MAX5003EEE-T Maxim Integrated Products, MAX5003EEE-T Datasheet - Page 7

• Manufacturer Part Number: MAX5003EEE-T
• Description: Voltage Mode PWM Controllers PWM Power-Supply Controller
• Manufacturer: Maxim Integrated Products

Specifications of MAX5003EEE-T

• Topology: Flyback, Forward
• Output Current: 1000 mA
• Switching Frequency: 300 KHz
• Duty Cycle (max): 75 %
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Package / Case: QSOP-16
• Mounting Style: SMD/SMT
• Synchronous Pin: Yes

The MAX5003 is a PWM controller designed for use as
the control and regulation core of voltage-mode control
flyback converters or forward-voltage power convert-
ers. It provides the power-supply designer with maxi-
mum flexibility and ease of use. The device is specified
up to 110V and will operate from as low as 11V. Its
maximum operating frequency of 300kHz permits the
use of miniature magnetic components to minimize
board space. The range, polarity, and range of output
voltages and power are limited only by design and by
the external components used.
This device works in isolated and nonisolated configu-
rations, and in applications with single or multiple out-
put voltages. All the building blocks of a PWM
voltage-mode controller are present in the MAX5003
and its settings are adjustable. The functional diagram
is shown on Figure 1.
The MAX5003 offers a voltage-mode control topology
and adds features such as fast input voltage feed for-
ward, programmable maximum duty cycle, and high
operating frequencies. It has all the advantages of cur-
rent-mode control—good control loop bandwidth,
same-cycle response to input voltage changes, and
pulse-by-pulse current limiting. It eliminates disadvan-
tages such as the need for ramp compensation, noise
sensitivity, and the analytical and design difficulties of
dealing with two nested feedback loops. In summary,
voltage-mode control has inherent superior noise
immunity and uses simpler compensation schemes.
PIN
11
12
13
14
15
16
NAME
AGND
PGND
NDRV
Modern Voltage-Mode Controllers
V
V
CS
CC
DD
_______________________________________________________________________________________
Detailed Description
Analog Ground. Connect to PGND close to the IC.
Current Sense with Blanking. Turns power switch off if V
Connect a 100Ω resistor between CS and the current-sense resistor (Figure 2). Connect CS to PGND if
not used.
Power Ground. Connect to AGND.
Gate Drive for External N-Channel Power FET
Output Driver Power-Rail Decoupling Point. Connect a capacitor to PGND with half the value used for
V
FREQ pins from this pin.
9.75V Internal Linear-Regulator Output. Drive V
supply. V
DD
bypass very close to the pin. If synchronizing several controllers, power the fan-out buffer driving the
DD
is also the supply voltage rail for the chip. Bypass to AGND with a 5µF to 10µF capacitor.
Power-Supply Controller
The MAX5003’s power stages operate over a wide
range of supply voltages while maintaining low power
consumption. For the high end of the range (+36V to
+110V), power is fed to the V+ pin into a depletion
junction FET preregulator. This input must be decou-
pled with a 0.1µF capacitor to the power ground pin
(PGND). To decouple the power line, other large-value
capacitors must be placed next to the power trans-
former connection.
The preregulator drops the input voltage to a level low
enough to feed a first low-dropout regulator (LDO)
(Figure 1). The input to the LDO is brought out at the ES
pin. ES must also be decoupled with a 0.1µF capacitor.
In applications where the maximum input voltage is
below 36V, connect ES and V+ together and decouple
with a 0.1µF capacitor.
The first LDO generates the power for the V
V
bypass to AGND must be a 5µF to 10µF capacitor.
When the maximum input voltage is always below
18.75V, power may also be supplied at V
case, connect V+, ES, and V
Forcing voltages at V
Characteristics) disables the first LDO, typically reduc-
ing current consumption below 50µA (see Typical
Operating Characteristics).
Following the V
V
cuitry, and external power MOSFET driver. This regula-
tor is needed because the V
too high for the external N-channel MOSFET gate. The
DD
CC
FUNCTION
DD
: the power bus for the internal logic, analog cir-
line is available at the V
to a voltage higher than 10.75V to bootstrap the chip
High-Voltage PWM
CS
Pin Description (continued)
rises above 100mV (referenced to PGND).
DD
LDO is another regulator that drives
Internal Power Regulators
DD
above 10.75V (see Electrical
DD
DD
DD
pin for decoupling. The
together.
voltage level would be
DD
DD
line. The
; in this
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