MP6005

– WIDE-INPUT, HIGH-EFFICIENCY FLYBACK AND FORWARD CONTROLLER

MP6005 Rev. 1.0

www.MonolithicPower.com

15

2/5/2021

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© 2021 MPS. All Rights Reserved.

OPERATION

Start-Up and Power Supply

The MP6005 features an 80V internal start-up

circuit. When the input voltage (VIN) exceeds

5.5V, the VCC

pin’s capacitor is charged by the

internal LDO regulator (LDO). Typically, if VIN

exceeds 10V, the

VCC’s pin voltage (VCC) is

regulated at 8.5V and VCC under-voltage

lockout (UVLO) is 5.7V. Aside from VCC UVLO,

the MP6005 also has EN UVLO (typically 2V).

When VCC exceeds the 5.7V UVLO threshold

and the EN pin is pulled high, the part begins

operating.

After the MP6005 turns on, the VCC pin can be

powered by the auxiliary winding transformer to

reduce IC power loss. The auxiliary power must

be greater than VCC regulation (8.5V) to

override the internal LDO. The internal reverse-

blocking circuit allows VCC to exceed VIN if VCC

has bias power. VCC should be below 16V due

to the pin

’s voltage rating.

If VIN is below 8.5V and VCC is not regulated at

8.5V, the internal high-voltage VCC LDO has a

voltage drop of about 1.5V. This allows the

MP6005 to work when VIN is as low as 8V.

Enable (EN) Control

The EN pin is the on/off control for the MP6005.

When

the EN pin’s voltage (VEN) exceeds 1V,

the MP6005

’s micro-power mode allows the

device to turn on some of the internal circuits. If

VEN exceeds the turn-on threshold (2V), all

functions are turned on and the GATE/SYNC

driver signal starts up. The GATE/SYNC signal

can be disabled if VEN drops to about 1.8V.

Micro-power mode is only disabled after VEN

drops below 0.4V. After shutdown, the MP6005

sinks a current below 1µA from the input power

supply.

EN can program the VIN

pin’s start-up voltage

through

a

resistor

divider.

The

maximum

recommended voltage for EN is 6.5V. If

EN’s

divider

voltage

exceeds

6.5V,

it

is

recommended to use a divider resistor to limit

the current going into EN. One internal Zener

diode on EN clamps VEN when the divider

voltage exceeds 6.5V. Ensure the clamped

Zener diode current into EN is below 0.4mA

with an external pull-up resistor.

Work Mode Detection

After turning on, the MP6005 produces a 40µA

output current to the MODE pin to detect the

resistor setting. If the MODE pin

’s voltage

(VMODE) exceeds 2.2V, the MP6005 works in

primary-side regulation (PSR) mode, and the

internal error amplifier (EA) turns on. If MODE

is connected to GND through a resistor.

the MP6005 works in secondary-side regulation

(SSR) mode and the internal EA turns off while

COMP is pulled up to the internal 5V power

source through a 10k

Ω resistor. Table 1 shows

MODE program options.

Table 1: MODE Program Options

MODE to GND

Resistance

(kΩ)

Work

Mode

Dead Time

(ns)

Min

Typ

(1%)

Max

0

0

3.3

SSR

100

7.32

7.5

8.2

SSR

150

16

16.9

18.7

SSR

200

32.4

32.4

33

SSR

300

64.9

Float

Float

PSR

150

In PSR

mode, the output voltage (VOUT)

feedback signal is detected by auxiliary winding

from the FB pin. Under light-load conditions, the

MP6005 reduces the frequency accordingly.

Under

no-load

conditions,

the

frequency

remains above 30kHz. In SSR mode, the VOUT

feedback signal is detected by the COMP pin,

and the MP6005 maintains a fixed frequency.

The peak current is regulated by the COMP

pin’s voltage (VCOMP) until the MP6005’s power-

save mode (PSM) is triggered.

Once the MP6005 turns on, there is a 500µs

period before the device starts switching. The

MODE

pin,

dead

time,

dither,

and

VOUT

compensation are detected during this period.

The MODE pin determines the PSR and SSR

modes. It also programs the dead time between

the GATE and SYNC pins. Table 1 shows the

programming options.

The MODE detection current lasts about 200µs.

Typically, a resistor from MODE to GND is

sufficient. A capacitor from MODE to GND may

be required for filtering in a noisy environment.

This capacitor must be below 100pF to allow