APW7095 查看數據表（PDF） - Anpec Electronics

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APW7095

6-Channel DC/DC Converter Control IC

Anpec Electronics 

APW7095/A

Application Information

Soft-Start Interval Settings

The CH6 soft-start time depends on the capacitor CCIN6

and is determined as the following equation:

ts

(S)

=

-

C CIN6

(F)

⋅

37.5

100

(k Ω)

(kΩ)

⋅

62.5

(kΩ)

⋅ ln1−

VCIN6 (V)

1.26 (V)



V CIN6

CIN6

VB(2V)

37.5k

Error

Amp. 6

CCIN6

62.5k

(2) CH4

Vo (V) = - 1.25V ⋅ R1

R2

VO

R1

INA4

R2

OUTA4

R3

I N4

1.2 5V

INV

Amp. 4

Error

Amp. 4

The soft-start time until CH6 output voltage reaches 95%

of the set voltage is determined as the following equation:

ts (S) ≈ 0.07 ⋅ CCIN6 ( µF)

On CH1 to CH5, the soft-start time depending on the

capacitor CS determined as the following equation :

ts (S) ≈ 1.25 ⋅ CS ( µF)

Triangular Oscillator Frequency Setting

The triangular oscillator frequency set by the timing ca-

pacitor (CT) connected to the CT pin and the timing resis-

tor (RT) connected to the RT pin determined as the fol-

lowing equation:

fOSC (kHz)

≈

RT

900000

(k Ω ) ⋅ CT

(pF)

Output Voltage Settings

The output voltage is set by the external resistor-divider

connected with converter output, error amplifier input, and

ground.

(1) CH1 to CH3, CH5

Vo

(V)

=

1.25V

⋅

1+



R1

R2





VO

R1

IN1

Error

Amp. 1

R2

1.25 V

(3) CH6

Vo

(V)

=

1.26V

⋅

1+



R1

R2





VO

R1

IN6

R2

CIN6

VB(2V)

37.5k

62.5k

Error

Amp. 6

Time Constant Setting for Timer-Latch Short-Circuit

Protection Circuit

The time constant for timer-latch short-circuit protection

is set by the capacitor CSCP and determined as the fol-

lowing equation :

tPE (S) = 0.70 ⋅ CSCP ( µF)

Dead-Time Setting

The dead-time control pin (DTC) is designed to set the

maximum ON duty of the main-side MOSFET. When the

device is set for step-up inverted output based on the

step-up or step-up/down Zeta method or flyback method,

the FB pin voltage may reach and exceed the triangular

wave voltage due to load fluctuation. If this is the case, the

output MOSFET is fixed to a ON duty of 100 %. To prevent

this, set the maximum duty of the output MOSFET. Con-

necting a resistor- divider between VREF, DTC and GND

pins provides a voltage VDTC to DTC pin. When the the

voltage at the DTC pin is higher than the triangular wave

voltage (CT1/2), the output transistor is turned on. The

maximum duty is calculated as the following equation:

Copyright © ANPEC Electronics Corp.

17

Rev. A.4 - Dec., 2008

www.anpec.com.tw

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