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參數(shù)資料
| 型號： | ISL6523A |
| 廠商： | Intersil Corporation |
| 英文描述： | Adjustable Precision Shunt Regulator 3-SOT-89 0 to 70 |
| 中文描述： | VRM8.5雙雙PWM和線性電源系統(tǒng)控制器 |
| 文件頁數(shù)： | 10/16頁 |
| 文件大小： | 408K |
| 代理商： | ISL6523A |
10
Layout Considerations
MOSFETs switch very fast and efficiently. The speed with
which the current transitions from one device to another
causes voltage spikes across the interconnecting
impedances and parasitic circuit elements. The voltage
spikes can degrade efficiency, radiate noise into the circuit,
and lead to device overvoltage stress. Careful component
layout and printed circuit design minimizes the voltage
spikes in the converter. Consider, as an example, the turn-off
transition of the upper MOSFET. Prior to turn-off, the upper
MOSFET was carrying the full load current. During the turn-
off, current stops flowing in the upper MOSFET and is picked
up by the lower MOSFET or Schottky diode. Any inductance
in the switched current path generates a large voltage spike
during the switching interval. Careful component selection,
tight layout of the critical components, and short, wide circuit
traces minimize the magnitude of voltage spikes.
There are two sets of critical components in a DC-DC
converter using an ISL6523A controller. The switching
power components are the most critical because they switch
large amounts of energy, and as such, they tend to generate
equally large amounts of noise. The critical small signal
components are those connected to sensitive nodes or
those supplying critical bypass current.
The power components and the controller IC should be
placed first. Locate the input capacitors, especially the high-
frequency ceramic de-coupling capacitors, close to the
power switches. Locate the output inductor and output
capacitors between the MOSFETs and the load. Locate the
PWM controller close to the MOSFETs.
The critical small signal components include the bypass
capacitor for VCC and the soft-start capacitor, C
SS
. Locate
these components close to their connecting pins on the
control IC. Minimize any leakage current paths from any SS
node, since the internal current source is only 28
μ
A.
A multi-layer printed circuit board is recommended. Figure 9
shows the connections of the critical components in the
converter. Note that the capacitors C
IN
and C
OUT
each
could represent numerous physical capacitors. Dedicate one
solid layer for a ground plane and make all critical
component ground connections with vias to this layer.
Dedicate another solid layer as a power plane and break this
plane into smaller islands of common voltage levels. The
power plane should support the input power and output
power nodes. Use copper filled polygons on the top and
bottom circuit layers for the PHASE nodes, but do not
unnecessarily oversize these particular islands. Since the
PHASE nodes are subjected to very high dV/dt voltages, the
stray capacitor formed between these islands and the
surrounding circuitry will tend to couple switching noise. Use
the remaining printed circuit layers for small signal wiring.
The wiring traces from the control IC to the MOSFET gate
and source should be sized to carry 2A peak currents.
PWM1 Controller Feedback Compensation
Both PWM controllers use voltage-mode control for output
regulation. This section highlights the design consideration
for a voltage-mode controller requiring external
compensation. Apply these methods and considerations
only to the synchronous PWM controller. The considerations
for the standard PWM controller are presented separately.
Figure 10 highlights the voltage-mode control loop for a
synchronous-rectified buck converter. The output voltage
(V
OUT
) is regulated to the Reference voltage level. The
reference voltage level is the DAC output voltage (DACOUT)
for PWM1. The error amplifier output (V
E/A
) is compared with
the oscillator (OSC) triangular wave to provide a pulse-width
modulated wave with an amplitude of V
IN
at the PHASE node.
The PWM wave is smoothed by the output filter (L
O
and C
O
)..
The modulator transfer function is the small-signal transfer
function of V
OUT
/V
E/A
. This function is dominated by a DC
Gain, given by V
IN
/V
OSC
, and shaped by the output filter, with
a double pole break frequency at F
LC
and a zero at F
ESR
.
FIGURE 9. PRINTED CIRCUIT BOARD POWER PLANES AND
ISLANDS
V
OUT1
Q1
L
OUT1
Q2
Q3
Q4
C
SS24,13
+12V
C
VCC
VCC
OCSET2
VIA/THROUGH-HOLE CONNECTION TO GROUND PLANE
ISLAND ON POWER PLANE LAYER
ISLAND ON CIRCUIT PLANE LAYER
C
OUT1
CR1
ISL6523A
C
IN
C
OUT2
V
OUT2
V
OUT3
+5V
IN
SS24
SS13
PGND
LGATE1
UGATE1
PHASE1
DRIVE3
PHASE2
KEY
L
OUT2
GND
UGATE2
OCSET1
R
OCSET1
R
OCSET2
C
OCSET1
C
OCSET2
L
V
OUT4
DRIVE4
+3.3V
IN
L
IN
CR2
Q5
C
OUT3
C
OUT4
L
L
L
ISL6523A
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| ISL6523ACB | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| ISL6523CB | 功能描述:IC CTRLR VRM8.5 PWM DUAL 28-SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,000 系列:- 應(yīng)用:電源，ICERA E400，E450 輸入電壓:4.1 V ~ 5.5 V 輸出數(shù):10 輸出電壓:可編程 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:42-WFBGA，WLCSP 供應(yīng)商設(shè)備封裝:42-WLP 包裝:帶卷 (TR) |
| ISL6523CB-T | 功能描述:IC CTRLR VRM8.5 PWM DUAL 28-SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,000 系列:- 應(yīng)用:電源，ICERA E400，E450 輸入電壓:4.1 V ~ 5.5 V 輸出數(shù):10 輸出電壓:可編程 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:42-WFBGA，WLCSP 供應(yīng)商設(shè)備封裝:42-WLP 包裝:帶卷 (TR) |
| ISL6523CBZ | 功能描述:IC CTRLR VRM8.5 PWM DUAL 28-SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標(biāo)準(zhǔn)包裝:43 系列:- 應(yīng)用:控制器，Intel VR11 輸入電壓:5 V ~ 12 V 輸出數(shù):1 輸出電壓:0.5 V ~ 1.6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:48-VFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:48-QFN（7x7） 包裝:管件 |
| ISL6523CBZ-T | 功能描述:IC CTRLR VRM8.5 PWM DUAL 28-SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標(biāo)準(zhǔn)包裝:43 系列:- 應(yīng)用:控制器，Intel VR11 輸入電壓:5 V ~ 12 V 輸出數(shù):1 輸出電壓:0.5 V ~ 1.6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:48-VFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:48-QFN（7x7） 包裝:管件 |
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