions Min Typ Max Units
VCC Supply Current
Nominal Supply
I
CC
UGATE and LGATE Open
Power-On Reset
VCC Rising Threshold
VCC Falling Threshold
Rising V
OCSET
Threshold
V
OCSET
V
OCSET
= 4.5V
= 4.5V
Oscillator
Free Running Frequency 170 200 230
Ramp Amplitude
∆V
OSC
Reference and DAC
DAC (VID0 – VID4) Input Low Voltage -- -- 0.8
--
3--mA
-- 9.5 -- V
-- 7.5 -- V
-- 1.6 -- V
-- 1.9 --
KHz
V
P-P
V
DAC (VID0 – VID4) Input High Voltage 2.0 -- --
DACOUT Voltage Accuracy -1.0 -- +1.0
V
%
Error Amplifier
DC Gain -- 65 --
dB
Gate Drivers
UGATE Source
UGATE Sink
LGATE Source
LGATE Sink
R
UGATEVBOOT
R
UGATEVUGATE
I
LGATE
R
LGATEVLGATE
VCC = 12V, V
- V
- V
= 1V
PHASE
PHASE
LGATE
= 12V
= 1V
= 6V
-- 8 --
-- 5 --
-- 500 --
-- 5 --
Ω
Ω
mA
Ω
To be continued
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Protection
RT9224
Parameter Symbol Test Conditions Min Typ Max Units
Over-voltage Trip (VSEN/DACOUT) -- 115 120
OCSET Current Source
OVP Sourcing Current
Soft-Start Current
I
OCSETVOCSET
I
OVP
I
SS
V
SEN
VSS = 1.5V
= 4.5V
= 5.5V, V
OVP
= 0V
167 200 233
60 -- --
-- 10 --
Power Good
Upper Threshold (VSEN/DACOUT) VSEN Rising 106 -- 114
Lower Threshold (VSEN/DACOUT) VSEN Falling 89 -- 96
Hysteresis (VSEN/DACOUT) Upper and Lower Threshold -- 2 --
PGOOD Voltage Low
V
PGOODIPGOOD
= -5mA
-- 0.5 --
Function Block Diagram
VCC
VSEN
OCSET
REFE RENCE
110%
90%
115%
200µA
+
_
+
_
OVER-
VOLTAGE
+
_
+
_
OVER-
CURRENT
4. 5V
POWER-ON
RESET (POR)
SOFT-
START
PGOOD
OVP
10µA
SS
BOOT
UGATE
%
µA
mA
µA
%
%
%
V
VID0
VID1
VID2
VID3
VID25
FB
DS9224-04 July 2001 www.richtek-ic.com.tw
TTL D/A
CONVERTER
(DAC)
DACO UT
ERRO R
AMP
+
OSCILLATOR
PWM
COMPARATOR
+
_
_
INHIB IT
GATE
CONTROL
LO GIC
PWM
PHASE
LG ATE
PGND
GND
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RT9224
Pin Description
Pin No. Pin Name Pin Function
1VSEN
2 OCSET
3SS
4VID0
5VID1
6VID2
7VID3
8VID4
9NC
10 FB
11 GND
12 PGOOD
Output voltage monitoring input for OVP & PGOOD
Over current set pin, sinks 200µA through a resistor (R
MOSFET to set the trip point:
200µA × R
I
=
PEAK
An over-current trip cycles the soft-start function
Soft start speed is set by internal 10µA current source and capacitor from this pin to GND
Switching Regulator Output Voltage Setting
Switching Regulator Output Voltage Setting
Switching Regulator Output Voltage Setting
Switching Regulator Output Voltage Setting
Switching Regulator Output Voltage Setting
No Connection
Feedback input pin for the PWM Loop
IC Signal Ground
Open Drain Logic Output
This pin is pulled low when the converter output is not within ±10% of the DACOUT
reference voltage
MOSFET-on resistance
OCS
) from this pin to upper N-
OCS
13 PHASE
14 UGATE
15 BOOT
16 PGND
17 LGATE
18 VCC
19 OVP
20 NC No Connection
Current Limit Sense Input
High Side Driver Output
Driver Power
Low Side Driver GND
Low Side Driver Output
Power Supply Input
Over Voltage Protection
This pin is pulled high when the VSEN voltage is over 15% of the DACOUT reference
voltage
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Table 1 Output Voltage Program
RT9224
Pin Name Pin Name
VID4 VID3 VID2 VID1 VID0
01111 1.30V 11111 2.0V
01110 1.35V 11110 2.1V
01101 1.40V 11101 2.2V
01100 1.45V 11100 2.3V
01011 1.50V 11011 2.4V
01010 1.55V 11010 2.5V
01001 1.60V 11001 2.6V
01000 1.65V 11000 2.7V
00111 1.70V 10111 2.8V
00110 1.75V 10110 2.9V
00101 1.80V 10101 3.0V
00100 1.85V 10100 3.1V
00011 1.90V 10011 3.2V
Nominal Output
Voltage DACOUT
VID4 VID3 VID2 VID1 VID0
Nominal
Output Voltage
DACOUT
00010 1.95V 10010 3.3V
00001 2.00V 10001 3.4V
00000 2.05V 10000 3.5V
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RT9224
Typical Application Circuit
L1
VIN = 5V
F1
1µHC
+
IN
5×1000µF
2N6394
2×1µF
+12V
0.1µF
VSEN
VID0
VID1
VID2
VID3
VID4
10
Ω
0.1µF
SS
10
2K
15V
OVPVCC
18
3
1
4
5
6
7
8
MONITOR AND
PROTECTION
OSC
D/A
_
+
19
_
+
FB
OCSET
2
12
15
14
13
17
16
11
GND
PGOOD
BOOT
UGATE
PHASE
LGATE
PGND
1000pF
1K
D2
Q2
Q1
L2 - 3µH
C
OUT
9×1000µF
4.99K
0.68µF
750K
+V
O
+
Component Selection Notes:
C
, CIN– Each 1000µF 6.3W VDC, Sanyo MV-GX or Equivalent.
OUT
L2 – Core: Micrometals T50-52B; Winding: 10 Turns of 16AWG.
L1 – Core: Micrometals T50-52; Winding: 5 Turns of 18AWG.
D2 – 3A, 40V Schottky, Motorola MBR340 or Equivalent.
Q1, Q2 – PHB83N03LT; PHB95N03LT
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Package Information
RT9224
H
M
B
A
C
FD
Dimensions In Millimeters Dimensions In Inches
Symbol
Min Max Min Max
A 12.598 13.005 0.496 0.512
B 7.391 7.595 0.291 0.299
C 2.362 2.642 0.093 0.104
D 0.330 0.508 0.013 0.020
F 1.194 1.346 0.047 0.053
I
B
J
H 0.229 0.330 0.009 0.013
I 0.102 0.305 0.004 0.012
J 10.008 10.643 0.394 0.419
M 0.381 1.270
DS9224-04 July 2001 www.richtek-ic.com.tw
0.015 0.050
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RT9224
RICHTEK TECHNOLOGY CORP.
Headquarter
6F, No. 35, Hsintai Road, Chupei City
Hsinchu, Taiwan, R.O.C.
Tel: (8863)5510047 Fax: (8863)5537749
www.richtek-ic.com.tw DS9224-04 July 2001
RICHTEK TECHNOLOGY CORP.
Taipei Office (Marketing)
8F-1, No. 137, Lane 235, Paochiao Road, Hsintien City
Taipei County, Taiwan, R.O.C.
Tel: (8862)89191466 Fax: (8862)89191465
Email: marketing@richtek-ic.com.tw
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