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PDF RT9237 Data sheet ( Hoja de datos )
| Número de pieza | RT9237 | |
| Descripción | MULTI-PHASE DC/DC CONTROLLER | |
| Fabricantes | Richtek | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de RT9237 (archivo pdf) en la parte inferior de esta página. Total 15 Páginas | ||
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Preliminary
RT9237
Multi-Phase DC/DC Controller for CPU Core Power Supply
General Description
wwwT.dhaetaRshTe9et243u.7coims a multi-phase buck DC/DC controller
integrated with all control functions for high
performance processor VRM. The RT9237 drives 2,
3 or 4 buck switching stages operating in interleaved
phase set automatically. The multi-phase
architecture provides high output current while
maintaining low power dissipation on power devices
and low stress on input and output capacitors. The
high equivalent operating frequency also reduces
the component dimension and the output voltage
ripple in load transient.
RT9237 regulates both easily set voltage and
current loops. Precise current sharing for power
stage is achieved by differential input current sense
and processing circuit. The settings of current
sense, droop tuning and over current protection are
independent to compensation circuit of voltage loop.
The feature greatly facilitates the flexibility of CPU
power supply design and tuning.
The RT9237 uses a 5-bit DAC of 1.1V to 1.85V
(25mV/step) output with load current droop
compensation to meet the strict VRM transient
requirement. The IC monitors the VCORE voltage
for PGOOD and over voltage protection. Soft start,
over current protection and programmable under
voltage lockout are also provided to assure the
safety of microprocessor and power system.
Applications
z Power Supply for Server and Workstation
z Power Supply for High Current Microprocessor
Ordering Information
RT9237
Package Type
S : SOP-28
Operating temperature range
C: Commercial standard
Features
z Multi-Phase Power Conversion with Automatic
Phase Selection
z VRM 9.0 DAC Output with Active Droop
Compensation for Fast Load Transient
z Precise Channel Current Sharing with
Differential Sense Input
z Hiccup Mode Over Current Protection
z Programmable Under Voltage Lockout and
Soft Start
z High Ripple Frequency, (Channel Frequency
200KHz) Times Channel Number
Pin Configurations
Part Number
Pin Configurations
RT9237CS
(Plastic SOP-28)
TOP VIEW
VID4 1
VID3 2
VID2 3
VID1 4
VID0 5
COMP 6
FB 7
ADJ 8
GND 9
VSEN 10
IRMP 11
DVD 12
28 VDD
27 PGOOD
26 PWM4
25 ISP4
24 ISP1
23 PWM1
22 PWM2
21 ISP2
20 ISP3
19 PWM3
18 ISN1
17 ISN2
IMAX 13
SS 14
16 ISN3
15 ISN4
DS9237-00 January 2002
www.richtek-ic.com.tw
1
1 page  
Typical Application Circuit
Preliminary
www.datasheet4u.com
RT9237
DS9237-00 January 2002
www.richtek-ic.com.tw
5
5 Page 
Preliminary
RT9237
Design Example
Three phase converter VCORE = 1.5V, VIN = 12V, full
load current = 60Amp, droop voltage at full load =
www1.2da0tmasVhe,etO4uC.cPom trip point for each power stage =
30Amp (at Sample/Hold), low side MOSFET RDS(ON)
= 6mΩ at room temperature, L = 2µH, COUT =
9000µF, capacitor ESR = 2m Ω.
1. Compensation setting
a. Modulator Gain, Pole and Zero
Modulator Gain =
VIN
VRAMP
, saw-tooth wave
amplitude
VRAMP
=
1V
×
56kΩ
RIMP
, choose RIRMP
= 39K, VRAMP = 1.4V, modulator Gain = 8.6 =
1
18.7dB, LC
ESR zero =
filter pole
1
2
πCRESR
=
=
2π LC
8.8kHz
= 1.2kHz
,
b. EA compensation network
Use type 2 compensation scheme (see Fig. 5),
,FZ
=
1
2πR2C1
,
mid-band gain
FP =
=
R2
R1
1
2πR2(
C1
C1
×
+
. Choose
C2
C2
R1
)
=
2.4KΩ,
R2
=
24KΩ, C1 = 6.6nF, C2 = 33pF, get FZ = 1KHz,
Fp = 200KHz, mid-band Gain=10=20dB,
modulator asymptotic Bode plot of EA
compensation and PWM loop Gain Bode
shown as Fig. 6.
C1 R2
C2
COMP
_
EA
FB
DACOUT
C3 R3
R1
VCORE
R3, C3 are used in type 3
compensation scheme (left
NC in type 2)
ROL
ROL for no load offset
setting
Fig. 5 EA Compensation Network
Asymptotic Bode Plot of PWM Loop Gain
100
80
60
Uncompensated EA Gain
40
20
0
Compensated EA Gain
-20 PWM Loop Gain
-40 Modulator Gain
-60
1100
110000
110K00
11000K00 10100000K0 1010M0000 1010000M000
Frequency (Hz)
Fig. 6 Asymptotic Bode Plot of PWM Loop Gain
2. Droop setting
Full load current of each power channel = 60A/3 =
20Amp, the ripple current = ∆IL =
5µS
×
1.5V
2µH
×
1 −
1.5V
12V
=
3.28A
, load current at S/H =
20A −
∆IL
2
= 18.36A , GM
Amp S/H
IX(MAX )
=
RDS(ON) × 18.36A
RSP
,
suggested
IX
at full = 40µA〜50µA, choose RSP = RSN = 2.7KΩ,
IX(MAX) = 40.8µA, required Droop = 120mV =
40.8µA×3×2/3×RADJ ，RADJ = 1.47KΩ.
Take the temperature rising for consideration, if
MOSFET working temperature=70°C and the
temperature coefficient =5000ppm/°C, the
RDS(ON)(70°C) = 6mΩ × {1+(70°C-27°C) ×
5000ppm/°C} = 7.3 mΩ, RADJ(70°C) = RADJ(27°C)
× {RDS(ON)(27°C)/RDS(ON)(70°C)} = 1.21KΩ
3. Over Current Protection setting
OCP trip point current = 30A (at Sample/Hold)，
IX
=
RDS(ON) × 30A
RSP
=
3
2
0.6V
× RIMAX
，RIMAX=13.6KΩ
Take the temperature rising for consideration,
RIMAX(70°C) = RIMAX(27°C) ×
{RDS(ON)(27°C)/RDS(ON)(70°C)} = 11.2KΩ
4. SS capacitor
CSS = 0.1µF is the suitable value for most
application.
DS9237-00 January 2002
www.richtek-ic.com.tw
11
11 Page | ||
| Páginas | Total 15 Páginas | |
| PDF Descargar | [ Datasheet RT9237.PDF ] | |
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