OMO ElectronicOMO Electronic
Expand menu
Hello, Sign inMy Account
0 Cart

EL7556DCMZ

P1-P3P4-P6P7-P9P10-P11
7
Typical Performance Curves
2.3
1.9
1.7
1.3
1.1
0.9
0.7
V
OUT
(V)
2.1
1.5
3.0
0
20
V
DD
(V)
I
Q
(mA)
3.5 4.5 5.0
Power On Reset
40
2.5
30
10
4.0
Minimum Output Voltage vs F
OSC
F
OSC
(kHz)
V
DD
=5.5V
V
DD
=4.5V
V
DD
=5V
T
J
=120°C
41
35
29
27
25
Θ
JA
(°C/W)
Bare Cu Area (in
2
)
39
31
37
33
Θ
JA
vs Cu Area
6.004.002.001.00 5.00
8.0
7.0
5.5
5.0
4.5
4.0
I
LOAD
(A)
T
A
(°C)
6.0
7.5
6.5
Maximum I
LOAD
vs Temperature
7556 Demo Board (31°C/W)
38
32
30
24
20
R
DSON
(mΩ)
Temperature (°C)
36
26
34
28
R
DSON
vs Temperature
125755025 100
0.00 3.00
22
0
Board with no
Components
Board with
Inductor
100 LFPM
Still Air
OUTEN connected to OT
70604030 65
25 50
4535
55
T
A
=25°C
OUTEN=V
DD
F
OSC
=500k
EL7556D
8
Pin Descriptions
I = Input, O = Output, S = Supply
PIN
NUMBER PIN NAME PIN TYPE FUNCTION
1 FB1 I Voltage feedback pin for the buck regulator. Active when VCC2DET is logic low. Normally connected to
external resistor divider between V
OUT
and GND. A 2µA pull-up current forces V
OUT
to V
SS
in the event
that FB1 is floating and VCC2DET is inadvertently connected to GND.
2 CREF I Bandgap reference bypass capacitor. Typically 0.1µF to V
SS
.
3 CSLOPE I Slope compensation capacitor. Ramp width corresponds to LX duty cycle. C
SLOPE
to C
OSC
ratio is
normally 1:1.5.
4 COSC I Oscillator timing capacitor. F
OSC
(Hz) can be approximated by: F
OSC
(Hz) = 0.0001/C
OSC
. C
OSC
in
Farads.
5 VDD S Power Supply for PWM control circuitry. Normally the same potential as V
IN
.
6 VIN S Power supply for the buck regulator. Connected to the drain of the high-side NMOS FET.
7 VSSP S Ground return for the buck regulator. Connected to the source of the low-side synchronous NMOS FET.
8 VIN S Same as pin 6.
9 VSSP S Same as pin 7.
10 VSSP S Same as pin 7.
11 VSSP S Same as pin 7.
12 VSSP S Same as pin 7.
13 VCC2DET I VCC2DET interface logic input. When driven to logic 1 V
OUT
= 3.500V. When driven to logic 0 the PWM
uses FB1 to determine V
OUT
: V
OUT
= 1.0V*(1+R3/R4).
14 OUTEN I The switching regulator output is enabled when logic 1. The reference voltage output operates whenever
the power supply is qualified (V
DD
>VPOR) regardless of the state of this pin.
15 OT O Over temperature indicator. Normally high. Pulls low when die temperature exceeds 135°C, returns to
the high state when die temperature has cooled to 100°C.
16 PWRGD O Power good window comparator output. Logic 1 when regulator output is within ±10% of programmed
voltage.
17 TEST I Test pin. Must be connected to VSSP in normal operation.
18 VSSP S Same as pin 7.
19 VSSP S Same as pin 7.
20 LX O Inductor drive pin. High current switching output whose average voltage equals the regulator output
voltage.
21 LX O Same as pin 20.
22 LX O Same as pin 20.
23 LX O Same as pin 20.
24 VHI I Gate drive to high-side driver. Bootstrapped from LX with a 0.1µF capacitor.
25 VSS S Ground return for the control circuitry.
26 C2V I Connected to voltage doubler output. Supplies gate drive to the low-side driver.
27 CP O Drives the negative side of charge pump capacitor at one-half the oscillator frequency F
OSC
.
28 FB2 I Voltage feedback pin. Active when VCC2DET is logic 1. Internally preset to V
OUT
= 3.5V.
EL7556D
9
Block Diagram
Applications Information
Circuit Description
General
The EL7556D is a fixed frequency, current mode controlled
DC:DC converter with integrated N-channel power
MOSFETS and a high precision reference. The device
incorporates all of the active circuitry required to implement a
cost effective, user-programmable 6A synchronous buck
converter suitable for use in CPU power supplies. By
combining fused-lead packaging technology with an efficient
synchronous switching architecture, high power outputs
(21W) can be realized without the use of discrete external
heat sinks.
Theory of Operation
The EL7556D is composed of 7 major blocks:
1. PWM Controller
2. Output Voltage Mode Select
3. NMOS Power FETS and Drive Circuitry
4. Bandgap Reference
5. Oscillator
6. Temperature Sensor
7. Power Good and Power On Reset
PWM Controller
The EL7556D regulates output voltage through the use of
current-mode controlled pulse width modulation. The three
main elements in a PWM controller are the feedback loop
and reference, a pulse width modulator whose duty cycle is
controlled by the feedback error signal, and a filter which
averages the logic level modulator output. In a step-down
(buck) converter, the feedback loop forces the time-
averaged output of the modulator to equal the desired output
voltage. Unlike pure voltage-mode control systems current-
mode control utilizes dual feedback loops to provide both
output voltage and inductor current information to the
controller. The voltage loop minimizes DC and transient
errors in the output voltage by adjusting the PWM duty-cycle
in response to changes in line or load conditions. Since the
output voltage is equal to the time-average of the modulator
output the relatively large LC time constants found in power
supply applications generally results in low bandwidth and
poor transient response. By directly monitoring changes in
inductor current via a series sense resistor the controller’s
response time is not entirely limited by the output LC filter
and can react more quickly to changes in line or load
conditions. This feed-forward characteristic also simplifies
AC loop compensation since it adds a zero to the overall
loop response. Through proper selection of the current-
feedback to voltage-feedback ratio, the overall loop
response will approach a one pole system. The resulting
system offers several advantages over traditional voltage
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
S
-
+
FB1, Pin 1
FB2, Pin 28
VCCDET, Pin 13
CSLOPE, Pin 3
CREF, Pin 27
2-1 MUX
1.26V
4V
UVLO
V2X
R
SS
PWM
Current Limit
COSC, Pin 4
VDD
VDD
C
SS
Zero Cross Detect
Current Sense
LEB T
DELAY
Over Temp
Sensor
Q
Q
R
S
FF
R
S
PWRGD, Pin 16
CP, Pin 27
C2V, Pin 26
VHI, Pin 24
VDD and VIN,
Pin 5,6,8
LX, Pin 20-23
VSSP, Pin 9-
12, 18-19
OT, Pin 15
V
SS,
Pin 25
S
R
OUTEN, Pin 14
EL7556D
P1-P3P4-P6P7-P9P10-P11

EL7556DCMZ

Mfr. #:
Buy EL7556DCMZ
Manufacturer:
Renesas / Intersil
Description:
IC REG BUCK ADJUSTABLE 6A 28SOIC
Lifecycle:
New from this manufacturer.
Delivery:
DHL FedEx Ups TNT EMS
Payment:
T/T Paypal Visa MoneyGram Western Union

Products related to this Datasheet